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150 mm Indium Phosphide wafers are now commercially available with crystal quality comparable to wafer of smaller radius. This may pave the way for scaling up the production of a multitude of photonic devices for Datacoms operating in the 1.30- 1. 55 μ m infrared range with a gain in wafer surface of factor 4 and a reduction of roughly 50% in die cost. To achieve this goal, it is of utmost importance to prove that both AlGaInAs and InGaAsP quaternary compound semiconductors can be grown by metal–organic chemical vapor deposition (MOCVD) on wafers of larger sizes with both thickness and composition uniformities comparable to those achievable on 75 mm. In this article, we report pioneering production technology developments based on the Planetary Reactor® design. Both reactor and related inlet geometry have been deeply revisited with the introduction of a novel 4-fold injector, which in combination with Cl 2 In-situ chamber clean, prove to enable such transition in wafer size. Sub-nanometric photoluminescence in-wafer uniformities are demonstrated and historic challenges, such as drift in material composition of highly sensitive InGaAsP alloys during a production campaign, are addressed thanks to this unique combination. Uniformity, tunability and reproducibility results are thus presented for two prototypical case scenarios: a highly strained AlGaInAs multiple quantum well (MQW) and a bulk InGaAsP layer with wavelength emission of 1550 nm and 1100 nm respectively to corroborate reactor flexibility in meeting industry requirements for next device generation. [Display omitted] • MOCVD growth of IIIAsP compound semiconductors on 150 mm Indium Phosphide wafer. • IIIAsP material uniformity tuning by 4-fold gas inlet system. • Cl 2 based in-situ chamber clean for superior system repeatability. [ABSTRACT FROM AUTHOR]

Highlights • n-Cladding layer materials of II-VI devices on InP substrates were investigated. • J-V characteristics of MgZnCdSe and MgSe/ZnCdSe SL n-clad materials were evaluated. • Resistivity of MgZnCdSe was lower than that of the MgSe/ZnCdSe SL. • Schottky characteristics were observed for both MgZnCdSe and MgSe/ZnCdSe SL samples. • ZnCdSe/MgZnCdSe graded SLs was proposed to reduce the Schottky characteristics. Abstract MgSe/ZnCdSe superlattices (SLs) and n-MgZnCdSe quaternaries were investigated as an n-cladding layer material of II-VI compound semiconductor optical devices on InP substrates. n-type samples consisting of n-doped ZnCdSe and n-MgSe/ZnCdSe SL or n-MgZnCdSe layers were fabricated on n-InP substrates by molecular beam epitaxy. From the injection current density versus applied voltage (J-V) characteristics of the samples, it was found that the applied voltage and resistivity of the MgZnCdSe sample were lower than those of the SL sample. This shows that MgZnCdSe is more suitable for the n-cladding layer. On the other hand, Schottky characteristics were observed for both samples, which were ascribed to conduction band hetero-barriers between the n-ZnCdSe and the SL or MgZnCdSe layers. The Schottky characteristics cause high applied voltages of the II-VI optical devices. To solve this problem (i.e., the Schottky characteristics), the incorporation of ZnCdSe/MgZnCdSe graded SLs at the interface between the n-ZnCdSe and MgZnCdSe layers was proposed. From the J-V characteristics, it was confirmed that the Schottky characteristics and applied voltages were reduced by introducing the graded SLs. This shows that the graded SLs are effective for lowering the applied voltages of II-VI optical devices on InP substrates. [ABSTRACT FROM AUTHOR]

Highlights • InAs/In 0.83 Al 0.17 As quantum wells have been grown on GaP and InP substrates. • Room temperature photoluminescence up to 2.8 µm has been observed. • The structures grown on GaP and InP have the similar lattice quality. • The samples on GaP and InP do not show prominent Raman shift difference. Abstract Type-I InAs quantum wells have been grown on metamorphic In 0.83 Al 0.17 As buffers on (0 0 1)-oriented GaP and InP substrates by gas source molecular beam epitaxy. The structural and optical properties as well as strain conditions were characterized and investigated to compare the material quality of samples grown on GaP and InP substrates, respectively. Photoluminescence up to 2.8 μm has been observed for the quantum wells at room temperature. The quantum wells on GaP and InP show the similar photoluminescence intensity, X-ray diffraction peaks and Raman shift performances. These results indicate the potential to demonstrate type-I mid-infrared light sources on Si substrate using GaP as a template. [ABSTRACT FROM AUTHOR]

Highlights • We have fabricated InP/GaInAs core-multishell nanowires using the indium catalyst. • By increasing the shell-periods, we observed a star-shaped cross section. • The number of PL peaks was found to increase with increasing number of periods. • PL peak wavelength was red-shifted as the number of periods increased. Abstract We successfully fabricated core-multishell nanowires using low-pressure metal organic vapor phase epitaxy (MOVPE) in self-catalytic vapor-liquid-solid (VLS) mode. The central core consists of an InP nanowire, and the shells are composed of alternating InP and GaInAs layers. The dependence of the shape and optical characteristics of the nanowires on the number of InP/GaInAs periods were investigated. By increasing the shell-periods, we observed a star-shaped cross section. The optical characteristics of the nanowires were investigated by room-temperature photoluminescence (PL) spectroscopy. The number of PL peaks was found to increase with increasing number of periods, and the peaks became redshifted. [ABSTRACT FROM AUTHOR]

