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Electron cyclotron resonance (ECR) plasma etching with additional rf-biasing produces etch rates ≥ 2,500 A/min for InGaP and AlInP in CH4/H2/Ar. These rates are an order of magnitude or much higher than for reactive ion etching conditions (RIE) carried out in the same reactor. N2 addition to CH4/H2/Ar can enhance the InGaP etch rates at low flow rates, while at higher concentrations it provides an etch-stop reaction. The InGaP and AlInP etched under ECR conditions have somewhat rougher morphologies and different stoichiometries up to ≈200 A from the sur face relative to the RIE samples.

Etch rates above 1 μm min−1 are achieved for InGaP and AlInP under electron cyclotron resonance conditions in low pressure (1.5 mTorr) Cl2/Ar discharges. Much lower rates were obtained for AlGaP due to the greater difficulty of the bond breaking that must precede formation and desorption of the etch products. The etched surface morphology and stoichiometry are strong functions of the plasma composition (i.e., the ion/neutral flux ratio). Under optimal conditions, there are no detectable chlorine related residues, in sharp contrast to reactive ion etching with this plasma chemistry.

Etch rates above have been obtained for and plasma etching of , and under electron cyclotron resonance (ECR) conditions. The etched surface morphologies are a strong function of the ratio of chlorine radicals to total ion density in the discharges, and are smoother in . Non-optimized etching conditions produce rough surfaces characterized by the presence of chlorine and boron-containing residues and substantial post-oxidation. We believe that the high ion flux available under ECR conditions provides efficient sputtering of the normally involatile , and thus a selvedge layer of this material is prevented from forming. Therefore the etch rates are much higher and the surface morphologies smoother in ECR discharges. The etch rates of are much lower than the other two ternary compounds and are independent of composition over the range x = 0.05 - 0.70 for fixed plasma conditions.

InP, InAlP and InGaP can be etched at rates of 0.5–0.8 μm min−1 in pure BCl3 discharges at high microwave powers (1000 W). The etch rates are strong functions of focusing magnet current, microwave power, sample temperature and to the nature of additive gases. For example, InGaP etch rates a factor of two to three faster than for BCl3 alone are obtained when small additions (25% by flow) of N2 or O2 are added to enhance dissociation of the BCl3. As microwave power is increased the surface morphology of InP is degraded, while that of InGaP improves, InAlP is relatively resistant to surface changes between 250 and 1000 W of microwave power. The sidewalls of etched features are extremely smooth and suitable for a variety of photonic devices.

Hydrogen passivation of Zn acceptors and Si donors in In 0.49 Ga 0.51 P layers has been examined as a function of the microwave power (0–1000 W) and process pressure (1–10 mTorr) of electron cyclotron resonance H 2 discharges. The dopant passivation is much stronger in p-type InGaP than in n-type materials for all plasma conditions, which we ascribe to the more stable bond-centred position for hydrogen in p-InGaP. Reactivation of the passivated dopants begins at ⩽ 300 °C and is complete by 400 °C in n-type material and 450 °C in p-type material.

An optical pumping study was carried out to measure the characteristic times governing the polarization of the photoluminescence in GaAs grown either on InP or on Si, using excitation energies close to the optical transitions. It was shown that the use of the common assumption of a complete hole-spin relaxation is appropriate when dealing with the quasi resonant excitation of the transition involving the sole | 3 2 , ± 1 2 > hole states. The spin-relaxation times measured from the data are in the order of 50 ps. To explain our observations for the transition involving the | 3 2 , ± 3 2 > hole states, the luminescence of which is always observed, even at liquid helium temperature, it is necessary to consider an incomplete hole-spin relaxation.

