Reactive ion etching of GaN using BCl3, BCl3/Ar and BCl3/N2 gas plasmas

Reactive ion etching (RIE) of GaN has been performed using BCl3 and additives, Ar and N-2 to BCl3 plasma. The etch rate, surface roughness and the etch profile have been investigated. The etch rate of GaN is found to be 104 nm/min at rf power of 200 W, pressure of 2 Pa, with 9.5 seem flow rate of BCl3. The addition of 5 seem of Ar to 9.5 seem of BCl3 reduces the etch rate of GaN while the addition of N-2 does not influence the etch rate significantly. The RIE of GaN layer with BCl3/Ar and BCl3/N-2 results in a smoother surface compared to surfaces etched with BCl3 only. The etched side-wall in BCl3 plasma makes an angle of 60 degrees with the normal surface, and the angle of inclination is more in cases of BCl3/Ar and BCl3/N-2 plasmas. The RIE induced damage to the surface is measured qualitatively by PL measurements. It is observed that the damage to the etched surfaces is similar for all the plasmas. (C) 2000 Elsevier Science Ltd. All rights reserved.