摘要:

Liquid‐helium temperature transport and magnetotransport measurements onn‐CdTe grown by molecular beam epitaxy onp‐InSb substrates have demonstrated the presence of a quasi‐two‐dimensional electron gas in the InSb at the InSb/CdTe interface. The electron density and mobility in the channel can be varied by back gating.

ISSN:0003-6951    

DOI:10.1063/1.97409

出版商:AIP    

年代:1986

数据来源: AIP

摘要:

Convergent beam electron diffraction using either the (200) systematic row and/or the (011) zone axis was successfully applied to determine the crystal polarity in (011) GaAs samples. This method makes it possible to distinguish the stacking sequence of the As and Ga planes. The information existing in the 200 disk of the diffraction pattern is different, depending on whether a particular disk refers to the As or the Ga plane. Therefore, this method can be generally applied in transmission electron microscopy forinsitusamples and without any chemical etching.

ISSN:0003-6951    

DOI:10.1063/1.97410

出版商:AIP    

年代:1986

数据来源: AIP

摘要:

Photoluminescence (PL) decay time measurements at 77 and 300 K are reported from 6.1 nm GaAs single quantum well heterostructures (SQWH’s) confined by GaAs/AlAs short‐period superlattices (SPS’s) or ternary AlGaAs alloys with similar Al content, prepared by molecular beam epitaxy. The SQW PL intensity exhibits a single exponential decay with a time constant of 1.6 ns for SQWH’s confined by SPS’s and 0.3 ns for SQWH’s confined by AlGaAs alloys at 77 K. From comparison of the decay rates in both types of the sample, it is found that the radiative recombination efficiency is improved by a factor of about 6 in SPS confined SQWH’s. This higher efficiency is attributed to the improved heterointerfaces in addition to the enhanced radiative recombination rate due to the increased overlap of electron and hole wave functions in the narrow SQW.

ISSN:0003-6951    

DOI:10.1063/1.97411

出版商:AIP    

年代:1986

数据来源: AIP

摘要:

We report the first measurement of the third‐order nonlinear susceptibility &khgr;(3)in layered semiconductor clusters exhibiting pronounced quantum size effects at room temperature. BiI3clusters prepared in colloidal form in acetonitrile had a thickness of &bartil;7 A˚ and lateral dimensions between 60 and 90 A˚. Using degenerate four‐wave mixing, we observed that the conjugate pulses from the small and the large gratings had comparable intensities, verifying the electronic origin of the nonlinearity. The nonlinear susceptibility was found to be 2.3×10−11esu for a colloid with a cluster volume fraction of 10−5.

ISSN:0003-6951    

DOI:10.1063/1.97412

出版商:AIP    

年代:1986

数据来源: AIP

摘要:

Extremely thin InAs/GaAs single quantum well structures have been grown by atomic layer epitaxy. The wells were 2 and 4 InAs monolayers thick. Photoluminescence spectra (19 K) from these structures are sharp, intense, and uniform across the sample with full widths at half‐maximum for the 2 and 4 monolayer wells of 12 and 17 meV, respectively. These results indicate the high degree of control inherent in atomic layer epitaxy as well as its ability to grow high quality materials.

ISSN:0003-6951    

DOI:10.1063/1.97413

出版商:AIP    

年代:1986

数据来源: AIP

摘要:

The behavior of oxidation‐induced stacking faults (OSF’s) during the O2/NF3oxidation of silicon has been investigated in the temperature range of 850–1100 °C. A very fast shrinkage rate of pregrown OSF in silicon and a nonlinear shrinkage rate with time have been observed. The shrinkage rate of OSF decreases as the oxidation time is increased. It is proposed that the fast OSF shrinkage is due to excessive vacancy flux as a result of the reaction of fluorine at the Si/SiO2interface during the initial transient state, and subsequently the shrinkage rate is reduced as the steady‐state condition of vacancy‐interstitial recombination is approached. It has also been found that no OSF’s are generated even when mechanical damage by abrasion is done prior to oxidation.

ISSN:0003-6951    

DOI:10.1063/1.97414

出版商:AIP    

年代:1986

数据来源: AIP

摘要:

This letter describes the results ofinsituobservations of dislocation behavior in In‐doped GaAs crystals at high temperatures using synchrotron radiation topography and high‐temperature stressing apparatus. The generation and propagation processes of dislocations in a preyield stage have been investigated by making a comparison with undoped crystals. We find that there is a one‐directional predominance in the generation and propagation of dislocations in In‐doped crystals.

ISSN:0003-6951    

DOI:10.1063/1.97415

出版商:AIP    

年代:1986

数据来源: AIP

摘要:

The effect of substrate temperature (Ts) on the initial nucleation of hydrogenated amorphous silicon (a‐Si:H) prepared by glow discharge has been studied using aninsituellipsometry probe. Evidence in the ellipsometry data for clustering of Si–Si bonds at nucleation centers, for films prepared withTs∼250 °C, gradually disappears asTsis reduced below ∼200 °C. This indicates that the clustering process accompanies defect reduction during growth commonly observed in glow dischargea‐Si:H asTsis increased. ForTs>200 °C, a sufficiently high surface mobility may enable the depositing species to bind at lower energy sites, thus explaining the observed results.

ISSN:0003-6951    

DOI:10.1063/1.97416

出版商:AIP    

年代:1986

数据来源: AIP

摘要:

The first solid‐state field‐effect transistor has been fabricated utilizing a film of an organic macromolecule, polythiophene, as a semiconductor. The device characteristics have been optimized by controlling the doping levels of the polymer. The device is a normally off type and the source (drain) current can be modulated by a factor of 102–103by varying the gate voltage. The carrier mobility and the transconductance have also been determined to be ∼10−5cm2/V s and 3 nS, respectively, by means of electrical measurements.

ISSN:0003-6951    

DOI:10.1063/1.97417

出版商:AIP    

年代:1986

数据来源: AIP

摘要:

Gold micropatterns have been generated by the laser photolysis of dimethylgold (III) acetylacetonate, Me2Au(acac), in the vapor phase. Linewidths as fine as 2 &mgr;m were readily obtained utilizing a simple optical projection system comprised of a 4× projection lens, a lithographic photomask, and the UV output from an excimer laser. The single‐step, dry process for selectively producing metal patterns is highlighted.

ISSN:0003-6951    

DOI:10.1063/1.97418

出版商:AIP    

年代:1986

数据来源: AIP