Compositional dependence of Schottky barrier heights for Au on chemically etched In_(x)Ga_(1-x)P surfaces

Measurements of the Au Schottky barrier height were carried out on thin films of n‐In_(x)Ga_(1−x)P, of various compositions epitaxially grown on n‐GaAs substrates. Conventional C–V, I–V, and photo response techniques were used. The junction was formed by evaporating Au in an ion‐pumped vacuum system onto a In_(x)Ga_(1−x)P surface which had been chemically etched (5H_(2)SO_(4):1H_(2)O_(2):1H_(2)O at 40 °C for 90 s). Barrier heights determined from the I–V and photoresponse were found to be in good agreement while the C–V measurement encountered difficulties. The Au barrier, ϕ_p, to p‐In_(x)Ga_(1−x)P was found to be independent of composition. The barrier, ϕ_p, was determined by the relation ϕ_(p) + ϕ_(n)=ϕ_(g) where ϕ_(g) is the bandgap energy and ϕn is the measured barrier to n‐In_(x)Ga_(1−x)P. It has been observed that the Au barrier height to p‐type material for most compound semiconductors is determined by the anion, thus p‐InP and p‐GaP have the same Au barrier, about 0.76 eV. This dependence on the anion of the compound has now been seen to extend to the alloy system In_(x)Ga_(1−x)P measured here. While chemically etched specimens yielded diodes with reproducible barrier heights, diodes formed on surfaces which were untreated or cleaned only with organic solvents were of poor quality with varying barrier heights or even ohmic contacts

HgTe/CdTe heterojunctions: A lattice-matched Schottky barrier structure

HgTe-CdTe lattice-matched heterojunctions were formed by the epitaxial growth of HgTe on CdTe substrates using a low-temperature metal organic chemical vapor deposition technique. These heterojunctions combine features of the Schottky barrier structure, due to the high carrier concentrations found in the semimetallic HgTe, with the structural perfection present in a lattice-matched heterojunction. The measured Schottky barrier height varied from 0.65 to 0.92 eV depending on the details of the heterojunction growth procedure used. This dependence may be due to the formation of an inversion layer in the CdTe at the interface. Presence of such an inversion layer suggests that the valence band discontinuity between HgTe and CdTe is small, in agreement with previous theoretical estimates

Application of selective epitaxy to fabrication of nanometer scale wire and dot structures

The selective growth of nanometer scale GaAs wire and dot structures using metalorganic vapor phase epitaxy is demonstrated. Spectrally resolved cathodoluminescence images as well as spectra from single dots and wires are presented. A blue shifting of the GaAs peak is observed as the size scale of the wires and dots decreases

Stability and pinning points in substrate-confined liquids

Confinement of liquid by concavities in a substrate surface is treated with reference to contemporary interest in growing semiconductor crystal on inert substrates. Instabilities that occur during or after filling of simple concavity shapes are considered, with particular attention to the influence of discontinuities of slope in the substrate

A DLTS study of deep levels in n-type CdTe

We report the results of a DLTS study on the majority carrier deep level structure of three samples of n-type CdTe and the effects on the deep level structure of indium doped CdTe due to H2 annealing. H2 annealing did not qualitatively change the deep level structure of the annealed sample. It did cause the shallow level concentration to decrease with a proportional decrease in the deep level concentrations as a result of indium out-diffusion and compensation by native defects. Levels present in all of the materials studied have been characterized and attributed to either native defects or innate chemical impurities. Other levels present in indium doped material require above band gap illumination of the sample before they are observed. A possible model proposes that these levels arise from defect complexes

The heteroepitaxy of Ge on Si: A comparison of chemical vapor and vacuum deposited layers

Epitaxial growth of Ge on Si has been investigated by two techniques: vacuum deposition and chemical vapor deposition (CVD). Vacuum-deposited Ge layers (physical vapor deposition, PVD) on heated Si substrates (≤ 500 °C) have smooth surface morphologies with a surface crystalline quality which improves with Ge layer thickness. Layers prepared by the CVD technique at 500–600 °C are comparable with the PVD prepared layers. Main defects in both PVD and CVD layers are dislocations initiating at the Ge/Si interface. Chemical vapor-deposited Ge layers grown at a substrate temperature of 700–800 °C exhibit poor crystalline quality and often are polycrystalline. Chemical vapor-deposited layers grown at a substrate temperature of 900 °C, again are good quality epitaxial layers. In this case, in addition to dislocations, stacking faults are present. All the studied layers are highly conductive and p-type. The conduction and valence band discontinuities determined from electrical measurements are 0.05±0.04 eV and 0.39±0.04 eV, respectively