InGaAs-GaAs separate confinement, heterostructure single quantum-well (SCH-SQW) lasers (/spl lambda/=0.98 /spl mu/m) with lattice-matched InGaP cladding layers, using a new Ga/sub 2/O/sub 3/ low reflectivity (LR) front-facet coating, are reported. The CW peak power density (17 MW/cm/sup 2/) of 6 /spl mu/m/spl times/750 /spl mu/m ridge-waveguide lasers is limited by thermal rollover, and repeated cycling beyond thermal rollover produced no change in operating characteristics. The high-power temperature distribution along the active stripe has been measured by high-resolution infrared (3-5 /spl mu/m) imaging microscopy. The temperature profile acquired for a very high optical power density P/sub D/=11 MW/cm/sup 3/ was found to be uniform along the inner active laser stripe, and revealed a local temperature increase at the LR front facet /spl Delta/T/sub f/ of only 9 K above the average stripe temperature /spl Delta/T/sub s/=24 K. An excellent front-facet interface recombination velocity >

High-density, magnetically enhanced discharges of Cl2/CH4/H2/Ar were shown to provide rapid dry etching of InGaAsP/InP laser structures for sample temperatures of greater than 130 ‡C. The etch rates were ~1 Μm min−1, and they were more than an order of magnitude faster than for conventional CH4/H2/Ar etching. Smooth, anisotropic mesa sidewalls were obtained when the direct-current (d.c.) self-bias was kept low (−80 V). The etched surfaces were suitable for epitaxial regrowth of current-blocking layers by either organo-metallic-vapour-phase epitaxy or metal-organic molecular-beam epitaxy. In the former technique, addition of CCl4 to the growth chemistry was helpful in preventing deposition of polycrystalline InP on the dielectric mask.

The carbon-doping behavior of GaAs and AlGaAs grown by organometallic vapor phase epitaxy was examined using AsH3 or tertiarybutylarisine (TBAs) as the arsenic precursors. Carbon tetrachloride was utilized as the carbon dopant precursor for GaAs and AlGaAs. In addition, the intrinsic carbon doping of AlGaAs was also examined for these two As sources. The use of TBAs led to a significant reduction in carbon incorporation, by approximately a factor of 5–10 per mole of As precursor, both with respect to extrinsic and intrinsic carbon incorporation. For the GaAs:C layers grown at temperatures ⩽550°C, significant concentrations ( 10−6 × 10 19 cm −3 ) of hydrogen were detected. Approximately 25–55% of the carbon acceptors were passivated by the hydrogen, based on Hall measurements and infrared absorption measurements. The CCl4 source introduced oxygen into the AlGaAs layers. TBAs was more effective in reducing oxygen incorporation compared to AsH3 and the concentration of oxygen was reduced with either increasing TBAs or AsH3 flow rate.

Dry etching is used for a number of processing steps in the fabrication of small geometry (∼2×5 μm2 emitter dimension), high speed (fT, fmax≥50 GHz) heterojunction bipolar transistors, including emitter, base, and collector mesa definition, sidewall etch‐back, and trilevel resist patterning. These steps involve the use of numerous plasma chemistries (CCl2F2 or BCl3 for GaAs/AlGaAs, CH4/H2 for InGaAs/InP, SF6 for dielectric sidewalls, and O2 for resist). We have conducted a systematic study of the threshold dc self‐biases for these discharges below which there is no significant damage introduction in the semiconductor. In a low pressure hybrid electron cyclotron resonance‐radio frequency reactor, these biases are a function of the doping type, doping level and the thickness of the exposed III–V layers. Changes in the sheet resistance and diode ideality factor of p–n junctions in each material system were examined as a function of the time (1–20 min), plasma pressure (1–20 mTorr), and additional rf‐induced ...