Highlights • We have demonstrated SCH-MQW FP LD on wafer bonded InP/Si substrate using MOVPE. • We have obtained mirror-like surface without cross-hatch or dislocation after the crystal growth. • We have successfully obtained room temperature lasing with threshold current density of 2.85 kA/cm2 under pulsed current condition. Abstract We have successfully obtained a metalorganic vapor phase epitaxy (MOVPE) grown GaInAsP/GaInAsP separate confinement heterostructure structure multi-quantum well (SCH-MQW) laser diode (LD) on a directly InP/Si substrate. InP/Si substrate was prepared by the hydrophilic bonding of a thin InP film (1 µm) and silicon substrate with annealing at 400 °C. After crystal growth of the SCH-MQW laser structure on the InP/Si substrate, the surface was mirror-like and without any cross hatches or dislocations. Room temperature pulsed current lasing was then achieved using a Fabry-Perot cavity LD with a threshold current density of 2.85 kA/cm2. [ABSTRACT FROM AUTHOR]

• Inexpensive technological process for high-yield production of semi-insulating InP wafers. • The obtained semi-insulating wafers have properties that outperform those of standard Fe-doped InP. • The procedure is simple and reproducible, ready for industrial application. A novel technique for preparation of high-resistivity indium phosphide (InP) via post-growth treatment of undoped n-type wafers is presented. The method includes the deposition of a controlled quantity of iron on both faces of as-cut wafers by a simple chemical bath, and the subsequent Fe diffusion by thermal annealing. The reproducible low - to – high resistivity conversion is explained considering two simultaneous phenomena: the annealing-controlled in-diffusion of Fe deep acceptors and the out-diffusion of hydrogen-related shallow donors. Differently from standard Fe-doped melt-grown InP single crystals, this process does not suffer from segregation, thus the Fe-concentration is constant from wafer to wafer, with no striations and radial gradients deriving from the convex solid–liquid interface during growth. Main advantages of the developed process are: i) an entire undoped InP boule may be sliced and converted to semi-insulating, which makes the process cost-effective; ii) reproducible and uniform semi-insulating properties from batch to batch of wafers; iii) the Fe incorporation is precisely controlled, and minimized, so that electrical characteristics of Fe-diffused wafers are superior to those of traditional semi-insulating melt-grown InP crystals doped via addition of elemental Fe to the melt. [ABSTRACT FROM AUTHOR]

In this work, we have investigated the growth of highly n-doped gallium arsenide (GaAs) and gallium indium phosphide (GaInP) with tellurium (Te) by metal organic vapor phase epitaxy (MOVPE) using diisopropyl telluride (DIPTe), aiming at fabricating high performances tunnel junctions. A parametric study is performed in order to optimize the n ++ -type doping. Concentrations above 2.7 × 10 19  cm −3 were achieved in both GaAs and GaInP layers. Using these Te-doped layers, we fabricated both n on p (n/p) and p on n (p/n) tunnel junctions. The p/n tunnel junction required additional annealing steps during growth, due to memory effect and surfactant properties of Te. We characterized GaAs/GaAs, GaAs/AlGaAs and AlGaAs/GaInP tunnel junctions with peak tunneling current densities as high as 250, 3000 and 1500 A/cm 2 respectively. These tunnel junction performances are suitable for multijunction solar cells operating under high concentration. [ABSTRACT FROM AUTHOR]

We investigate growth conditions for strain-compensated In0.67Ga0.33As/In0.36Al0.64As/InP quantum cascade lasers (QCLs) by solid-source molecular beam epitaxy (SSMBE). The extensive discussion of growth procedures is presented. The technology was first elaborated for In0.53Ga0.47As/In0.52Al0.48As material system lattice matched to InP. After that QCLs with lattice matched active region were grown for validation of design and obtained material quality. The next step was elaboration of growth process and especially growth preparation procedures for strain compensated active regions. The grown structures were examined by HRXRD, AFM, and TEM techniques. The on-line implementation of obtained results in subsequent growth runs was crucial for achieving room temperature operating 4.4-μm lasers. For uncoated devices with Fabry-Perrot resonator up to 250 mW of optical power per facet at 300 K was obtained under pulsed conditions. The paper focuses on MBE technology and presents developed algorithm for strain-compensated QCL growth. [ABSTRACT FROM AUTHOR]

• VCSEL Wafer diameters on GaAs were initially developed at 100 mm and rapidly expanded to 150 mm. • Improved uniformity in reflectivity, thickness and composition. • 150 mm VCSELs on GaAs were qualified from a newly constructed state-of-the-art epi -foundry. • New substrate material was considered – Ge demonstrated significantly reduced wafer bow, zero EPD substrate with minimal slip. • Growth of VCSELs on 200 mm wafers. III-V Compound Semiconductors (CS) such as Gallium Arsenide (GaAs), Indium Phosphide (InP) and more latterly, Gallium Nitride (GaN) are critical Key Enabling Technologies, fundamentally underpinning several recent major technology revolutions. Two major current and likely-future markets within the burgeoning photonics industry ($7 billion) are 3D imaging and sensing and LIDAR applications, with high predicted market growth. Datacom and industrial markets add considerable further momentum to this market growth. Evidence of such expansion is provided in the manufacturing of VCSEL-based devices, which have in recent years, entered a rapid growth phase. For the mass-manufacturing of for example, GaAs/AlGaAs-based VCSEL MOVPE epitaxy, many areas require addressing in key underlying R&D, such as cost-reduction and in thickness and wavelength uniformity. In addition, scalability, (e.g. to 150 mm wafers), automation and in-situ process control will impact yield and throughput improvements. We will demonstrate the preparations for mass-manufacturing, through improvements implemented across the evolution of the VCSEL epiwafers from smaller diameters, through 100 mm and on to 150 mm wafers. More recently however, further developments have led to even larger diameter VCSEL wafer epitaxy, on both GaAs and Ge 200 mm substrates. Challenges in growing on such large diameter wafers will be presented from the epitaxy (layer uniformity and wafer bow) and device fabrication perspective. We will demonstrate how these improvements impact on the manufacturing readiness of production VCSEL wafers. [ABSTRACT FROM AUTHOR]

