Oxidation of GaP in an Aqueous H 2 O 2 Solution

Abstract

The oxidation of GaP in aqueous has been accomplished by both galvanic action at ∼100°C and by externally applied anodic reaction at room temperature. Films as thick as 1400 and 3500Aå, respectively, have been prepared using these two approaches. A detailed examination of the kinetics of galvanic oxide growth indicates that: (i) the oxidation mechanism involves predominantly the transfer of holes, (ii) the rate‐controlling step in the growth mechanism involves the diffusion of the oxidant, through the grown oxide, (iii) the index of refraction of the grown oxide is 1.58 ± 0.01, and (iv) a drying procedure to remove the water of hydration is necessary in order that the passivating amorphous oxide required for device use may be obtained. The growth of an oxide by externally applied anodic bias has resulted in the facts that: (i) the oxide thickness is linearly dependent on the applied bias up to about 100V, with the constant of proportionality being , (ii) an upper forming voltage of about 200V has been found for obtaining uniformly colored (i.e., thickness) films, and (iii) the index of refraction of the grown films depends on the forming voltage used, and (iv) a drying procedure to remove the water of hydration is necessary in order to obtain a stable amorphous oxide.