Electron cyclotron resonance (ECR) BCl3 discharges with additional rf biasing of the sample position have been used to etch a variety of III–V semiconductors. GaAs and AlxGa1−xAs (x = 0−1) etch at equal rates in BCl3 or BCl3/Ar discharges, whereas SF6 addition produces high selectivities for etching GaAs over AlGaAs. These selectivities are in excess of 600 for dc biases of ≤−150 V, and fall to ≤6 for biases of −300 V. If the dc biases are kept to ≤ − 100 V, there is no measurable degradation of the optical properties of the GaAs and AlGaAs. The AlF3 formed on the AlGaAs surface during exposure to BCl3/SF6 plasmas can be removed by sequential rinsing in dilute NH4OH and water. In-based materials (InP, InAs, InSb, InGaAs) etch at slow rates with relatively rough morphologies in BCl3 plasmas.

Vinyl iodide (C2H3I) microwave discharges with additions of H2 and Ar are found to provide faster etch rates than conventional CH4/H2/Ar discharges for InP, InGaAs, GaAs, and AlGaAs. This is a result of the relatively high volatilities of indium, gallium, and aluminum iodide species. The etched features are smooth and anisotropic over a wide range of do self-biases (−150 to −350 V), process pressures (1–20mTorr), and microwave powers (150–500 W). The polymer that forms on the mask during the plasma exposure can be readily removed in O2 discharges. Electron spectroscopy for chemical analysis (ESCA) showed that the etched surfaces are slightly deficient in the group V elements under most conditions, but changes to the optical properties of the semiconductors are minimal. No defects are visible by transmission electron microscopy (TEM) in GaAs or InP samples etched at dc biases ≤ −250 V.

Electron cyclotron resonance (ECR) discharges of HBr/Ar, HBr/H 2 , or HBr/CH 4 were used for dry etching of Ga-based (GaAs, GaSb, and AlGaAs) and In-based (InP, InAs, InSb, InGaAs, and InAlAs) III-V semiconductors. The effects of variations in pressure (1-20 mTorr), gas composition, and additional RF-induced bias on the sample were examined. At least -100 V of dc bias is required to initiate etching under all conditions, with the etch rates found to be fastest with CH 4 addition, followed by H 2 and then Ar

Ar inductively coupled plasmas (ICP) are found to produce substantially less ion-induced damage to AlGaAs than electron cyclotron resonance plasmas with the same average ion energy. The dc self-bias and hence ion energy is strongly suppressed by increasing ICP source power, while ion flux increases by approximately two orders of magnitude between source powers of 0 and 1500 W. The changes in AlGaAs sheet resistance are due primarily to introduction of deep level compensating defects which reduce both carrier density and mobility.

We present a detailed and thorough study of a wide variety of quantum well infrared photodetectors (QWIPs), which were chosen to have large differences in their optical and transport properties. Both n- and p-doped QWIPs, as well as intersubband transitions based on photoexcitation from bound-to-bound, bound-to-quasi-continuum, and bound-to-continuum quantum well states were investigated. The measurements and theoretical analysis included optical absorption, responsivity, dark current, current noise, optical gain, hot carrier mean free path; net quantum efficiency, quantum well escape probability, quantum well escape time, as well as detectivity. These results allow a better understanding of the optical and transport physics and thus a better optimization of the QWIP performance.

In this paper we will describe the use of various plasma etching techniques in III–V semiconductor technology. The fabrication of a typical device involves a sequence of patterning, etching and deposition steps. The trend is toward the use of dry etching whenever possible because of the more anisotropic features and better dimensional control that can be obtained. This approach is consistent with an integrated processing concept in that plasma etching is a vacuum technique, and the dry etch reactor chamber can be coupled with other deposition, annealing or epitaxial growth chambers via load locks and transfer arms.

High performance quantum well infrared photodetectors (QWIPs) have been grown using metalorganic chemical vapor deposition. Detailed optical and electrical measurements as a function of growth temperature TG, show that the best quality samples were grown at the highest temperature tried,i.e. T G = 700°C.

