Silver contact on GaAs (001) and InP (001)

Abstract

We report here the first results of our study of metal/III–V semiconductor contacts :Ag–GaAs (001) and Ag–InP (001). Clean GaAs (001) and InP (001) surfaces, under various conditions of stoichiometry, are obtained by ion etching followed by annealing and arsenic or phosphorous adsorption and carefully characterized by AES, LEED, and ELS. Using these techniques some correlations between surface stoichiometry, surface structures, and electronic surface states have been found. On these surfaces the metallization has been carried out by an MBE-like technique. The results obtained show that the Schottky barrier height changes according to the conditions of surface preparation. To explain these results, different hypotheses are discussed.

New aspects of K promoted nitridation of the InP(100) surface

“…5 Alkali metal was evaporated from thoroughly outgassed SAES getter sources. The surface cleanliness was verified by both the absence of any contamination-related structure in the photoelectron spectra and the sharp 1ϫ4 low-energy electron diffraction ͑LEED͒ pattern.…”

Silver on phosphorus-passivated (100) InP interface formation and microstructure

“…Various annealing procedures have been reported by Massies, Devoldere and Linh (1978). Anneals under UHV conditions at 350-5WC lead to a (001) indium (4 x 2) surface.…”

The Metal-Semiconductor Interface

“…the substrate is Ga-stabilized, ~b is ~60 meV greater than when the substrate is As-stabilized. Silver contacts on (100) GaAs have been studied in some detail and show a similar sensitivity to surface stoichiometry, as well as to impurities (49). A recent proposal ascribes the pinning of the Fermi level, as the interface is formed, to anion deficiencies (68,69).…”

“…Stoichiometric effects on q5 have been found (49), and interdiffusion can clearly affect ~b (75). As mentioned earlier, dramatic effects on q5 arise from the choice of crystal face on which metal is deposited.…”

“…These give a ~0.5 eV barrier when deposited on clean (110) InP room temperature, but give ohmic contact when one-half monolayer of oxygen or chlorine is present on the InP prior to metal deposition. On the other hand, Farrow (48) and Massies et al (49) find that even Ag clean lnP gives ohmic contact provided that the crystal face exposed is (100). These results suggest that interface chemical reaction is an important consideration in InP.…”