• The complex single heater is designed and developed or VGF process. • The control system of VGF process is simplified and now production cost can be decreased. • Full process transient optimization method is proposed and developed. A complex single heater is designed for a VGF process to decrease process complexity caused by the use of a multi-heater system. To do this, a set of design criteria is selected to ensure that the final quality of the crystal is acceptable. Then a 3D transient finite element model is coupled with a new optimization procedure. All important physical phenome a such as temperature distribution, turbulent melt flow, thermal stress and crystal front shape are monitored and controlled during crystal growth. Using these, a single heater is designed for 4″ InP VGF crystal growth which meets all design criteria. It is concluded that using the complex single heater, high quality InP crystal growth by VGF process is possible. [ABSTRACT FROM AUTHOR]

The nucleation and the structural and optical properties of InP nanowires (NWs) grown on Si(111) by molecular beam epitaxy using the vapor-liquid-solid method with gold-indium droplets as catalyst are investigated as a function of the temperature of the formation of the catalyst droplets and of the NW growth time. It is highlighted a complex behavior of the gold-indium catalyst droplets depending on the temperature. It is then shown than an InP pyramid-like pedestal is formed prior to the NW growth. When the temperature of formation of the catalyst droplets is lower than 550 °C, almost only vertically standing pure wurtzite InP NWs are grown on Si(111). [ABSTRACT FROM AUTHOR]

The catalyst-free metal organic vapor phase epitaxial growth of InP nanowires on silicon (001) substrate is investigated using selectively grown GaAs buffer layers in V-shaped trenches. A yield up to 70% of nanowires is self-aligned in uncommon 〈112〉 directions under the optimized growth conditions. The evolution mechanism of self-aligned 〈112〉 directions for nanowires is discussed and demonstrated. Using this growth method, we can achieve branched and direction switched InP nanowires by varying the V/III ratio in situ. The structure of the nanowires is characterized by scanning electron microscope and transmission electron microscopy measurements. The crystal structure of the InP nanowires is stacking-faults-free wurtzite with its c axis perpendicular to the nanowire axis. [ABSTRACT FROM AUTHOR]

Sb-based metamorphic DBR membranes are developed for InP-based vertical cavity laser applications. The reflectivity of the metamorphic DBR membrane is compared to the reflectivity of a lattice-matched DBR to characterize the optical quality of the DBR membrane. The metamorphic interface between InP and the III-antimonides is found to degrade the reflectivity of the DBR. Therefore, the growth temperature for the metamorphic DBR is optimized in order to obtain highly reflective (>99.8%) III-Sb thin-film membranes. [ABSTRACT FROM AUTHOR]

We investigate the molecular beam epitaxial growth of GaAsBi and GaInAsBi layers on GaAs and InP-substrates as the materials are intended to serve as an active region in optoelectronic devices. The layers were grown at substrate temperatures between 250–400 °C and for all layers the growth rate was kept at a value of 1 ML/s. We show that bismuth incorporation into Ga(In)As is independent of the applied arsenic (As 4 ) overpressure and can be allocated to different growth domains depending solely on the parameters bismuth flux and substrate temperature, respectively. The maximum bismuth content that could be incorporated was as high as 20.0% in GaAs. [ABSTRACT FROM AUTHOR]

This work deals with the development of growth processes by droplet epitaxy to obtain InAs quantum dots directly on InP (001) surfaces (without any InGaAs or InAlAs intermediate layer). The indium atoms for droplet formation were deposited at different substrate temperatures, T S , below 300 °C in a solid source molecular beam epitaxy system. From the evolution of the size and shape of the nanostructures with T S , values of magnitudes related with indium atoms diffusivity have been extracted. The photoluminescence signal is investigated for ensemble and single InAs nanostructures emitting around 1.3–1.5 μm. The emission properties drastically change with thermal annealing processes that improve the crystalline quality. [ABSTRACT FROM AUTHOR]

Reflectance Anisotropy Spectroscopy (RAS) was employed to determine the optimal specific molar flow of Sb needed to grow GaInP with a given order parameter by MOVPE. The RAS signature of GaInP surfaces exposed to different Sb/P molar flow ratios were recorded, and the RAS peak at 3.02 eV provided a feature that was sensitive to the amount of Sb on the surface. The range of Sb/P ratios over which Sb acts as a surfactant was determined using the RA intensity of this peak, and different GaInP layers were grown using different Sb/P ratios. The order parameter of the resulting layers was measured by PL at 20 K. This procedure may be extensible to the calibration of surfactant-mediated growth of other materials exhibiting characteristic RAS signatures. [ABSTRACT FROM AUTHOR]