Atomic hydrogen is shown to be unintentionally incorporated into GaAs, AlGaAs, InP and related compounds during gas source epitaxial growth and subsequent processing steps. During growth, the origin of the hydrogen may be the group V source (AsH 3 or PH 3 ), the growth III source ( e.g. trimethylgallium) or the H 2 carrier gas. Boiling of the III–V materials in water or wet chemical etching steps both lead to bear-surface dopant passivation which is confirmed to be due to hydrogen by secondary ion mass spectrometry profiling. Dry etching in hydrogen-containing plasmas ( e.g. CH 4 H 2 or CH 3 Cl) leads to substantial dopant passivation, and this can occur even when hydrogen is not a specific part of the plasma chemistry because of the presence of water vapor or photoresist mask erosion. Hydrogen also readlly permeates into III–V materials during annealing at moderate temperatures (450 °C and above) in H 2 -containing ambients.

Electron cyclotron resonance (ECR) discharges of HBr/Ar, HBr/H 2 , or HBr/CH 4 were used for dry etching of Ga-based (GaAs, GaSb, and AlGaAs) and In-based (InP, InAs, InSb, InGaAs, and InAlAs) III-V semiconductors. The effects of variations in pressure (1-20 mTorr), gas composition, and additional RF-induced bias on the sample were examined. At least -100 V of dc bias is required to initiate etching under all conditions, with the etch rates found to be fastest with CH 4 addition, followed by H 2 and then Ar

Results of an extensive study of the interfacial intermixing and interaction of the Pt/Ti bilayer metallization to seven III-V binary and related ternary compound semiconductor systems, as well as the contact electrical properties, are given. Pt/Ti contact to InAs and In/sub 0.53/Ga/sub 0.47/As were ohmic as deposited, while the same metallization scheme on GaAs, GaP, InP, In/sub 0.52/Al/sub 0.48/As, and Ga/sub 0.7/Al/sub 0.3/As provided a rectifying contact as-deposited. The latter group of contacts, with the exception of InP and GaP, were transformed to an ohmic contact as a result of rapid thermal processing (RTP) at the temperature range of 300 to 450 degrees C. A linear correlation between the semiconductor bandgap value and the Schottky-barrier height, measured in the Pt/Ti contacts, was observed. >

The use of rapid isothermal processing (RIP) is detailed for each of the three annealing steps in the fabrication of heterostructure-based devices such as heterojunction bipolar transistors (HBTs). RIP can be used for the alloying of ohmic metal contacts, annealing of ion-bombarded regions for device isolation or parasitic capacitance reduction, and for conventional implant activation annealing. High-speed (f/sub T/=65 GHz) HBTs were achieved using RIP for all of the required heating steps. The authors compare the use of several types of silicon carbide-coated graphite susceptors for eliminating slip formation on 2- and 3-in-diameter GaAs wafers during high-temperature implant activation annealing. >

The effects of hydrogenation on the 1.7K optical pumping properties of GaAs grown on InP substrate by metalorganic chemical vapor deposition are investigated in the (1.616 – 2.032 eV) excitation energy range. The optical pumping effects observed on the two transitions involving electrons and M J = ± 1 2 or M J = ± 3 2 holes suggest incomplete hole spin depolarization. These results are compared with those obtained on intentionally undoped GaAs/Si samples.

A systematic study has been performed of the dry etching characteristics of GaAs, Al0.3Ga0.7As, and GaSb in chlorine-based electron cyclotron resonance (ECR) discharges. The gas mixtures investigated were CCl2F2/O2, CHCl2F/O2, and PCl3. The etching rates of all three materials increase rapidly with applied RF power, while the addition of the microwave power at moderate levels (150 W) increases the etch rates by 20–80%. In the microwave discharges, the etch rates decrease with increasing pressure, but at 1 m Torr it is possible to obtain usable rates for self-bias voltages ≤ 100 V. Of the Freon-based mixtures, CHCl2F provides the least degradation of optical (photoluminescence) and electrical (diode ideality factors and Schottky barrier heights) properties of GaAs as a result of dry etching. Smooth surface morphologies are obtained on all three materials provided the microwave power is limited to ≤ 200 W. Above this power, there is surface roughening evident with all of the gas mixtures investigated.

