Crystallographic wet chemical etching of p-type GaN

We demonstrate crystallographic wet chemical etching of p-type GaN with etc h rates as high as 1.2 mu m/min. Etchants used include molten KOH, KOH diss olved in ethylene glycol, aqueous tetraethylammonium hydroxide, and phospho ric acid (H3PO4), at temperatures ranging from 90 to 260 degrees C. The obs erved crystallographic p-GaN etch planes are (0001), {10(1) over bar 0}, an d {<10(12)over bar>}. The etch rates follow an Arrhenius characteristic wit h activation energies varying from 21 kcal/mol for KOH-based solutions to 3 3 kcal/mol for H3PO4. The etch rate and crystallographic nature for the var ious etching solutions are independent of conductivity, as shown by seamles s etching of a p-GaN/undoped, high-resistivity GaN homojunction and by comp arison of the etch rates of p-GaN with n-GaN. (C) 2000 The Electrochemical Society. S0013-4651(99)06-134-0. All rights reserved.