Inductively coupled plasma etching of doped GaN films with Cl₂/Ar discharges

The inductively coupled plasma etching of undoped n- and p-type GaN films was carried out with Cl₂/Ar discharges using different radio frequencies of 100 kHz and 13.56 MHz, in which the chuck power source operates. The etch rates with lower frequency of 100 kHz were greater than those with higher frequency of 13.56% MHz due to higher ion bombarding energy. The etch rates of the GaN films with 100 kHz frequency increased substantially with increasing pressure, while the etch rates with 13.56% MHz increased up to 20 mTorr and then decreased at higher pressures. The n-GaN showed somewhat faster etch rates than undoped and p-type GaN films. The surface of the etched GaN films showed quite smooth morphology, and the n-GaN showed some depletion of nitrogen from the etched surface.