Electron cyclotron resonance (ECR) discharges are characterized by low ion energies ( ≤ 15 eV) and high densities of active species. This makes them excellent candidates for high rate, low damage dry etching of III–V semiconductors. We have investigated the use of ECR discharges of CH4/H2/Ar for etching InP, InGaAs, AlInAs and GaAs as a function of additional rf biasing of the sample, and in this article present the InP results. In contrast to the results with conventional reactive ion etching (RIE), ECR discharges lead to very shallow (~ 20 A) damaged layers on these materials and much less disruption of the electrical quality of the etched surface. For example, RIE of InP leads to nonstoichiometric, In-rich surfaces to which one cannot make a Schottky contact. Removal of at least 150 A of material is required before the integrity of the surface is restored. We have been able to achieve excellent rectifying contacts on ECR-etched InP without the need for wet chemical treatment of the surface. Optical and chemical analysis of the ECR etching shows that it clearly is a low damage process relative to the more conventional dry etch methods.

The reactive ion etching of GaAs, InP, InGaAs, and InAlAs in CF3Br/Ar discharges was investigated as a function of both plasma power density (0.56-1.3 W - cm−2) and total pressure (10-40 mTorr) The etch rate of GaAs in 19CF3Br:1Ar discharges at 10 m Torr increases linearly with power density, from 600 A min−1 at 0.56 W · cm−2, to 1550 A · min at 1.3 W · cm−2. The in-based materials show linear increases in etch rates only for power densities above − 1.0 W · cm−2. These etch rates are comparable to those obtained with CCI2F2:O2 mixtures under the same conditions. Smooth surface morphologies and vertical sidewalls are obtained over a wide range of plasma parameters. Reductions in the near-surface carrier concentration in n-type GaAs are evident for etching with power densities of >0.8 W cm−2, due to the introduction of deep level trapping centers. At 1.3 W· cm−2, the Schottky barrier height of TiPtAu contacts on GaAs is reduced from 0.74 to 0.53 eV as a result of this damage, and the photoluminescent intensity from the material is degraded. Alter RIE, we detect the presence of both F and Br on the surface of all of the semiconductors. This contamination is worse than with CCl2F2-based mixtures. High-power etching with CF3Br/Ar together with Al-containing electrodes can lead to the presence of a substantial layer of aluminum oxide on the samples if the moisture content in the reactor is appreciable.

We report the use of a Mo barrier layer within Ni/Au-Ge based ohmic contacts to GaAs for eliminating an etch stop reaction that occurs during Cl-based dry etching of heterojunction bipolar transistors. With conventional Ni/Au-Ge/Ag ohmic contacts, chlorinecontaining discharges produce a passivating layer of AgCl on the semiconductor surface, preventing further etching. This layer is absent when the Ag in the contact is replaced with Mo. The Mo has several advantages over other diffusion barrier layers and yields contacts with excellent adhesion, smooth morphology, and sharp edge definition. The average contact resistivity of these contacts ton +-GaAs(n = 6 × 1018 cm-3) was 0.074 ohm-mm, which is lower than the typical contact resistivity of conventional Ni/Au-Ge/ Ag metallization (0.11 ohm-mm).

We have fabricated vertical-cavity surface-emitting lasers (VCSELs) which, for the first time, effectively combine a shallow ion implanted aperture, for current confinement under a thin highly conducting lateral current injection layer, and an independent index guide for optical beam confinement (I/sup 2/-VCSELs). Both features are possible only because they are made before a top dielectric mirror is deposited and patterned, and are photolithographically defined for improved size reproducibility compared to oxide-confined designs. The devices emit near 980 nm and have optical power outputs of 1 mW at 2.5-mA input. The 12-VCSEL design also easily incorporates coplanar contacts allowing us to operate flip-chip bonded I/sup 2/-VCSEL's on silicon test chips at data rates of nearly 1 Gb/s.

