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Strain and stress were simulated using finite element method (FEM) for three III–V-on-Insulator (III–VOI) structures, i.e., InP/SiO2/Si, InP/Al2O3/SiO2/Si, and GaAs/Al2O3/SiO2/Si, fabricated by ion-slicing as the substrates for optoelectronic devices on Si. The thermal strain/stress imposes no risk for optoelectronic structures grown on InPOI at a normal growth temperature using molecular beam epitaxy. Structures grown on GaAsOI are more dangerous than those on InPOI due to a limited critical thickness. The intermedia Al2O3 layer was intended to increase the adherence while it brings in the largest risk. The simulated results reveal thermal stress on Al2O3 over 1 GPa, which is much higher than its critical stress for interfacial fracture. InPOI without an Al2O3 layer is more suitable as the substrate for optoelectronic integration on Si. [ABSTRACT FROM AUTHOR]

GaAs1−xBix/AlGaAs quantum wells (QWs) with varying As/Ga beam equivalent pressure (BEP) ratios were grown by solid source molecular beam epitaxy at a relatively high temperature of 350–400 °C intended for light emitting applications with wavelengths beyond 1.2 μm. Both the Bi content and the photoluminescence (PL) intensity were found to be highly dependent on As2 flux, especially for the case of growing GaAsBi at a relatively high temperature. A graded index separate confinement GaAsBi/AlGaAs single QW with 5.8% Bi exhibited a strong PL emission at 1.22 μm. The growth strategy to incorporate considerable Bi into GaAs at a relatively high temperature through meticulous control of the As/Ga BEP ratio and compensation of Bi flux is demonstrated to be effective in guaranteeing a high Bi content as well as an optimal optical performance of GaAsBi QWs. [ABSTRACT FROM AUTHOR]

Carbon-doped InGaAsBi films on InP/Fe (100) substrates have been grown by molecular beam epitaxy (MBE). It has been found that Bismuth incorporation induces extremely high n-type carbon-doped InGaAsBi films, and its electron concentration increases linearly up to 10 cm (highest reported to date for n-type III-V semiconductor materials) with increased CBr supply pressure, implying InGaAsBi to be a prospective ohmic contact material for InP-based terahertz transistors. It also has been proved by secondary ion mass spectroscopy that the alloy composition of carbon-doped InGaAsBi is altered by the preferential etching effect of CBr, but the etching effect on the Bi content is negligible. [ABSTRACT FROM AUTHOR]

Bi2Te3 has drawn great attention in recent years as both a topological insulator and the best thermoelectric material at room temperature. We report on Raman spectroscopic study on Bi2Te3 thin films with thicknesses of 20–50 nm grown on GaN by molecular beam epitaxy. All the four classical optical phonon modes are clearly revealed for the first time in ex situ Raman for epitaxial Bi2Te3. Unusual and infrared-active vibration modes are also observed and analyzed. In the resonant Raman measurements, abnormal enhancement and suppression of different modes are studied. The interface modes caused by a large density of domain boundaries formed during coalescence of crystal islands with different lattice orientations and the Fröhlich electron–phonon interaction are found to play significant roles during the Raman scattering processes. [ABSTRACT FROM AUTHOR]

Abstract: Molecular beam epitaxy growth for InSb1−x Bi x thin films on (100) GaAs substrates is reported. Successful Bi incorporation for 2% is achieved, and up to 70% of the incorporated Bi atoms are at substitutional sites. The effects of growth parameters on Bi incorporation and surface morphology are studied. Strong In and Ga inter-diffusion induced by Bi incorporation is observed and discussed. [Copyright &y& Elsevier]

Molecular beam epitaxy for GaSb1-xBix is investigated in this article. The growth window for incorporation of Bi in GaSb was found. Strategies of avoiding formation of Bi droplets and enhancing Bi incorporation were studied. The Bi incorporation was confirmed by SIMS and RBS measurements. The Bi concentration in the samples was found to increase with increasing growth temperature and Bi flux. The position of GaSb1-xBix layer peak in XRD rocking curves is found to be correlated to Bi composition. Surface and structural properties of the samples were also investigated. Samples grown on GaSb and GaAs substrates were compared and no apparent difference for Bi incorporation was found. [ABSTRACT FROM AUTHOR]

Abstract: Strong enhancement of photoluminescence intensity from InGaAs quantum wells by incorporating nitrogen in metamorphic InGaAs buffers grown on GaAs substrates was demonstrated and investigated. The enhancement of photoluminescence intensity is found to be from both the weak strain effect and the strong lattice hardening effect, indicating blocking effect of threading dislocations due to the N incorporation. Combination of this method with a strain compensated superlattice was proved to be effective in obtaining good quality metamorphic InGaAs quantum wells. [Copyright &y& Elsevier]

CdSe/CdTe superlattices are grown on GaSb substrates using molecular beam epitaxy. X-ray diffraction measurements and cross-sectional transmission electron microscopy images indicate high crystalline quality. Photoluminescence (PL) measurements show the effective bandgap varies with the superlattice layer thicknesses and confirm the CdSe/CdTe heterostructure has a type-II band edge alignment. The valence band offset between unstrained CdTe and CdSe is determined as 0.63 ± 0.06 eV by fitting the measured PL peak positions using the envelope function approximation and the Kronig-Penney model. These results suggest that CdSe/CdTe superlattices are promising candidates for multi-junction solar cells and other optoelectronic devices based on GaSb substrates. [ABSTRACT FROM AUTHOR]

