Metals—Group III—V compounds

Since the interpretation of interface behaviour from such measurements is critically dependent on the morphology of the metal film, we will deal with this problem first. No electron micrographs are available, so structure must be deduced from spectroscopic data. For very thin films, the development of the Au 5d bands provides the relevant information. The 

The proposed interaction model involves the formation of an Al coverage to 0.1 monolayer, with very little penetration of Al into the lattice, but with increasing Al deposition there is an increasing tendency for Al to replace Ga. The thermodynamic driving force is the higher heat of formation of AlAs than GaAs (117 kJ mole-1, cf. 71 kJ mole-1). It is speculated that the initial surface accumulation arises because a Ga surface vacancy, created thermally by Al adsorption, will more probably be refilled by a Ga atom until a comparatively large Al population has formed. In 

The adsorption mechanism has been studied by a combination of LEED, AES and work function changes [317, 319—321]. At room temperature, Cs adsorbs on 110 GaAs in an ordered c(4 x 4) structure for coverages around one monolayer [317, 321] and although the symmetry 

We may conclude, however, that probably as the result of a strong ionic contribution to the bonding, this system appears more straightforward than other metal—semiconductor combinations, at least with regard to interface instability. 

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