N-doped p-type ZnTe and ZnSeTe contact layers were investigated to evaluate which is more suitable for use in II–VI compound semiconductor optical devices on InP substrates. Contact resistances ( R c ) between the contact layers and several electrode materials (Pd/Pt/Au, Pd/Au, and Au) were measured by the circular transmission line model (c-TLM) method using p-n diode samples grown on InP substrates by molecular beam epitaxy (MBE). The lowest R c (6.5×10 −5 Ω cm 2 ) was obtained in the case of the ZnTe contact and Pd/Pt/Au electrode combination, which proves that the combination is suitable for obtaining low R c . Yellow light-emitting diode devices with a ZnTe and ZnSeTe p-contact layer were fabricated by MBE to investigate the effect of different contact layers. The devices were characterized under direct current injections at room temperature. Yellow emission at around 600 nm was observed for each device. Higher emission intensity and lower slope resistance were obtained for the device with the ZnTe contact layer and Pd/Pt/Au electrode compared with other devices. These device performances are ascribed to the low R c of the ZnTe contact and Pd/Pt/Au electrode combination. [ABSTRACT FROM AUTHOR]

The effects of well widths and well numbers of InGaAs triangular quantum well lasers in 2.30–2.44 μm range using antimony-free material system on InP substrates are investigated. The triangular quantum well was equivalently formed by using gas source molecular beam epitaxy grown InAs/In 0.53 Ga 0.47 As digital alloy and the pseudomorphic growth was confirmed by the X-ray diffraction measurements. Lasing at 2.30 μm above 330 K under continuous wave operation has been achieved for the laser with four 13 nm quantum wells. By increasing the well width to 19 nm, the continuous wave wavelength has been extended to 2.44 μm at 290 K, whereas the epitaxial quality and laser performances are deteriorated. For those lasers with well width up to 19 nm, the moderate reduction of the quantum well numbers can restrict the strain accumulation and improve the laser performances. Continuous wave lasing at 2.38 μm above 300 K has been achieved. [ABSTRACT FROM AUTHOR]

In a previous work [Flores et al., J. Cryst. Growth 398 (2014) 40] [3] we demonstrated the advantages of using a thin InAlAs spacer layer in the fabrication of buried-heterostructure quantum-cascade lasers (QCLs), as it improves the morphology of the interface between the laser core and the InP:Fe lateral cladding. In this paper we investigate aspects of InAlAs, which are relevant for its role as insulating lateral cladding of the laser sidewalls: carrier traps, electrical resistivity, and functionality as a sole lateral cladding. We find that a thin InAlAs spacer layer not only improves the regrowth interface morphology, but also eliminates interface-related shallow electronic states, thus improving the electrical resistivity of the interface. We further find that bulk InAlAs grown by gas-source molecular-beam epitaxy as well as InP:Fe are semi-insulating at room temperature, with specific resistivities of 3 × 10 7 Ω cm and 2 × 10 8 Ω cm , respectively. Both materials have also a high thermal activation energy for electrical conductivity (0.79 eV and 0.68 eV, respectively). In order to compare the performance of InP:Fe and InAlAs as a lateral cladding, lasers were fabricated from the same QCL wafer with differing stripe insulation materials. The resulting lasers differ mainly by the lateral insulation material: SiO 2 , InP:Fe (with InAlAs spacer), and pure InAlAs. All devices show a similar performance and similar temperature dependence, indicating insulating properties of InAlAs adequate for application in lateral regrowth of buried-heterostructure QCLs. [ABSTRACT FROM AUTHOR]

We report on the selective area growth (SAG) of high quality InP layers on patterned (0 0 1)Si substrates at various growth temperatures by metal organic chemical vapor deposition. Thin InP and GaP layers were used as intermediate buffer layers between patterned Si surface and high temperature (HT) InP layer. The growth temperatures of HT InP layers on patterned substrate had strong effect on their growth behaviors including surface morphology. The SAG InP layers grown at 650 °C and 550 °C exhibited the typical {1 1 1} facets and the smooth (0 0 1) top surface, respectively. Anti-phase domain boundaries and defects were trapped by lateral sidewalls of the etched Si substrate. Through the defect necking effect within the etched Si surface, defect-free InP layers with atomically smooth surface were obtained at a growth temperature of 550 °C. [ABSTRACT FROM AUTHOR]

Selective area etching and growth in the metalorganic vapor phase epitaxy (MOVPE) reactor on nano-scale structures have been examined. Using different mask orientations, crystallographic dependent etching of InP can be observed when carbon tetrabromide (CBr 4 ) is used as an etchant. Scanning Electron Microscopy (SEM) investigation of etch profiles showed formation of a U-shaped groove along the [01̄1̄] direction, terminated by {111}B planes with an ~15 nm {100} plateau and transitional {311}B planes, developed in a self-limiting manner. In the perpendicular direction [01̄1] etching with a dominant lateral component driven by fast etched {111}A and {311}A side planes was observed. A directly grown single InGaAs QW in the etched grooves demonstrated different QW profiles: a crescent-shaped on {311}B and {100} planes (along the [01̄1̄] direction) and two separated quarter-circle curvatures grown preferably on {311}A along [01̄1̄]. Room temperature micro-photoluminescence measurements indicated a wavelength red-shift in over 125 nm along [01̄1̄] comparing to [01̄1], which is related to both growth enhancement and composition variation of the grown material. [ABSTRACT FROM AUTHOR]

