摘要:

A novel approach for constructing the band diagrams of semiconductor heterojunctions is discussed and illustrated. It is based on a simple measurement of band discontinuities, Debye length and the width of the space–charge region at the heterojunction interface. Monitoring the changes in the surface potential during heterojunction formation makes it possible to identify the contributions of the interface states and dipole. The approach is illustrated by the results of experiments performed on the InP/In2O3heterojunction. ©1995 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.114055

出版商:AIP    

年代:1995

数据来源: AIP

摘要:

Photoconductive properties of diamond optical switch made by chemical vapor deposition method were investigated. A new configuration of the diamond gap was proposed to reduce the surface leakage current and avoid surface flashover. This technology made it possible to apply static high electric field up to 2×106V/cm. The dependence of the mobility‐lifetime product (&mgr;&tgr;) on the grain size was measured for a wide range of electric field. The &mgr;&tgr; value was increased to be linearly proportional to the electric field for every grain size sample, and no saturation was measured even at a high electric field ofE=3×105V/cm. Larger grain size samples had larger &mgr;&tgr; values. The grain size dependence was attributed to the decreasing of the mobility or the lifetime inside the grain not due to the increasing recombination ratio at the grain boundary in smaller grain size samples. ©1995 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.114056

出版商:AIP    

年代:1995

数据来源: AIP

摘要:

Atomic force microscopy is employed to obtain images of the surface of GaSb epilayers grown on (001) GaAs using molecular beam epitaxy. The images reveal a surface that consists of micron size mounds that are approximately 4 nm high. A stepped surface is clearly observed on the mounds with a single step edge that originates from a screw dislocation at the center of the mound and moves out to the edge in a spiral fashion. The surface structure of the spiral mounds is observed to depend on the growth temperature of the GaSb epilayer, presumably as a result of a shorter diffusion length of the group III adatoms for lower substrate temperatures. ©1995 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.114057

出版商:AIP    

年代:1995

数据来源: AIP

摘要:

The optical gains in AlGaInP/GaInP strained quantum wells using valence band structures by the second‐orderk⋅pmethod, with and without spin‐orbit split‐off (SO) band effect have been calculated. It was easy to overestimate the optical gain without considering the SO‐band effect, because a small spin‐orbit splitting energy for GaInP makes higher nonparabolicity of the valence bands. The SO‐band effect is particularly significant under tensile strain, since the SO band makes the effective mass very large due to the large interaction between the SO and light hole bands. ©1995 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.114058

出版商:AIP    

年代:1995

数据来源: AIP

摘要:

We report in this letter the observation of visible photoluminescence (PL) at room temperature from hydrogenated nanocrystalline silicon (nc‐Si:H)/amorphous silicon (a‐Si:H) multilayers (MLs) prepared in a plasma enhanced chemical vapor deposition system without any postprocessing. The PL peak wavelength can be controlled, blueshifting from 750 to 708 nm, through reducing the width of thenc‐Si:H sublayers from 4.0 to 2.1 nm. Quantum size effect innc‐Si:H sublayers of the ML is responsible for the emission above the band gap of bulk crystal Si. ©1995 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.114059

出版商:AIP    

年代:1995

数据来源: AIP

摘要:

We report here the characteristic features of a newly developed dielectric encapsulant cap layer, which after adequate thermal treatments, leads to a reproducible local alloy disorder in several III–V quantum well (QW) structures. Data are presented to demonstrate its universality, namely, its ability to promote alloy‐disorder free of charge carriers either on group III or group V sublattice depending on the type of the QW structure. ©1995 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.114060

出版商:AIP    

年代:1995

数据来源: AIP

摘要:

The surface quality of &bgr;SiC films grown on Si(100) by chemical vapor deposition has been assessed through synchrotron photoemission measurements of the valence band and of the linewidths and surface‐induced structure in Si 2pcore‐level spectra. For thesen‐type samples, band bending is small on thec(2×2) and (3×2) surfaces but larger on the (2×1), which also exhibits an increased Si 2plinewidth and evidence of elemental Si patches. All three reconstructions show emission from gap states extending from the valence band maximum to the Fermi level.

ISSN:0003-6951    

DOI:10.1063/1.114061

出版商:AIP    

年代:1995

数据来源: AIP

摘要:

We report studies of GaAs/AlAs short period superlattices using cross‐sectional scanning tunneling microscopy. In particular, we investigate the role of growth interrupt time on the resulting interfacial structure. Superlattices with repeated periods of four layers of GaAs and two layers of AlAs are resolved atom by atom. Superlattices grown using a 30 s growth interrupt time are observed while those grown with a 5 s growth interrupt time are not. We also discuss residual effects of the growth interrupt process on layers grown on top of the short‐period superlattice. ©1995 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.114062

出版商:AIP    

年代:1995

数据来源: AIP

摘要:

InSb enhancement‐mode, metal‐insulator‐semiconductor, field‐effect transistors with 1 &mgr;m gate lengths have been fabricated. When operated at room temperature with less than 0.5 V applied between the source and drain, the transistors have a static dynamic range in excess of 20 dB, a cut‐off frequency (fT) of 14 GHz and a transconductance, at 1 GHz, of 230 mS mm−1. Analysis of the parasitic capacitances indicates an intrinsicfTof about 90 GHz. The static electron mobility in the channel is 2×104cm2 V−1 s−1, so a carrier velocity of about 3.7×107cm s−1should be attained. This leads to a predicted frequency response of 84 GHz, in reasonable agreement with the intrinsic microwave data.

ISSN:0003-6951    

DOI:10.1063/1.114063

出版商:AIP    

年代:1995

数据来源: AIP

摘要:

Cooling (Pb,La)(Zr,Ti)O3films from their pulsed laser deposition temperature in a reducing ambient yields a voltage offset in the polarization–voltage characteristics. Reversing the as‐processed polarization at 120 °C nearly removes the offset. By reversing the polarization at room temperature and either heating the film at zero voltage or illuminating the film with UV light, the offset can be partially changed. All changes are recoverable using the same processes with opposite polarity polarization. This behavior is explained by a process‐induced accumulation of oxygen vacancies at one interface, oxygen vacancy defect‐dipole complexes throughout the film, and trapping of free electrons at the interface of positive polarization. Voltage offset and shift effects are not observed in films cooled in 1 atm of oxygen ©1995 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.114064

出版商:AIP    

年代:1995

数据来源: AIP