摘要:

A novel technique for the passivation of high power SiCp‐ndiodes using porous SiC is demonstrated. An increase from around 250 to 600 V in the reverse breakdown voltage is observed following the passivation treatment. The breakdown mode is also reversible in the passivated case in contrast to the permanent degradation in the nontreated device. ©1995 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.113668

出版商:AIP    

年代:1995

数据来源: AIP

摘要:

Degenerately doped (n=5×1020cm−3) InN grown by metalorganic molecular beam epitaxy is used for emitter Ohmic contacts on GaAs/AlGaAs heterojunction bipolar transistors (HBTs). Both abrupt InN/GaAs and graded GaAs/InGaAs/InN contact structures were investigated. Although, the contact resistivity of nonalloyed Ti/Pt/Au on InN was achieved as low as 1.8×10−7&OHgr; cm2, formation of a thin GaN layer at the interface of the InN/GaAs system limits nonalloyed TiPtAu metallization to contact resistivities of 10−4&OHgr; cm2. Whereas the graded structure, GaAs/InGaAs/InN material, system produces values of 5×10−7&OHgr; cm2which resulted in the formation of conductive InN from nitridation of InAs instead of the GaN layer for the InN/GaAs system. The InN‐based emitter contacts have superior surface morphologies to the more conventional InAs layers. The C‐doped base (p=7×1019cm−3) HBTs utilizing 2×5 &mgr;m2InN‐based emitter contacts is demonstrated with dc gains of 35. ©1995 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.113669

出版商:AIP    

年代:1995

数据来源: AIP

摘要:

Flow rate modulation epitaxy (FME) is applied to the low‐temperature growth of AlGaAs/GaAs quantum wires (QWRs) on nonplanar substrates. The growth selectivity is found to be enhanced greatly by the use of FME, as compared with the conventional metalorganic chemical vapor deposition due to the enhanced migration of Ga species. An AlGaAs/GaAs QWR with a central thickness of about 9 nm and a lateral width of about 28 nm is grown at 600 °C on a V‐grooved substrate. Good photoluminescence properties are observed from the grown QWR, with the peak energy being in good agreement with the calculated energy level of a parabolic shape lateral confinement potential. ©1995 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.113670

出版商:AIP    

年代:1995

数据来源: AIP

摘要:

We report on the growth of GaN with a zinc‐blende, wurtzite, or a mixed phase structure on (001)GaP and (001)GaAs substrates by a low‐temperature modified molecular beam epitaxy technique. By systematically varying the incident arsenic overpressure, films grown at a moderate substrate temperature of ≊620 °C show predominately wurtzite &agr;‐GaN, zinc‐blende &bgr;‐GaN, or a mixed phase of the two. Films containing only the metastable phase &bgr;‐GaN were achieved by using a relatively high growth temperature of ≊700 °C and with an arsenic overpressure of ≊2.4×10−5Torr. X‐ray diffraction measurements indicate an improved crystalline quality for the layers grown at ≊700 °C compared to those grown at ≊620 °C as evident by a narrower full width at half‐maximum of 35 min for &bgr;‐GaN, which is among the narrowest reported to date. ©1995 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.113671

出版商:AIP    

年代:1995

数据来源: AIP

摘要:

The normal incidence absorption between 2 and 14 &mgr;m in a pseudomorphicp‐Si0.81Ge0.19/Si multiple quantum well sample with doping 5×1012cm−2per well is described by a Drude conductivity characteristic of free carriers, with an in‐plane mobility of 32 cm2/V s and a relaxation time of 5.5 fs at 77 K. When the absorption is scaled with dopant concentration these parameters predict quantum efficiencies for quantum well infrared photodetectors in reasonable agreement with experiment.

ISSN:0003-6951    

DOI:10.1063/1.113630

出版商:AIP    

年代:1995

数据来源: AIP

摘要:

We have created atomic scale modifications on the GaAs(111)B surface by applying voltage pulses between the tip of a scanning tunneling microscope and a GaAs sample under ultrahigh vacuum conditions. A voltage pulse of 5 V (sample negative) for 25 ms results in the creation of a disordered region (approximately, 3 nm×3 nm in area) of As trimers. In addition, surface stacking faults are formed which extend over distances of order 10 nm and terminate on surface defects. A pulse with the same parameters, but opposite polarity, creates a nanometer scale crater. We argue that the smallest features are formed by electric field induced diffusion (for negative bias pulses) or field desorption (positive bias pulses). ©1995 American Institute of Physics. 

ISSN:0003-6951    

DOI:10.1063/1.113631

出版商:AIP    

年代:1995

数据来源: AIP

摘要:

In this letter we have investigated then‐type doping properties of Zn1−xMgxSe grown by molecular beam epitaxy using a solid ZnCl2source as dopant. We describe the effect of dopant source temperature on the carrier concentration and show that the optimum doping temperature changes with varying Mg compositions. At the same time, the highest achievable electron concentration decreases as the Mg content in the sample increases, and this behavior can be described by a model that assumes that the Fermi level is pinned 120 meV above the conduction band edge of ZnSe, in an absolute energy scale. ©1995 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.113632

出版商:AIP    

年代:1995

数据来源: AIP

摘要:

We report on electrically detected magnetic resonance (EDMR) studies in siliconpndiodes in the temperature range from 30 to 300 K. In the range from 150 to 300 K the resonance effect is, as usually observed, much larger than expected by spin polarization. From 150 K down to 30 K the spin resonance effect increases by a factor of 25, which is attributed to spin polarization of free electrons and electrons bound to recombination centers. Our investigation suggests that at least two different mechanisms contribute to the EDMR signal. ©1995 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.113633

出版商:AIP    

年代:1995

数据来源: AIP

摘要:

A high performance metal‐insulator‐semiconductor–like pseudomorphic field‐effect transistor utilizing ann−‐GaAs/n+‐In0.2Ga0.8As two‐layer structure was fabricated and demonstrated. Then−‐GaAs layer is used as the Schottky contact layer whereas then+‐In0.2Ga0.8As quantum well is employed as the active channel. Due to the excellent properties of the InGaAs layer and carrier confinement effect at the In0.2Ga0.8As–GaAs heterointerface, the device under study shows the advantages of high breakdown voltage, high current capability, very large gate voltage swing for high transconductance operation, and ease of fabrication. For a 2×100 &mgr;m2gate device, a breakdown voltage of 17.4 V, a maximum drain saturation current of 930 mA/mm, a maximum extrinsic transconductance of 230 mS/mm, and a very wide gate voltage range larger than 3 V with the extrinsic transconductance higher than 200 mS/mm are obtained. Therefore, the device has great potential for use in high speed, high power, and large input signal circuit applications. ©1995 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.113634

出版商:AIP    

年代:1995

数据来源: AIP

摘要:

A hydrogen‐terminated silicon surface was successfully converted to a surface covered with a monolayer of nitrogen. Nitridation was carried out in a vacuum chamber using either dimethylhydrazine [H2N–N(CH3)2] or ammonia at a pressure of 1 mTorr and at temperatures ranging from 400 to 600 °C.Insitux‐ray photoelectron spectroscopy measurements revealed that the binding energy and the full width at half‐maximum in the nitrogen spectra are the same as those in bulk Si3N4. Nitrogen content at the surface increased as the nitridation time increased and, below 500 °C, saturated at a value that approximately corresponds to a monolayer thickness. These results show the effectiveness of dry chemical processes for preparing uniform Si surfaces terminated with specific atoms or molecules other than hydrogen. ©1995 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.113635

出版商:AIP    

年代:1995

数据来源: AIP