Recent advances in heterostructure bipolar transistor (HBT) technology have created a need for p-type doping at levels ≥1020 cm-3. We have achieved p-type doping levels as high as 5×1020 cm-3 using C, which is introduced through the use of trimethylgallium (TMG) during metalorganic molecular beam epitaxy (MOMBE) growth of GaAs. By utilizing the atomic planar doping method, we have also been able to grow C-doped spikes with hole concentrations as high as 7×1019 cm-3, with a full width at half maximum of ∼50 A at 300 K. This level is among the highest reported for planar doping. By switching out the TMG, and switching in the triethylgallium (TEG) to continue to growth of C-free GaAs, we have grown sandwich-type structures with C levels of 1020 cm-3, which fall off within 210 A to C levels of

Ar inductively coupled plasmas (ICP) are found to produce substantially less ion-induced damage to AlGaAs than electron cyclotron resonance plasmas with the same average ion energy. The dc self-bias and hence ion energy is strongly suppressed by increasing ICP source power, while ion flux increases by approximately two orders of magnitude between source powers of 0 and 1500 W. The changes in AlGaAs sheet resistance are due primarily to introduction of deep level compensating defects which reduce both carrier density and mobility.

Small signal direct modulation characteristics of InGaAs-GaAsP-InGaP multiple quantum well ridge waveguide lasers (4.5/spl times/220 /spl mu/m/sup 2/) are described. The compressive strain of four InGaAs quantum wells is compensated by the tensile strain of GaAsP barriers. The lasers have a threshold current of 8 mA and an internal differential quantum efficiency of 80%. A 3-dB bandwidth of 25 GHz is obtained at 54 mA. It is found that the strain-compensated lasers have a K factor as low as 0.15 ns, implying a maximum 3-dB bandwidth of 59 GHz.

The performance characteristics of InGaAs-GaAsP-InGaP strain compensated laser emitting near 1 /spl mu/m are reported. The ridge waveguide lasers have room temperature threshold current of 18 mA and differential quantum efficiency of 0.45 W/A/facet. The linewidth enhancement factor is smaller and gain coefficient is larger for these strain compensated lasers compared to that for conventional strained layer laser. This may be due to higher effective compressive strain in the light emitting layer of these devices which reduces the effective mass. The observed larger gain coefficient is consistent with the measured larger relaxation oscillation frequency of these lasers compared to that for a conventional strained layer laser.

A method for modulation of semiconductor lasers is demonstrated. The method is based on the modulation of the optical confinement factor. Using this method an enhanced—3-dB bandwidth is observed in agreement with the small signal rate equation analysis. A modulation response that drops at high frequencies slower than the conventional direct current modulation response is achieved. This supports the theoretical predictions, showing an intrinsic 1/f decay rate for the optical confinement factor modulation scheme versus an intrinsic 1/f2 decay for direct modulation.

The electrical properties of AlxGa1−xAs (0≤x≤0.44) grown by organometallic vapor phase epitaxy using trimethylamine alane as the Al precursor were investigated. High‐quality AlGaAs Schottky barriers were fabricated and characterized by current–voltage, capacitance–voltage, and deep level transient spectroscopy measurements. The epilayers showed excellent electrical characteristics with low overall trap concentrations. In particular, the AlxGa1−xAs layers contained very low concentrations of EL2.

Finite difference analysis was used to determine the thermal characteristics of continuous wave (CW) 850 nm AlGaAs/GaAs implant-apertured vertical-cavity surface-emitting lasers. A novel flip-chip design was used to enhance the heat dissipation. The temperature rise in the active region can be maintained below 40 °C at 4 mW output power with 10 mA current bias. In contrast, the temperature rise reaches above 60 °C without flip-chip bonding. The transient-temperature during turn-on of a VCSEL was also investigated. The time needed for the device to reach the steady-state temperature was in the range of a few tenths of a milli-second, which is orders of magnitude larger than the electrical or optical switch time. Flip-chip bonding will reduce the shift of the wavelength, peak power, threshold current and slope efficiency during VCSEL operations.

