Passivation of the GaP(111) surface by treatment in selenium vapors

Results of examination of structural phase transitions on the GaP(111) surface after heat treatment in selenium vapors in a vacuum chamber with a quasi-closed volume are described. The electrophysical characteristics of Schottky-barrier diodes on GaP(111) are studied before and after treatment in selenium vapors by measuring the current-voltage characteristics and by deep-level transient spectroscopy. It is found that, after treatment in selenium vapors, the Schottky-barrier height becomes dependent on the work function of the metal in accordance with the Schottky–Mott rule for an ideal diode. It is shown that a decrease in the density of surface electronic states in GaP(111) results from the formation of a Ga$_2$Se$_3$(111) $(\sqrt{3}\times\sqrt{3})$-$R$30$^\circ$ surface phase with ordered stoichiometric gallium vacancies.