New and unified model for Schottky barrier and III–V insulator interface states formation

For n- and p-doped III-V compounds, Fermi-level pinning and accompanying phenomena of the (110) cleavage surface have been studied carefully using photoemission at hv≲ 300 eV (so that core as well as valence band levels could be studied). Both the clean surfaces and the changes produced, as metals or oxygen are added to those surfaces in submonolayer quantities, have been examined. It is found that, in general, the Fermi level stabilizes after a small fraction of a monolayer of either metal or oxygen atoms have been placed on the surface. Most strikingly, Fermi-level pinning produced on a given semiconductor by metals and oxygen are similar. However, there is a strong difference in these pinning positions depending on the semiconductor: The pinning position is near (1) the conduction band maximum (CBM) for InP, (2) midgap for GaAs, and (3) the valence band maximum (VBM) for GaSb. The similarity in the pinning position on a given semiconductor produced by both metals and oxygen suggests that the states responsible for the pinning resulted from interaction between the adatoms and the semiconductor. Support for formation of defect levels in the semiconductor at or near the surface is found in the appearance of semiconductor atoms in the metal and in disorder in the valence band with a few percent of oxygen. Based on the available information on Fermi energy pinning, a model is developed for each semiconductor with two different electronic levels which are produced by removal of anions or cations from their normal positions in the surface region of the semiconductors. The pinning levels have the following locations, with respect to the VBM: GaAs, 0.75 and 0.5 eV; InP, 0.9 and 1.2 eV (all levels + 0.1 eV).

[1]  C. Su,et al.  Oxidation of ordered and disordered GaAs(110) , 1979 .

[2]  J. Joannopoulos,et al.  Electronic structure of Al chemisorbed on GaAs(110) , 1979 .

[3]  R. S. Bauer,et al.  Chemically induced charge redistribution at Al-GaAs interfaces , 1979 .

[4]  L. Meiners.  Surface potential of anodized p‐GaAs MOS capacitors , 1978 .

[5]  D. Chadi.  (110) surface states of GaAs and matrix element effects in angle‐resolved photoemission , 1978 .

[6]  P. Pianetta,et al.  New phenomena in Schottky barrier formation on III–V compounds , 1978 .

[7]  P. Pianetta,et al.  UPS and LEED studies of GaAs (110) and (111) As surfaces , 1978 .

[8]  A. Kahn,et al.  SURFACE AND NEAR-SURFACE ATOMIC STRUCTURE OF GaAs (110). , 1978 .

[9]  P. Pianetta,et al.  Evidence for a new type of metal-semiconductor interaction on GaSb , 1978 .

[10]  P. Pianetta,et al.  Valence band studies of clean and oxygen exposed GaAs(100) surfaces , 1978 .

[11]  P. Pianetta,et al.  Reply to "Oxidation properties of GaAs (110) surfaces" by R. Ludeke , 1977 .

[12]  P. Pianetta,et al.  A comparison of LEED intensity data from chemically polished and cleaved GaAs(110) surfaces , 1977 .

[13]  P. Pianetta,et al.  Studies of Surface Electronic Structure and Surface Chemistry Using Synchrotron Radiation , 1977 .

[14]  L. Messick,et al.  Electrical properties of anodic and pyrolytic dielectrics on gallium arsenide , 1977 .

[15]  P. Pianetta,et al.  Surface and interface states on GaAs(110): Effects of atomic and electronic rearrangements , 1977 .

[16]  P. Pianetta,et al.  Oxygen sorption and excitonic effects on GaAs surfaces , 1977 .

[17]  D. Eastman,et al.  Electronic surface properties of III–V semiconductors: Excitonic effects, band‐bending effects, and interactions with Au and O adsorbate layers , 1976 .

[18]  C. Duke,et al.  Atomic geometry of cleavage surfaces of tetrahedrally coordinated compound semiconductors , 1976 .

[19]  P. Pianetta,et al.  Synchrotron radiation studies of electronic structure and surface chemistry of GaAs, GaSb, and InP , 1976 .

[20]  J. Nakai,et al.  Surface Potential and Surface State Density in Anodized GaAs MOS Capacitors , 1976 .

[21]  W. Harrison.  Surface reconstruction on semiconductors , 1976 .

[22]  W. Spicer,et al.  Photoemission studies of the GaAs-Cs interface , 1975 .

[23]  D. Eastman,et al.  Photoemission Partial Yield Measurements of Unoccupied Intrinsic Surface States for Ge(111) and GaAs(110) , 1974 .

[24]  W. Spicer,et al.  Photoemission study of the effect of bulk doping and oxygen exposure on silicon surface states , 1974 .

[25]  W. Gudat,et al.  Close Similarity between Photoelectric Yield and Photoabsorption Spectra in the Soft-X-Ray Range , 1972 .

[26]  J. J. Scheer,et al.  Influence of volume dope on Fermi level position at gallium arsenide surfaces , 1967 .

[27]  Y. J. V. D. Meulen.  Growth properties of GaSb: The structure of the residual acceptor centres , 1967 .

[28]  G. Gobeli,et al.  Chapter 6 Low Energy Electron Diffraction Studies , 1966 .

[29]  Volker Heine,et al.  Theory of Surface States , 1965 .

[30]  G. W. Gobeli,et al.  Photoelectric Properties of Cleaved GaAs, GaSb, InAs, and InSb Surfaces; Comparison with Si and Ge , 1965 .

[31]  Carver A. Mead,et al.  Fermi Level Position at Metal-Semiconductor Interfaces , 1964 .