Two types of semiconductors, indium phosphide (InP) and silicon (Si), were separately grown on polycrystalline copper foils with the presence of gold colloidal particles. InP was grown with and without carbon deposition by metal organic chemical vapor deposition, and Si was grown with and without plasma enhanced chemical vapor deposition of carbon. While InP and Si grew as films on untreated copper foils, they were found to grow in the form of nanowires when copper foils were pre-treated with carbon. Structural analysis revealed that the grown InP nanowires were polycrystalline. In contrast, the grown Si nanowires were found to have core–shell structures with a monocrystalline core and a polycrystalline shell. Further analysis suggested that graphene was formed on the copper foils during the carbon deposition. Therefore, we concluded that the presence of graphene promoted the growth of InP and Si in the form of nanowires. The demonstration of growing semiconductor nanowires on copper foils could be a new path to integrate semiconductor and metal to provide a unique material platform for a wide range of devices. [ABSTRACT FROM AUTHOR]

We investigated the etching effect of tertiary-butyl chloride (TBCl) during InP nanowire (NW) growth for the purpose of improving the tapering shape at high growth temperature. The vapor-liquid-solid method was performed by using 10-nm-diameter Au particles for NW growth. The InP NW length doubled when TBCl was supplied at the same flow rate as TMIn and decreased gradually with increasing TBCl flow, while the volume monotonically decreased. The TBCl effectively suppressed growth in the radial direction. We also systematically studied the dependence of NW length and volume on growth time, growth temperature, and TMIn flow rate with and without TBCl. The crystalline structure was apparently varied within our growth condition range. At high growth temperature and low TBCl flow rate, the NWs tended to have a wurtzite-based structure. [ABSTRACT FROM AUTHOR]

Indium phosphide and silicon play important and complementary roles in communications wavelength photonic devices. Realizing high quality coalesced epitaxial lateral overgrown (ELO) InP films on Si could greatly reduce cost and encourage the proliferation of energy efficient photonic integrated circuits in consumer devices. By adjusting a parallel line ELO mask and metalorganic vapor phase epitaxial growth conditions, we have fully coalesced and partially coalesced epitaxial lateral overgrowth of InP on InP substrates and Si substrates having strain relaxed III/V buffer layers, respectively. Extended defects were investigated using transmission electron microscopy and were not found to originate at the coalescence of the nearest neighbor growth fronts for linear parallel growth windows oriented 60° off of [0-11] when using a high V/III ratio of 406. In addition, narrowly separated linear parallel growth windows having a large aspect ratio of 7.5 were seen to inhibit the upward propagation of stacking faults through several neighboring openings. Elimination of these two defect sources would leave primarily the challenge of optimizing the morphology of the overgrown InP as a substantial barrier to achieving coalesced ELO InP of sufficient quality for photonic device applications. [ABSTRACT FROM AUTHOR]

Abstract: Novel InP/GaAs1−y Sb y /InP double-heterojunction bipolar transistors (HBTs) with a GaAs spacer between the InP emitter and GaAs1−y Sb y base layer were grown by the metalorganic chemical vapor deposition method in order to simplify the switching sequence for forming a high-quality InP-emitter/GaAs1−y Sb y -base interface. After removal of the InP emitter, the top surface of the GaAs spacer exhibits smooth step-flow-like morphology with root-mean-square roughness of 0.17–0.36nm, whereas the morphology of the GaAs1−y Sb y base of the sample without the GaAs spacer is bumpy. Secondary ion mass spectroscopy reveals that the spacer suppresses the incorporation of excess Sb into the InP emitter around the emitter–base junction. The dependence of the current gain on the thickness of the GaAs spacer is investigated and, when the GaAs spacer is 2nm, the highest current gain is obtained. Therefore, we employ the spacer to scaled-down HBTs with a 0.25-μm-wide emitter. The scaled-down HBTs show high current gain of over 90 at collector current density J C of 10mA/μm2 even though the space between emitter and base electrodes is just 0.15μm. We obtain peak current-gain cut-off frequency of 388GHz and peak maximum oscillation frequency of 290GHz at J C=10mA/μm2. This result suggests that the presence of the GaAs spacer does not impose any penalty on the characteristics at high J C. The insertion of the GaAs spacer is a good way to obtain a high-quality E–B interface with a simple precursor-supply sequence and thereby HBTs with both high-current gain and reasonably high RF performance. [Copyright &y& Elsevier]

Abstract: We have developed a model which integrates calculation of InAlGaAs multiple quantum well (MQW) transition energies using the envelope function approximation with a statistical analysis of the PL emission wavelength, net strain and MQW period measured for a variety of MQW designs grown by MOCVD. The model relates the measured MQW parameters directly to MOCVD process parameters, allowing an accurate prediction of the process parameters required to grow a specified MQW design. This greatly reduces the need to grow and characterize individual calibration layers. The difference of the measured and predicted MQW parameters is recorded run-to-run over time, which allows process variability to be analyzed across a number of process parameters with intentional variations to grow different MQW designs. [Copyright &y& Elsevier]