The structural properties of GeSn thin films with different Sn concentrations and thicknesses grown on Ge (001) by molecular beam epitaxy (MBE) and on Ge-buffered Si (001) wafers by chemical vapor deposition (CVD) were analyzed through high resolution X-ray diffraction and cross-sectional transmission electron microscopy. Two-dimensional reciprocal space maps around the asymmetric (224) reflection were collected by X-ray diffraction for both the whole structures and the GeSn epilayers. The broadenings of the features of the GeSn epilayers with different relaxations in the ω direction, along the ω-2θ direction and parallel to the surface were investigated. The dislocations were identified by transmission electron microscopy. Threading dislocations were found in MBE grown GeSn layers, but not in the CVD grown ones. The point defects and dislocations were two possible reasons for the poor optical properties in the GeSn alloys grown by MBE. [ABSTRACT FROM AUTHOR]

Delta doped GaSbBi quantum wells (QWs) grown by molecular beam epitaxy was investigated to extend light emission wavelength at room temperature with the Bi content of 7.0%. The delta-doped GaSbBi QWs transition energy shifts up to 47.0 meV with increasing the Te dopant concentration from 0 to 4.56 × 10 12  cm −2 , resulting in maximum light emission of 2.42 μm, without obvious degradation of optical quality. The temperature coefficient of the band-gap for the delta-doped QW is only 0.099 meV/K compared with 0.265 meV/K from the undoped GaSbBi reference QW. [ABSTRACT FROM AUTHOR]

Epitaxial growth of GaSb 1– x Bi x thin films on GaSb (100) substrates were studied by varying V/III ratio, growth temperatures and Bi flux using molecular beam epitaxy. It is demonstrated that reducing the V/III ratio facilitates Bi incorporation into GaSb effectively. The highest average Bi content up to 11% with locally up to 13% is achieved, confirmed by Rutherford backscattering spectroscopy and transmission electron microscopy (TEM). X-ray diffraction and TEM show perfect crystal quality for the GaSb 1– x Bi x film with x  = 5.6%. The composition dependence room temperature photoluminescence (PL) spectra of the GaSb 1– x Bi x alloys with 0 <  x  ≤ 13% are reported for the first time. The band-gap energy decreases effectively with increasing the Bi content and in the range of 1 ≤  x  ≤ 5.6%, the linear decreasing rate is 37 meV/Bi%. For the highest Bi content GaSb 1– x Bi x , the PL peak energy reaches 0.41 eV (3.0 μm), indicating that GaSb 1– x Bi x alloy has potentials in mid-infrared optoelectronic applications. [ABSTRACT FROM AUTHOR]

In this work, the In 1−y Ga y As 1−x Bi x epilayers were optimized and grown successfully by V90 gas source molecular beam epitaxy (GSMBE). The effect of using an In 0.53 Ga 0.47 As buffer layer on the crystalline quality of In 1−y Ga y As 1−x Bi x epilayers were investigated. With the buffer layer preparation, the surface RMS roughness value of 0.251 nm, a maximum electron mobility of 5700 cm 2 /Vs and a bulk carrier density of 2.9 × 10 16 cm 3 are achieved for the In 1 − y Ga y As 1 − x Bi x epilayer with the Bi content up to 3.1%. [ABSTRACT FROM AUTHOR]

The effects of Bi, In flux and PH 3 pressure on Bi incorporation, structural and transport properties of InPBi grown by gas source molecular beam epitaxy have been systematically studied. Incorporation of Bi behaves like a dopant and its content increases linearly with Bi flux and inversely with the InP growth rate (In flux), and is independent of the PH 3 pressure studied. High PH 3 pressure causes rough surface and introduction of Bi improves surface quality. Intrinsic InP grown at a low temperature reveals n -type due to the P In antisite defects and the electron density is proportional to the PH 3 pressure and inversely proportional to the InP growth rate. Incorporation of Bi induces p -type dopant that compensates the background electron concentration but doesn't degrade the electron mobility for the Bi content up to 2.4%. These results suggest that there is still a large room left to optimize material quality and maximize Bi incorporation in InPBi using gas source molecular beam epitaxy. [ABSTRACT FROM AUTHOR]

• The effects of substrate temperature on the epilayer uniformity are investigated. • The temperature setting of the manipulator with dual-zone heaters is optimized. • The composition fluctuation is less than ±0.1% across the 3-inch InGaAs epilayer. • A relatively high substrate temperature can effectively reduce the growth impurities. Three-inch InGaAs epilayers are grown by solid source molecular beam epitaxy using the manipulator equipped with dual-zone heaters. The effects of the substrate temperature on the uniformity of material surface morphology, indium composition, photoluminescence, electronic mobility, and background doping are investigated. As the temperature of the outer heater in the range of 625 °C to 655 °C, no dim area is observed on the edge of the material surface. At the same time, the indium composition fluctuation of the high-resolution X-ray diffraction and the photoluminescence wavelength fluctuation are less than ±0.1% for the epilayers grown at the optimum substrate temperatures. [ABSTRACT FROM AUTHOR]

GaSb 1-x Bi x thin film was grown on a 2 inch GaSb substrate by molecular beam epitaxy (MBE) without substrate rotation. Bi composition is found to vary from 2.76% to 3.98% across the wafer. The distribution of Bi content is mainly determined by spatial non-uniformity of Sb/Ga flux ratio, while Bi flux has slightly influence. Ostwald ripening process is confirmed to be reason for bigger Bi droplets via Bi surface diffusion. With the increase of Sb/Ga flux ratio, Ostwald ripening process is suppressed. At high Bi flux, excess Ga atoms accumulate on surface and form droplets. • Ostwald ripening of Bi droplets via Bi surface diffusion is confirmed. With the increase of Sb/Ga flux ratio, the Bi diffusion length decreases and Ostwald ripening is suppressed. • Ga droplets co-exist with the Bi droplets and their density increases with the decrease of the Sb/Ga flux ratio and the increase of the Bi flux. [ABSTRACT FROM AUTHOR]