THE INFLUENCE OF CH4/H-2/AR PLASMA-ETCHING ON THE CONDUCTIVITY OF N-TYPE GALLIUM NITRIDE

The influence of plasma etching on the electrical properties of n-type gallium nitride (GaN) thin films has been investigated. Electron-cyclotron-resonance microwave plasma reactive ion etching in CH4/H-2/Ar, in CH4/H-2, and in H-2 results in an increase in the GaN layer's sheet carrier concentration and a decrease in the effective Hall mobility. Neither wet chemical etching nor etching in Cl-2 or BCl3 plasmas introduces similar changes. Therefore, the observed damage is considered to be related to the CH4/H-2/Ar plasma chemistry. in particular, it suggests hydrogen influence on the defect generation. Subsequent annealing of the affected GaN layers at 800 degrees C removes the plasma damage.