AlAs oxidation process in GaAs/AlGaAs/AlAs heterostructures grown by molecular beam epitaxy on GaAs (n11)A substrates

The lateral oxidation of AlAs layers grown on GaAs (100), (110) and (n11)A-oriented substrates (n=1, 2, 3, 4) was studied. The temperature dependence of the oxidation rate was measured between 390°C and 450°C. The oxidation rate is highly anisotropic and the anisotropy is related to the symmetry of the crystal structure. The oxidation process has an activation energy that depends on substrate orientation. The oxidation front line becomes irregular for temperatures higher than 450°C and the surface of the samples was degraded when the temperature exceeded 540°C. The time dependence of the oxidation rate was found to be similar to the Si oxidation process.     

AlGaAs/InGaAs/GaAs strained-layer heterojunction bipolar transistors by molecular beam epitaxy

The growth and characteristics of the first AlGaAs/InGaAs/GaAs HBTs are reported. Layers with up to 10% indium content appeared to be free of misfit dislocations, and resulted in HBTs with good I/V characteristics which scaled with In content according to theory.     

Super-flat interfaces in In0.53Ga0.47As/In0.52Al0.48As quantum wells grown on (411)A InP substrates by molecular beam epitaxy

Effectively atomically flat interfaces over a macroscopic area (“(411)A super-flat interfaces”) were successfully achieved in In_0.53Ga_0.47As/In_0.52Al_0.48As quantum wells (QWs) grown on (411)A InP substrates by molecular beam epitaxy (MBE) at a substrate temperature of 570°C and V/III=6. Surface morphology of the In_0.53Ga_0.47As/In_0.52Al_0.48As QWs was smooth and featureless, while a rough surface of those simultaneously grown on a (100) InP substrate was observed. Photoluminescence (PL) linewidths at 4.2 K from the (411)A QWs with well width of 0.6–12 nm were 20–30 % narrower than those grown on a (100) InP substrate and also they are almost as narrow as each of split PL peaks for those of growth-interrupted QWs on a (100) InP substrate. In the case of the (411)A QWs, only one PL peak with very narrow linewidth was observed from each QW over a large distance (7 mm) on a wafer.     

Selective photochemical dry etching of GaAs/AlGaAs and InGaAs/InAlAs heterostructures

Selective photochemical dry etching of GaAs layers on AlGaAs using HCl gas and InGaAs layers on InAlAs using CH/sub 3/Br gas is studied. A low pressure mercury lamp was used as the deep UV light source. A selectivity of more than 150 for GaAs over AlGaAs and more than 60 for InGaAs over InAlAs was obtained.<>     

A high-gain GaAs/AlGaAs n-p-n heterojunction bipolar transistor on(100) Si grown by molecular beam epitaxy

High-gain GaAs/AlGaAs n-p-n heterojunction bipolar transistors (HBT's) on Si substrates grown by molecular beam epitaxy (MBE) have been fabricated and tested. In this structure, an n⁺-InAs emitter cap layer was grown in order to achieve a nonalloyed ohmic contact. Typical devices with an emitter dimension of 50×50 μm² exhibited a current gain as high as 45 at a collector current density of 2×10³ A/cm² with an ideality factor of 1.4. This is the highest current gain reported for HBT's grown on Si substrates. Breakdown voltages as high as 10 and 15 V were observed for the emitter-base and collector-base junctions respectively. The investigation on devices with varying emitter dimensions demonstrates that much higher current gains can be expected     

AlGaAs/GaAs JFETs by organo-metallic and molecular beam epitaxy

Normally-off and normally-on AlGaAs/GaAs heterojunction gate GaAs FETs (HJFETs) for high-speed logic applications have been fabricated with molecular beam epitaxy (MBE) and organometallic vapour phase epitaxy (OM-VPE). The best normally-off devices used MBE n-GaAs active layers and OM-VPE gate layers of p+-AlGaAs and p+-GaAs. Saturation currents followed a square law and current scaling constants were the highest on record for HJFETs, greater than 50 ?A/?m-V2.     