We present a study of indium phosphide nanowires grown by the selective area vapor liquid solid technique using metalorganic molecular beam epitaxy. Transmission electron microscopy revealed that nanowires grown at a temperature of up to 450°C had a pure wurtzite structure, but at 480°C a mixed wurtzite–zincblend structure was obtained. We also accurately measured the migration length of growth precursors along the side facets of the nanowires by monitoring the length of the non-tapered section of the nanowire adjacent to the gold catalyst. The migration length was found to be of the order of 0.3–0.7µm and to depend on the diameter of the nanowire. Up to the growth temperature of 450°C the migration length was temperature independent, but it increased dramatically to more than 2µm when the nanowires were grown at 480°C. Possible explanations for the observed effects are suggested. [ABSTRACT FROM AUTHOR]

Abstract: Selective area growth (SAG) of single crystalline indium phosphide (InP) nanopillars was demonstrated on an array of template segments composed of a stack of gold and amorphous silicon. The template segments were patterned by UV nanoimprint lithography on a silicon substrate covered with a natural oxide, and the SAG was achieved by metal organic chemical vapor deposition. Our SAG is different from conventional SAG in one critical aspect. In our SAG, growth of InP takes place selectively on a pre-defined array of template segments made of non-single crystal materials on a foreign substrate. The grown InP nanopillars were studied for their structural, chemical and optical properties. The new SAG process is not limited to the specific materials such as InP nanopillars and silicon substrate used in this demonstration; our approach enables flexible and scalable nanofabrication using industrially proven tools and a wide range of semiconductors on various non-semiconductor substrates. [Copyright &y& Elsevier]

Abstract: We report the effects of growth rate on the crystal structure of InP nanowires grown on InP (111)B substrate by metal organic chemical vapour deposition (MOCVD) using gold nanoparticles as catalysts. Results showed that slower growth rate helps to reduce planar defects and the crystal structure changes from wurtzite to zinc-blende with increasing both group III and V precursors flows. Nonetheless, the tapering effect can be reduced with growth rate. High resolution transmission electron microscopy (HR-TEM) confirmed that the crystal structure changes with growth rate. [Copyright &y& Elsevier]

Abstract: This paper reports on carbon (C) doping in InGaAsSb grown on (001) InP substrates by the metalorganic chemical vapor depositions (MOCVD) method using carbontetrabromide (CBr4). The influence of the CBr4 flow rate on the relationships between InGaAsSb alloy compositions and the molar flow ratio of III–V-atom precursors was investigated in C-doped InGaAsSb films. We found that there is nonlinear dependence of the solid In content on the molar flow ratio of group-III precursors for C-doped InGaAsSb. Thermodynamic calculations of the reactions in the InGaAsSb growth process reveal that the characteristic nonlinear dependence is due to the etching reactions of group-III elements with hydrogen bromide, which is generated by CBr4 decomposition. The solid Sb content of both undoped and C-doped InGaAsSb films decreases with increasing molar flow ratio of In precursors due to the preferential incorporations of InAs in In-rich antimonide compounds. On the basis of the obtained knowledge, we have succeeded in growing C-doped InGaAsSb film with a high hole concentration of over 1.0×1019 cm−3, which is useful for the base layer of InP-based heterojunction bipolar transistors. As in C-doped GaAsSb, the effect of hydrogen passivation of C-acceptors in C-doped InGaAsSb is almost negligible. [Copyright &y& Elsevier]

Abstract: A new InP/InGaAs/InP DHBT structure with high carbon (C)-doped base was optimized and grown successfully by gas source molecular beam epitaxy (GSMBE) in this work. The C-doping concentration is 3×1019 cm−3 with carrier mobility of 66.3cm2/Vs. Characteristics of C-doped InGaAs materials were investigated. High quality InP/InGaAs/InP DHBT structural materials were obtained. The InP/InGaAs/InP DHBT device with emitter area of 100×100μm2 was fabricated. The open base breakdown voltage (VBCEO) of 4.2V and current gain of 60 at V CE of 3.0V were achieved. All these results prove the material is suitable for DHBT device fabrication. [Copyright &y& Elsevier]

Abstract: We describe the design, gas-source MBE growth, and performance of a highly strained photovoltaic intersubband detector with peak responsivity between 3 and . The absorbing region is composed of a highly strained InGaAs–InAs–InAlAs–AlAs heterostructure with its average lattice constant matched to InP. The detector design is based on a combination of bound-to-bound and bound-to-continuum transitions, which together allow a broad-band photoresponse, comparable to that of detectors with heterogeneous absorption region. [Copyright &y& Elsevier]

Abstract: Effects of the injector doping densities on lasing properties of mid-infrared InAlAs–InGaAs–InP quantum cascade lasers at 4.3μm have been studied. Lasers with different average injector doping between 1.29E17cm−3 and 2.07E17cm−3 have been grown by gas source molecular beam epitaxy (GSMBE), and their lasing characteristics were investigated. Lasers with low doped injectors (1.68E17cm−3) exhibited lower threshold current density, longer emission wavelength and lower characteristic temperature T 0. The lower injector doping density decreases waveguide loss. On the other hand, the high doping of the injector increases heat transfer through phonon in QCL active region, and thus results in high characteristic temperature T 0. [Copyright &y& Elsevier]

Abstract: We report the fabrication and the characterization of a transistor based on modulation-dope (δ-dope) InAs/InP core shell nanowire which was grown on InAs (111) substrate by VLS techniques using MBE. The mobility of the core shell nanowire was 13,600cm2/Vs at room temperature, which is approximately 7-fold increase comparing to the simple InAs nanowire. Estimated mobility at V ds=0.1V increased from 13,600cm2/Vs at RT to 15,600cm2/Vs at low temperature. A gate voltage dependent crossover from weak-localization to weak-antilocalization was observed. We extracted the spin relaxation length and coherence length using a quasi-one-dimensional model of the conductance. The effectiveness of the InP shell passivation was confirmed. [Copyright &y& Elsevier]

