Effect of Heat Treatment of Al Substrate on GaN Film Electrodeposited in Aqueous Solution

Abstract

Most reports on the fabrication of high-quality Gallium nitride (GaN) are typically based on physical techniques that require very expensive equipment. Therefore, the electrodeposition was adopted and examined to develop a simple and economical method for GaN synthesis. GaN films are synthesized on aluminum substrates that are heat-treated at various temperatures using a low-cost and low-temperature electrochemical deposition technique. The electrochemical behavior of source ions in aqueous solutions is examined by cyclic voltammetry (CV). In the solution at pH 1.5 containing 0.1M Ga(NO 3 ) 3 , 2.5 M NH 4 NO 3 and 0.6 M H 3 BO 3 , reduction of gallium and nitrate ions are observed in CV. The presence of hexagonal GaN and gallium oxide (Ga 2 O 3 ) phases is detected for the films deposited on Al substrates at −3.5 mA•cm -2 for 3 h. The energy dispersive X-ray and mapping results reveal that Ga, O, and N coexist in these films. Raman analysis shows hexagonal GaN formation on Al substrates. The changes in the morphology and preferred orientation of GaN were found, which was caused by the reactivity of aluminum surface and the aluminum oxide layer formed by the heat treatment.