High-performance 0.9- mu m-gate-length GaAs MESFETs on InP substrates and 1- mu m-gate-length GaAs-AlGaAs SDHTs on Si substrates are reported. The GaAs-on-InP MESFET structures exhibited extrinsic transconductances of 377 mS/mm at a gate bias of 0.6 V. The drain I-V characteristic showed excellent saturation, and the devices exhibited no light sensitivity of the DC characteristics. A unity current gain cutoff frequency of 22 GHz and a maximum frequency of oscillation of 30 GHz were measured. For the SDHTs on Si, the maximum transconductance was 220 mS/mm at 300 K and 364 mS/mm at 77 K. A minimum propagation delay of 28 ps/stage at room temperature was obtained for a 19-stage direct coupled FET logic ring oscillator with a power dissipation of 1.1 mW/stage. Microwave performance (f/sub T/=15 GHz, f/sub max/=22 GHz) comparable to that of homoepitaxial devices was obtained. >

A novel dry etch mixture based on HI/H/sub 2/ is shown to be a universal etchant for In-based semiconductors, giving rise to highly anisotropic features with smooth surface morphologies. At low DC self bias (-100 V) and low pressure (1 mTorr), etch rates for all III-V materials of >2000 AA-min/sup -1/ are possible for high HI percentages in the discharge, whereas rates >1 mu m-min/sup -1/ are obtained at higher pressures and DC biases. These etch rates are approximately an order of magnitude faster than for CH/sub 4//H/sub 2//Ar mixtures under the same conditions. Moreover, there is no polymer deposition on the mask or within the reactor chamber with HI/H/sub 2/. Auger electron spectroscopy reveals residue-free, stoichiometric surfaces after dry etching in this mixture. Results of etching with electron cyclotron resonance discharges of HBr/Ar, HBr/CH/sub 4/, and HBr/H/sub 2/ are also discussed. It is concluded that the HI/H/sub 2//Ar chemistry provides a strong alternative to CH/sub 4//H/sub 2//Ar, particularly for the etching of deep features. >

Carbon is an attractive p-type dopant for III-V semiconductors due to its thermal stability relative to Be or Zn. However, it has been shown to activate as an acceptor rather poorly in In/sub 0.53/Ga/sub 0.47/As due to the relative weakness of the In-C bond. One method for overcoming this problem is growth of short-period GaAs(C)/InAs superlattices in which carbon is introduced only in the GaAs and the InAs is left nominally undoped. Using this approach, the authors have achieved hole concentrations up to 7*10/sup 19/ cm/sup -3/ with hole mobilities of 20 cm/sup 2/-V/sup -1/ sec/sup -1/. Such structures are stable against rapid thermal annealing (10 s) up to 750 degrees C. The surface morphologies are specular even for very thick (0.95 mu m) layers, and remain so even after annealing at 750 degrees C. Because of the high carrier concentration and good thermal stability, these structures show great promise for applications to InP-based lasers and heterojunction bipolar transistors. >

We describe a new InGaP/lnGaAs/GaAs quantum well laser structure, the SPIN (Spread INdex) laser design. The figure of merit for the 980 nm Er-doped fiber application is how much power is coupled into the single-mode fiber. This is determined by the beam divergence and external differential quantum efficiency. To this end, the SPIN laser design allows a nearly symmetrical beam divergence, while maintaining high external differential quantum efficiency. The laser structure was grown by low pressure (45 Torr) metalorganic chemical vapor deposition (MOCVD).

