Schottky barrier formation for In deposited on GaAs(110): the low coverage limit (original) (raw)

Schottky barrier at the indium tin oxide -n-GaAs interface: Effect of surface arsenic deficiency

Thin Solid Films, 1990

In this paper we present the results of our studies on the Schottky barrier at the indium tin oxide (ITO)-n-GaAs interface and the effect of an arsenic-deficient GaAs surface on the barrier height. The ITO/n-GaAs junctions were prepared by depositing ITO (by a reactive thermal evaporation technique) on as-cleaned and heat-treated GaAs substrates of (100) orientation. The heat treatment of GaAs gave rise to an arsenic-deficient surface. The current-voltage characteristics of the Schottky diodes exhibit two current transport mechanisms: depletion region recombination and thermionic emission. The height of the Schottky barrier at the interface between ITO and as-cleaned GaAs is 0.83_+0.02eV and that at the interface of ITO and heat-treated GaAs is 1.05 __+ 0.02 eV as evaluated using I-V and C-V methods. The results are in accordance with the defect models for Schottky barrier formation. The junctions having an enhanced barrier exhibit a photoconversion efficiency of 7.75~, the highest for any ITO/GaAs junctions reported so far.

Adsorption of indium on an InAs wetting layer deposited on the GaAs(001) surface

Physical Review B, 2008

In this work we perform a first-principles study of the adsorption properties of an In adatom deposited on 1.75 monolayers (ML) InAs, forming a wetting layer on GaAs$(001)$ with the alpha_2(2times4)\alpha_2 (2\times4)alpha2(2times4) or beta2(2times4)\beta_2 (2\times4)beta2(2times4) reconstruction. The structural properties of these reconstructions have been studied: we determine the equilibrium geometry of the surfaces and their stability for various growth conditions. We have then carried out a detailed study of the potential energy surface (PES) for an In adsorbate, finding the minima and the saddle points. The main characteristics of the PES and the bonding configurations of the In adatom on the surface are analyzed by comparing with analogous studies reported in the literature, trying to extract the effects due to: (i) the compressive strain to which the InAs adlayer is subjected, (ii) the particular surface reconstruction, and (iii) the wetting layer composition. We found that, in general, stable adsorption sites are located at: (i) locations besides the As in-dimers, (ii) positions bridging two As in-dimers, (iii) between two adjacent ad-dimers (only in beta2\beta_2beta2), and (iv) locations bridging two As ad-dimers. We find also other shallower adsorption sites which are more reconstruction specific due to the lower symmetry of the alpha2\alpha_2alpha2 reconstruction compared to the beta2\beta_2beta_2 reconstruction.

Low coverage deposition of alkali metals on GaAs(110)

Applied Surface Science, 1992

An ab-initio LCAO method is used to calculate the electronic properties of different overlayers of Li, Na and K deposited on GaAs(llO). Results for a monolayer, half a monolayer and the isolated alkali metal atom are presented. Cnemisorption energies and the most favourable adsorption sites are calculated for each case. The interface Fermi cnerg2t and the Schonky harrier formation are discussed as a function of the metal coverage. An important conclusion is that for alkali atoms, the induced density of interface states model is operative for coverages larger than a half monolayer.

Schottky barrier heights on IV-IV compound semiconductors

Journal of Electronic Materials, 1996

The variations of Schottky barrier heights on Sil x GexC~ films with composition 9. .-y _and strata have been investigated and compared to those expected for the band gap energy. The barrier on n-type does not depend on composition and strain. This independence suggests that the Fermi level at the interface between tungsten and Sil x yGexCy alloys (x ~ 0) is pinned relative to the conduction-band. For Sii_xGe, the barrier on p-type follows the same trends as the band gap. For the ternary alloys, the variations of the barrier on p-type seem to be too large to be only due to a variation of the band-gap. In addition, we have investigated the influence of the deposition conditions of the sputtered-W-gate on the barrier to silicon and Sil_xGe x. Our results show that the barrier on n-type-Si and p-type-Sil_~Gex-films increases when the stress retained in the W-films changes from compressive to tensile as the deposition pressure increases. The absence of change in the barrier height of W to p-type-silicon and n-type-Si~_~Gex-films suggests that the Fermi level at the interface with Si is pinned relative to the valence-band while it is pinned relative to the conduction when Ge is added.

Schottky barrier heights of InxAl1−xAs (0≤x≤0.35) epilayers on GaAs

Journal of Applied Physics, 1995

The electrical characteristics of Al Schottky diodes on n-type h$l,_"tu (0<xS0.35) were investigated in deail. These high quality InAlAs epilayers were grown on GaAs using step-graded buffers under proper growth conditions. The Schottky barrier height of the epilayers increa,ses with Al content as opposed to what predicted previously. This is believed to be the first report on the Schottky barrier height of In,Al,.,As epilayers in this composition range.