Large surface Fermi level shift in high temperature annealed metal–insulator–GaAs structures prepared in the presence of oxygen

Abstract

Experiments were conducted on two types of GaAs substrates according to the surface treatment which either resulted in oxidation of the substrate (chemical etching) or in nearly oxygen-free interface (exposure of the substrate to a hydrogen/nitrogen mixture plasma). Owing to appropriate choices of the sequences of technological steps in the preparation of MIS samples, which include substrate treatment, deposition of the insulator (alumina obtained by reactive evaporation), and high temperature anneal (around 550 °C), it is given evidence of the great importance of the high temperature annealing step, solely responsible for the observed improvement in the electrical properties of the interface (as derived from capacitance and conductance measurements).

Nitridation and CVD reactions with hydazine

“…Nitridation with ammonia or nitrogen requires temperatures in excess of 800°C (Faulkner et al, 1970;Ishenvood and Wickenden, 1970;Prochazkova and Srobar et al, 1977;Matsuno et al, 1980). Plasma, ion, and photon beams can lower the nitridation reaction temperature, but high-energy particles and photons in these processes can damage the surface layers of the crystalline semiconductors (Gourrier et al, 1983(Gourrier et al, , 1985Friedel and Landesman, 1987;Blanchet et al, 1984;Berger et al, 1990;Troost et al, 1991;Sawada et al, 1987;Guizot et al, 1989).…”