A planar-doped 2D-hole gas base AlGaAs/GaAs heterojunction bipolartransistor grown by molecular beam epitaxy

A novel type of AlGaAs/GaAs heterojunction bipolar transistor (HBT) which uses a two-dimensional (2-D) hole gas base formed by planar doping using molecular-beam epitaxy (MBE) has been demonstrated. The base consists of a submonolayer of Be atoms of sheet concentration 0.5-5×10¹³ cm^-2 which is deposited during growth interruption by MBE. The transistor structure exhibits DC current gains up to 700. The effective base transit time is negligible in these transistors and it is postulated that very high-speed nonequilibrium transport may occur in the collector region     

Hybrid AlGaAs/GaAs/AlGaAs nanowires with a quantum dot grown by molecular beam epitaxy on silicon

Data on the growth features and physical properties of GaAs inserts embedded in AlGaAs nanowires grown on Si(111) substrates by Au-assisted molecular beam epitaxy are presented. It is shown that by varying the growth parameters it is possible to form structures like quantum dots emitting in a wide wavelength range for both active and barrier regions. The technology proposed opens up new possibilities for the integration of direct-band III–V materials on silicon.     

Planar-doped n-type InAlAs/InGaAs MODFETs on InP(311)A substratesby molecular beam epitaxy

N-type doping of silicon in InAlAs/InGaAs/InP modulation-doped field effect transistor (MODFET) structures grown by molecular beam epitaxy (MBE) for the (311)A orientation has been achieved by using the planar-doping technique. An electron mobility as high as 50000 cm² V-s with a sheet carrier concentration of 1.9×10¹²/cm² at 77 K is reported. MODFETs with 1.2-μm gate length exhibit an extrinsic transconductance of 400 mS/mm and a maximum drain current of 485 mA/mm. The results are comparable to those of MODFETs grown on (100) InP substrates. The results point to the possibility of making p-n multi layer structures with all-silicon doping     

High-performance long-wavelength InGaAs=GaAs multiple quantum-well lasers grown by molecular beam epitaxy

High-quality 1.2 mum InGaAs/GaAs single and triple quantum-well lasers grown by molecular beam epitaxy are demonstrated. For the triple quantum well, a record low threshold current density of 107 A/cm² /well is achieved for a 100 times1000 mum laser     

Study of metamorphic InGaAs/GaAs quantum well laser materials grown on GaAs substrate by molecular beam epitaxy

The GaAs based InGaAs metamorphic structures and their growth by molecular beam epitaxy (MBE) are investigated. The controlling of the source temperature is improved to realize the linearly graded InGaAs metamorphic structure precisely. The threading dislocations are reduced. We also optimize the growth and annealing parameters of the InGaAs quantum well (QW). The 1.3-μm GaAs based metamorphic InGaAs QW is completed. A 1.3-μm GaAs based metamorphic laser is reported.     

Inner-stripe AlGaAs/GaAs laser diode by single-step molecular beam epitaxy

A novel fabrication technique for a real refractive-index-guide inner-stripe laser by a single-step crystal growth is reported. The injected current is confined in the p-type silicon-doped GaAs region on the V-shaped groove with (111)A slopes by the crystal-orientation-dependent amphoteric nature of the silicon impurity in GaAs.     

Vertically compact 15 GHz GaAs/AlGaAs multiple quantum well laser grown by molecular beam epitaxy

A GaAs/Al/sub x/Ga/sub 1-x/As multiple quantum well laser with an electrical modulation bandwidth exceeding 15 GHz has been fabricated. Optimised design of the waveguide, including development of high Al mole fraction (x=0.8) cladding layers, together with a coplanar electrode geometry, has resulted in a vertically compact laser structure suitable for integration.<>     

AlGaAs/Ge/GaAs heterojunction bipolar transistors grown bymolecular beam epitaxy

An N-Al_0.22Ga_0.78As emitter, p-Ge base, and n-GaAs collector (AlGaAs/Ge/GaAs) heterojunction bipolar transistor (HBT) in the emitter-up configuration grown by molecular beam epitaxy is discussed. Devices exhibited common-emitter current gains of as high as 300 at a collector current density of 2000 A/cm² and a collector voltage of 4 V. As the device area is reduced from 50×50 to 10×40 μm, the current gain did not show significant changes, suggesting a low surface recombination velocity in the Ge base     

