摘要:

InAs/GaAs highly strained short‐period superlattices have been grown by migration‐enhanced epitaxy on InP(001) substrates. Such samples exhibit clearly improved structural and optical properties. X‐ray diffraction, scanning transmission electron microscopy, photoluminescence, and Raman scattering experiments have been performed to characterize an (InAs)4(GaAs)3layer.

ISSN:0003-6951    

DOI:10.1063/1.101435

出版商:AIP    

年代:1989

数据来源: AIP

摘要:

Al content dependence of GaAs/AlxGa1−xAs superlattice ionization rates was studied. The electron ionization rate is enhanced when the AlGaAs of the barrier is a direct transition type. It is drastically reduced at the &Ggr;‐Xband crossover in the AlGaAs layer. The ionization rate ratio (hole to electron) as determined by excess multiplication noise measurement is reduced from a value of 0.5 atx=0.3 to 0.14 atx=0.45. At higher values ofx, corresponding to the onset of indirect electron transitions, the noise is increased.

ISSN:0003-6951    

DOI:10.1063/1.100825

出版商:AIP    

年代:1989

数据来源: AIP

摘要:

Low‐field mobility of two‐dimensional electron gas (2DEG) in selectively doped pseudomorphicN‐Al0.3Ga0.7As/ Ga0.8In0.13As/GaAs structures was measured as a function of carrier concentration as well as a function of temperature. In order to explain the observed mobility characteristics, scattering due to clustering has been considered. It is shown that the low‐field mobility of 2DEG at low temperature (<40 K) can be explained by the scattering due to clustering together with the remote ionized impurity scattering.

ISSN:0003-6951    

DOI:10.1063/1.100826

出版商:AIP    

年代:1989

数据来源: AIP

摘要:

AlGaAs/GaAs heterojunction bipolar transistors are fabricated using carbon‐dopedp‐type GaAs base regions grown for the first time by flow‐rate modulation epitaxy. Because of the much smaller diffusion coefficient of carbon atoms in GaAs than that of beryllium and otherp‐type impurities, sharp impurity profiles are achieved. The heterojunction bipolar transistors exhibited high current gains up to 40 for a base layer width of 150 nm and base doping of 2.4×1019cm−3. The electron lifetime in heavily carbon‐doped GaAs layers is considerably long, indicating favorable quality of heavily carbon‐doped layers.

ISSN:0003-6951    

DOI:10.1063/1.100827

出版商:AIP    

年代:1989

数据来源: AIP

摘要:

Strained‐layer structures consisting of ∼30–35 nm Si1−xGex(x=0.16–0.29) and 33 nm Si deposited by molecular beam epitaxy on a (100)Si substrate have been amorphized by ion implantation at 40 K with 120 keV As+. Rutherford backscattering/channeling measurements using 2 MeV He+ions have been used to measure the thickness of the amorphous layer and monitor the subsequent epitaxial regrowth occurring as a result of annealing at 560–600 °C. Angular scans across the {110} planar channels indicate that the initial crystallinity and strain was recovered forx=0.16; however, forx=0.29 crystal quality was greatly reduced and the coherency at the substrate‐alloy layer interface was destroyed.

ISSN:0003-6951    

DOI:10.1063/1.100828

出版商:AIP    

年代:1989

数据来源: AIP

摘要:

Photoluminescence properties of as‐grown and post‐growth annealed GaAs directly grown on Si substrates by metalorganic vapor phase epitaxy are studied at various temperatures. At low temperature, three extrinsic lines and an intrinsic exciton line split by residual biaxial tensile stress are observed. The extrinsic lines give evidence of growth‐induced defects. One of these lines, involving the presence of Si acceptors, appears after post‐growth annealing (10 min at 800 °C). The biaxial stress deduced from the intrinsic lines varies with temperature; extrapolation to zero stress results in a temperature slightly below the growth temperature.

ISSN:0003-6951    

DOI:10.1063/1.100829

出版商:AIP    

年代:1989

数据来源: AIP

摘要:

We have studied strained InGaAs quantum wells with GaAlAs barriers, grown by molecular beam epitaxy, varying In content and well thickness. Photoluminescence measurements were made at 12 K. The appearance of a characteristic additional exciton‐like photoluminescence peak indicates the transition between elastically strained and relaxed layers. This transition was also observed by the occurrence of misfit dislocations in the corresponding transmission electron microsope (TEM) images. Layer thicknesses and In content were also determined by TEM. The results give a critical layer thickness of 29±0.5 nm at an In content of 32±2%. This value lies about a factor of 3–4 above the critical layer thickness calculated by Matthews and Blakeslee [J. Cryst. Growth27, 118 (1974)].

ISSN:0003-6951    

DOI:10.1063/1.100830

出版商:AIP    

年代:1989

数据来源: AIP

摘要:

GaAs‐based field‐effect transistor structures have been grown on InP substrates with the InGaAs/GaAs strained‐layer superlattices and 1.5 &mgr;m GaAs layer as the buffer. The low‐temperature (4 K) photoluminescence (PL) from this GaAs buffer has been studied for the first time. Among five observable peaks, the excitonic transition at energy 1.513 eV and the impurity associated recombination at energy 1.483 eV have been identified with the aid of reflection, absorption, and temperature and excitation‐intensity dependent PL measurements. The peak at 1.504 eV, most probably due to an exciton bound to a defect, is greatly enhanced compared with that of homoepitaxially grown GaAs. The optical results show that GaAs films of good quality can be grown on InP substrate, which is consistent with device results.

ISSN:0003-6951    

DOI:10.1063/1.100832

出版商:AIP    

年代:1989

数据来源: AIP

摘要:

A laser‐assisted photochemically driven etching process has been developed for Hg0.8Cd0.2Te (12 &mgr;m material). It is an etch which does not melt the surface of the material or induce mercury migration. Small geometry features (vias less than 10 &mgr;m in diameter) with straight‐edged sidewalls have been produced. The etching mechanism is a photoenhanced rapid oxidation with subsequent solvation of the oxides.

ISSN:0003-6951    

DOI:10.1063/1.100833

出版商:AIP    

年代:1989

数据来源: AIP

摘要:

We have generated electrical pulses of only 480 fs duration by photoconductive switching in CdTe grown by ultraviolet‐enhanced metalorganic chemical vapor deposition (MOCVD). In addition to the extremely fast switching times, MOCVD CdTe also exhibits a high mobility of 180 cm2/V s and can be grown on almost any substrate, making it ideal for integration into existing circuits and devices.

ISSN:0003-6951    

DOI:10.1063/1.100834

出版商:AIP    

年代:1989

数据来源: AIP