Growth of GaAs Oxide Layer Using Photoelectrochemical Method

Abstract

It is demonstrated that an oxide layer can be formed on the GaAs surface using the photoelectrochemical (PEC) method when the pH value of the electrolyte solution of HCl is ∼3.5. To study the effect of thermal treatment on the resulted GaAs oxide films, the as-grown samples were thermally treated at 200, 300, and 400°C in O2 ambiance for 10, 20, 30, and 40 min. The Auger electron spectroscopy measurement indicated that the resulted layers were composed of O, Ga, and As, and the elements ratio of O(Ga+As) of the as-grown layer and the layers annealed at 200, 300, and 400°C in O2 ambience were 1.39, 1.43, 1.51, and 1.52, respectively, being close to the value for Ga2 O3 and As2 O3. The X-ray photoelectron spectroscopy analysis showed that the bonding structure in the layer is Ga-O or As-O. These results confirmed that the layer could be identified as Ga2 O3 and As2 O3, mainly the former. It is also demonstrated that when the oxide layers were thermally treated in O2 ambiance, the GaAs oxide films became denser, the microstructure of the oxide changed from an amorphous to a polycrystalline structure, and the surface roughness of the oxide layer also changed. It is expected that the oxide GaAs layer grown by the PEC method would replace the externally deposited oxide layers to avoid the influence of surface contaminates and to be used as an insulating layer in various devices. © 2008 The Electrochemical Society.