Double-heterostructure AlGaAs/GaAs lasers grown on the mesas of trenched Si substrate by molecular beam epitaxy

The growth and device characteristics of stripe Al/sub 0.26/Ga/sub 0.74/As/GaAs double-heterostructure lasers grown on mesas of trenched Si by MBE is reported. The TE and TM modes lase at different injection levels depending on the laser stripe width. This behaviour is attributed to the variation of the residual thermal stress present in the laser structures as a function of stripe width. By comparing the polarisations of the laser radiations from a narrow and broad stripe laser, it is found that a narrow mesa is effective in reducing the residual thermal stress.<>     

InGaAs/lnP heterojunction bipolar transistor grown by all-solidsource molecular beam epitaxy

State-of-the-art InGaAs/InP heterojunction bipolar transistors were grown by all-solid source molecular beam epitaxy. Fabricated transistors showed cutoff frequencies of >100 GHz with an emitter area of 1.5×5 μm². Together with recent studies. These results demonstrate that the valved cracker technique is a very competitive nontoxic growth method     

Investigation of high In content InGaAs quantum wells grown on GaAs by molecular beam epitaxy

Excitonic resonances and the quantum confined Stark effect are observed near 1.3 mu m in InGaAs quantum wells grown on GaAs using a slowly graded InGaAs buffer. The pin structure performs as a modulator with a relative transmission modulation of 12% at 1.3 mu m and as a low leakage photodetector.<>     

Very low threshold current densities (under 100 A/cm2) in AlGaAs/GaAs single-quantum-well GRINSCH lasers grown by molecular beam epitaxy

Threshold current densities as low as 80 A/cm2 for 3.3 mm-long cavity lasers, and 93 A/cm2 for 520 ?m-long cavity lasers have been obtained in AlGaAs/GaAs graded-index separate-confinement heterostructure (GRINSCH) single-quantum-well lasers with quantum-well widths between 65?165 A grown by molecular beam epitaxy. The structures were prepared on (100) GaAs substrates and do not display the earlier reported dependence of lasing threshold characteristics on the quantum-well thickness in the range studied (65?165 A).     

分子束外延生长的GaAs/GaInP双结电池研究

We report the recent result of GaAs/GaInP dual-junction solar cells grown by all solid-state molecularbeamepitaxy(MBE).The device structure consists of a GaIn0.48P homojunction grown epitaxially upon a GaAs homojunction,with an interconnected GaAs tunnel junction.A photovoltaic conversion efficiency of 27% under the AM1.5 globe light intensity is realized for a GaAs/GaInP dual-junction solar cell,while the efficiencies of 26% and 16.6% are reached for a GaAs bottom cell and a GaInP top cell,respectively.The energy loss mechanism of our GaAs/GaInP tandem dual-junction solar cells is discussed.It is demonstrated that the MBE-grown phosphide-containing Ⅲ–V compound semiconductor solar cell is very promising for achieving high energy conversion efficiency.     

A GaAs/GalnP dual junction solar cell grown by molecular beam epitaxy

We report the recent result of GaAs/GalnP dual-junction solar cells grown by all solid-state molecularbeam-epitaxy （MBE）. The device structure consists of a GaIn0.4sP homojunction grown epitaxially upon a GaAs homojunction, with an interconnected GaAs tunnel junction. A photovoltaic conversion efficiency of 27% under the AM1.5 globe light intensity is realized for a GaAs/GaInP dual-junction solar cell, while the efficiencies of 26% and 16.6% are reached for a GaAs bottom cell and a GaInP top cell, respectively. The energy loss mechanism of our GaAs/GalnP tandem dual-junction solar cells is discussed. It is demonstrated that the MBE-grown phosphide-containing Ⅲ-V compound semiconductor solar cell is very promising for achieving high energy conversion efficiency.