The laser structure shown is of the ridge waveguide type. The epitaxial layers are grown over a (100) oriented GaAs substrate using MOCVD growth technique. These layers are 1.8 /spl mu/m thick n-InGaP cladding layer, the active region consisting of 80 A wide single InGaAs well bounded by 1000 A thick GaAs cladding layers, 1000 A InGaP layer, 70 A GaAs etch stop layer, p-InGaP cladding layer and p-GaAs contact layer. The etch stop layer may be positioned with respect to the active layer to give precise control ofthe lateral mode properties.

The use of implantation for doping and isolation of a variety of electronic and photonic III–V compound semiconductor devices will be reviewed. Complex multilayer heterostructure devices like heterojunction bipolar transistors and strained InGaAs-GaAs quantum well lasers rely on keV or MeV isolation implants, requiring thick, easily removed masks and post-implant annealing treatments to achieve high isolation resistances (≥ 108 Ω cm). The effectiveness of the implant isolation technique varies as a function of the bandgap and elemental composition of the semiconductor. Devices based on GaAs, AlxGa1-xAs and InGaP are particularly suited to the implant isolation method. The prime dopant species for III–V materials are Si for n-type layers and Be for p-type layers, although there is increasing interest in the use of C as an acceptor because of its low diffusivity. In the latter case, a group III species must be co-implanted with the C+ ion to enhance the occupation of the group V lattice site.

Through-wafer vias fabricated in InP substrates using high-rate (>or=1 mu m min/sup -1/) dry etching in an electron cyclotron resonance (ECR) Cl/sub 2//CH/sub 4//H/sub 2//Ar discharge at 150 degrees C are reported. The low process pressure ( approximately 2 mtorr) enables creation of small diameter (30 mu m) vias using photoresist masks and the anisotropic profiles are suitable for Au plating to complete the electrical front-to-back connection.

24 ps optical pulses of peak power in excess of 1.3 watts are continuously generated at GHz repetition rates using a GaAs/AlGaAs single quantum well broad area laser with an intracavity loss modulator. Efficient high power light modulation is also demonstrated with the same structure.

By cooling substrates to low temperatures (–40 °C), plasma etching of AlGaAs/AlAs/GaAs structures is performed in an ion-activated, surface reaction limited regime. As a result, microscopic and macroscopic uniformity are vastly improved and etching is independent of gas flow patterns, plasma geometry, and reactor loading. Because the reactant is concentrated on the surface, etching rates remain large.

High-quality GaAs-AlGaAs heterojunction bipolar transistors (HBTs) in which the carbon-doped base layers (p=10/sup 10/-10/sup 20/ cm/sup -3/, 400-800 AA thick) and Sn-doped collector and subcollector layers are grown by metalorganic molecular-beam epitaxy (MOMBE) and a subsequent regrowth using metalorganic chemical vapor deposition (MOCVD) is used to provide the n/sup +/ AlGaAs emitter and GaAs/InGaAs contact layers are discussed. A current gain of 20 was obtained for a base doping of 10/sup 19/ cm/sup -3/ (800 AA thick) in a 90- mu m-diameter device, with ideality factors of 1.0 and 1.4 for the base-collector and emitter-base junctions, respectively, demonstrating the excellent regrowth-interface quality. For a base doping of 10/sup 20/ cm/sup -3/ (400 AA thick), the current gain decreased to 8. >

We describe the design and performance of VCSEL's which have low thresholds and high quantum efficiency for practicality, are made with only photolithographically defined features for reproducibility, and easily integrate with electronic circuitry for usefulness.

Electron Cyclotron Resonance (ECR) plasma etching with additional if-biasing produces etch rates ≥ 2,500Å/min for InGaP and AlInP in CH4/H2/Ar. These rates are an order of magnitude or much higher than for reactive ion etching conditions (RIE) carried out in the same reactor. N2 addition to CH4/H2/Ar can enhance the InGaP etch rates at low flow rates, while at higher concentrations it provides an etch-stop reaction. The InGaP and AtlnP etched under ECR conditions have somewhat rougher morphologies and different stoichiometries up to ˜200Å from the surface relative to the RIE samples.