Abstract: We elaborate InP1−x As x quantum dots embedded in InP nanowires by Au-catalyzed molecular beam epitaxy. Each nanowire contains a quantum dot well positioned on its axis and presenting a cylindrical geometry with sharp interfaces. The quantum dot emission wavelength can be tuned in the optical fiber transmission range and the final shape of the nanowire is tailored for efficient wave-guiding and light extraction. These objects, obtained in a single growth run, open a new route to the fabrication of efficient single photon sources. [Copyright &y& Elsevier]

Abstract: The detailed crystalline structure of molecular beam epitaxially grown MnAs thin films on InP(001) substrate has been investigated using high resolution X-ray diffraction techniques. Reciprocal space mapping of the MnAs/InP(001) samples indicates that the MnAs has a cubic zinc-blende (zb) structure with the epitaxial relationship zb-MnAs[110]|InP[110]. The lattice constant of zb-MnAs is ∼6.06Å. The MnAs lattice is relaxed and is mosaic-like likely due to large lattice mismatch between the film and InP substrate. The isotropic nature of the magnetic properties supported our conjecture that the MnAs epitaxial film under study has indeed a cubic structure. [Copyright &y& Elsevier]

Abstract: Type-II InAs/GaSb superlattices are promising for the absorption layers of mid-infrared sensors. Since GaSb substrates absorb infrared light, other substrates with high transparency are favorable for back-illuminated sensors. InP substrate is attractive due to high transparency, relatively small lattice mismatch and near thermal expansion coefficient to silicon CMOS read-out integrated circuit. In this study, type-II InAs/GaSb SLs were successfully grown on InP substrates. The crystalline and optical quality of SL improved as GaSb buffer layer thickness increased due to the reduction of threading dislocations. By using thick GaSb buffer layer, SL with strong PL intensity was successfully obtained. [Copyright &y& Elsevier]

Growth condition dependences of optical properties of InAsSbN single quantum wells (SQWs) grown on InP substrates by molecular beam epitaxy (MBE) for 2-μm-wavelength region were studied. The results for Sb composition dependences indicate that the optimum Sb composition at the growth temperature of 480°C is 2% in the case that the nitrogen composition is 1%. Also, it was found that the PL peak shifts to longer wavelength side with decreasing the growth temperature from 480°C to 450°C, suggesting that the longer wavelength laser operation is possible with the growth temperature of 450°C. In fact, laser operation was achieved for the laser diode structure grown at 450°C. The lasing wavelength is 2.36μm at 220K, which is the longest wavelength for InAsSbN quantum well lasers grown on InP substrates. [ABSTRACT FROM AUTHOR]

Abstract: A variety of metamorphic InGaAs photodetector structures have been grown on InP substrates by gas source molecular beam epitaxy. Their characteristics have been measured by atomic force microscopy, X-ray diffraction and photoluminescence to investigate the effects of growth temperature, grading profile and digital alloy intermediate layers in the buffer. The growth temperature is optimized to linearly decrease during the growth of In x Al1−x As graded buffer, and kept at a relatively high temperature to grow the InGaAs absorption layer. The linearly grading profile of the composition in the buffer is superior to the convex grading profile, which indicates that the grading rate in the beginning could not be too high. The insertion of digital alloy intermediate layers in the In x Al1−x As buffer improves the structural and surface qualities of the photodetector structures, whereas it introduces some negative effects on the optical quality. [Copyright &y& Elsevier]

Abstract: Branched InP nanowires with single crystalline and twinning structure have been successfully synthesized by solvothermal synthesis method using indium powder and white phosphorus as the reactants, cetyltrimethyl ammonium bromide (CTAB) as cationic surfactant and benzene as the solvent at 180°C. Results from XRD suggest that the synthesized sample can be indexed as sphalerite-structured, cubic phase InP with lattice constant of a=5.858Å. We have studied the influences of CTAB and reaction temperatures on the InP wire morphology. Results indicate that these two factors play the important roles in synthesizing the stable and desired patterned nanowires. On the basis of our findings, possible mechanisms are discussed. [Copyright &y& Elsevier]

Abstract: In this paper we present the epitaxial growth and characterization of an InP-based micro-cavity light emitting diode (LED) with up to 3μm light emission by using GaInAs/GaAsSb-based type-II quantum wells. The LED was grown by LP-MOVPE and achieves emission from 2μm to 3μm at room-temperature. Furthermore a second LED with centered emission at 2.8μm has been realized. Hence, the achievable long-wavelength electroluminescence emission with InP-based materials has been extended up to 3μm. [Copyright &y& Elsevier]

Abstract: In this paper we present the first InP-based short-cavity Vertical-Cavity Surface-Emitting Laser with an AlGaInAsP/GaInAsP active region and a re-grown and structured GaAs0.51Sb:C/Ga0.47InAs:Si buried tunnel junction (BTJ), which serves as current aperture, grown by LP-MOVPE. We achieved over 1mW single-mode continuous-wave (cw) emission at around 1.3μm wavelength and room-temperature. The small-signal modulation bandwidth exceeds 7.5GHz, which is appropriate for 10Gb/s data transmission, and the series resistance is as low as 24Ω. The latter value indicates around three times lower dissipated power consumption than comparable MOVPE grown InP-based VCSELs. [Copyright &y& Elsevier]

