Effect of the finishing treatment of a gallium arsenide surface on the spectrum of electron states in $n$-GaAs (100)

Deep level transient spectroscopy has been used to study the effect of substrate pretreatment on the spectrum of electron states in Au/$n$-GaAs(100) Schottky diodes. Two bands of energy-distributed states have been found near the metal/semiconductor interface. The first band appears in the spectra at temperatures of 200–300 K because elemental arsenic accumulates on the surface in clusters in the course of oxide formation in samples exposed to air. Surface disorder in the course of selective etching gives rise to the second band at 100–250 K. Annealing in selenium vapor heals defects in the surface region and removes both bands from the spectra. Samples annealed in Se$_2$ contain only the set of levels characteristic of bulk GaAs.