Chemical reaction and charge redistribution at metal–semiconductor interfaces

Abstract

Interface compound formation and metal-induced surface states are observed at representative metal–semiconductor interfaces. These phenomena are associated with microscopic dipoles at the intimate contacts which account for the macroscopic Schottky barrier heights. The barrier heights exhibit a correlation with chemical reactivity and display a pronounced transition between reactive and unreactive interfaces. Thus, local charge redistribution rather than any intrinsic surface states of the semiconductor determine Schottky barrier formation at the metal–semiconductor interfaces.

Surface photovoltage phenomena: theory, experiment, and applications

“…For example, the Schottky barrier height in metal/semiconductor junctions is almost always found to agree, usually to better than 0.1 eV, with the position of the dominant surface states found by SPS [323,324,347,352,372,373]. This constitutes a direct experimental veri®cation of Bardeen's model of Fermi level pinning by surface states, discussed in Section 2.1.5 (see Fig.…”

“…Studies of the evolution of metal±semiconductor interfaces using SPS were pioneered by Mo Ènch et al [330] and by Brillson [323,372,373], with later studies being conducted mostly by Shapira et al [324,352,370] and Musatov et al [108,338,339,347]. An example is found in Fig.…”

“…An example is found in Fig. 54, [372] which features the evolution of SPV spectra of the CdS(1 0 1 0) surface with increasing Au overlayer thickness. While some surface states are already present at the cleaved surface, Au deposition introduces new surface states.…”

“…Brillson [363,364,372,373,375,376] has pioneered the use of SPS in tandem with chemical analytical tools in order to assess the impact of surface chemistry on surface electronic properties. An early study of Brillson, which merits some discussion here, has been the SPS analysis of the CdS(1 1 2 0) surface under various conditions and treatments, shown in Fig.…”

Front Matter

“…The lattice parameter studies date back to 1935 [1], vibrational properties were studied by Raman scattering in 1966 [2], detailed optical properties were investigated in 1954 [3], and its growth by chemical vapor transport was attained in 1970 [4]. In terms of devices, Au Schottky barriers were formed in 1965 [5], LEDs were demonstrated in 1967 [6] wherein Cu2O was used as the p-type material, metal insulator semiconductor (MIS) structures were reported in 1974 [7], ZnO/ZnTe n-p junctions were accomplished in 1975 [8], and Al/Au ohmic contacts were reported in 1978 [9]. Very high quality what used to be called whiskers and platelets, the nomenclature that gave way to nanostructure, of late, have been prepared early on and used to deduce much of the principal properties of this material, particularly the optical properties, albeit with a healthy debate about the valence band ordering and assignment of some of the peaks appearing in optical excitation measurements.…”