Influence of potassium hydroxide molarity and etching time on etching of Al-rich aluminium gallium nitride layer

Abstract

In this work, n-doped AlGaN layer with a high Al composition of around 70% were etched using KOH solution. The molarity of KOH and the etching time were varied. With KOH molarity of 5 mol/L, no significant change in the formation of hexagonal pores, for 5 min etching and 10 min etching, was observed. Similar behaviour was also observed for the etching with 10 mol/L of KOH, which was carried out for 5 min. Nonetheless, with 10 mol/L of KOH, regardless of etching time, some of the Ga atoms were removed from the AlGaN lattice structure, resulting in AlGaN material with slightly higher Al composition. Besides, interestingly, bigger hexagonal pores (in macro scales) were formed when the etching was carried-out for 10 min using 10 mol/L of KOH. However, oxygen-containing materials were detected on the surface.