Abstract: We present microsphere photolithography in combination with wet chemical etching as a fast and low-cost method to produce regular hole arrays in a (100) GaAs surface, which are suitable for controlled nucleation of self-organized InP islands in a metal–organic vapor-phase epitaxy (MOVPE) system. A hexagonal close-packed monolayer of microspheres is used as an array of microlenses to focus UV-light on UV-sensitive photoresist. In this way, regular arrays of holes with spacing can be realized in the photoresist with controllable feature size in the sub- range, which are transferred to a GaAs buffer, using an isotropic etchant. These templates are used to study the site-controlled nucleation of InP islands on a Ga0.51In0.49P barrier. For this purpose the subsequent overgrowth of the templates with a GaAs buffer layer and the GaInP barrier is investigated previous to the additional deposition of the InP. The template quality is monitored during structuring and overgrowth experiments using atomic force microscopy (AFM). Preferred nucleation of InP islands inside the almost filled holes can be observed for uncapped samples. The correlation between the initial patterning and the optical signal of the InP islands is investigated by micro-photoluminescence (micro-PL) measurements. We observe site-controlled nucleation of large, but optically active, InP islands on these templates. [Copyright &y& Elsevier]

Abstract: In this work, selective area growth has been used for the realization of InP based photonic integrated circuits (PICs). To predict the strain, thickness and bandgap energy variations over large and high-density multifunctional arrays, it is necessary to precisely design the shapes and positions of the dielectric masks by computational modeling. To address the mask layout density and complexity in both longitudinal and transversal direction, the use of three dimensional vapor phase model was mandatory. In each SAG region used for individual component processing, the calculated data were compared to experimental ones acquired by synchrotron-based microbeam x-ray diffraction and by micro-photoluminescence wavelength mapping. The excellent result concordance shows that both advanced modeling and characterization techniques are of importance for PIC conception and fabrication. [Copyright &y& Elsevier]

Abstract: The purpose of this study is to establish a crystal growth technique for quantum wells on InP(110) substrates for spintronics devices operating at 1.55μm. This paper reports attempts to optimize growth conditions for InGaAs and InAlAs crystals and their heterostructures on InP(110) and vicinal substrates in molecular beam epitaxy. For crystal growth on InP(110) substrates, the crystal quality of InGaAs/InAlAs quantum wells deteriorated in spite of fabrication in optimized conditions for each of the InGaAs and InAlAs homo-epitaxial layers. A significant number of defects on the plane were observed in transmission electron microscope (TEM) images; these defects started from the InAlAs buffer and barrier layers. For InP(110) vicinal substrates, we used substrates tilted by 3° from the exact (110) orientation toward (100), (010), (111)A and (111)B poles. We describe the optimized InGaAs/InAlAs quantum wells on InP(110) substrates tilted by 3° toward the (111)B pole. The TEM observation clearly showed the improvement in crystal quality. We also measured absorption spectra of the InGaAs/InAlAs quantum wells. [Copyright &y& Elsevier]

Abstract: Indium phosphide (InP) films were deposited onto glass substrates using RF magnetron sputtering by varying the substrate temperature (348–573K), under constant argon pressure (0.4Pa) and RF power (150W). Substrate temperature found to have significant influence on the composition, structure, morphology, electrical and optical properties of InP films. Single phase, nearly stoichiometric and polycrystalline films exhibiting zinc blende structure with strong preferred orientation along (111), was observed for the films grown at a substrate temperature of 448K. Conical shaped grain growth was observed in the grown films. Hall measurements revealed n-type conductivity in the InP films. The optical absorption studies indicated a direct band gap of 1.35eV. Various lattice vibrational modes observed by Raman measurements were found to match well with those reported for single-crystal InP. [Copyright &y& Elsevier]

Abstract: We study diffusion of zinc into InP in a multiwafer OMVPE reactor using dimethylzinc as the diffusant source. The resulting diffusion profiles are measured by electrochemical capacitance–voltage profiling and by secondary ion mass spectrometry and compared with cleaved cross-sections imaged by scanning electron microscopy. Very good uniformity of the diffusion profile is achieved, with variation across a 3in. wafer as little as 5%. The dependence of the diffusion depth and Zn concentration on the diffusion temperature, partial pressure of dimethylzinc, and diffusion time are reported. We observe an enhancement of the diffusion depth in area-selective diffusion of planar devices, compared to the depth obtained for blanket diffusion. [Copyright &y& Elsevier]

Abstract: InP/Gd2O3 heterostructures have been prepared by molecular beam epitaxy of Gd2O3 on InP nanowires grown on silicon substrates by molecular beam epitaxy assisted with the vapor–liquid–solid method. Transmission electron microscopy showed Gd2O3 nanocrystals, having diameters between 3 and 7nm, decorating the sidewalls of InP nanowires. No epitaxial relationship was observed between Gd2O3 nanocrystals and InP nanowires due an amorphous interfacial layer. Depending on the Gd2O3 growth temperature, two morphologies have been highlighted. For Gd2O3 grown at 30°C, anisotropic heterostructures made of oxide nanocrystals covering just one side of the nanowires were observed, while at 250°C Gd2O3/InP core/shell nanowires were identified. [Copyright &y& Elsevier]