Generation of electrical damage in n-GaN films following treatment in a CF4 plasma

We have investigated the generation of electrical damage in n-GaN films following treatment in a CF4 plasma, employing capacitance-voltage and steady-state photocapacitance spectroscopy techniques. The effective carrier concentration at depths of 50-150nm from the GaN surface decreases, probably owing to Ga vacancies (V-Ga) diffusing into the bulk after being introduced at the surface by ion bombardment. These vacancies consequently form acceptor-type hydrogenated V-Ga with optical onsets at similar to 1.79 and similar to 3.23 eV below the conduction band. In particular, the dominant 3.23 eV level is most likely attributed to (V-Ga-H-2)(-) species, because the V-Ga concentration at depth is very low. (C) 2017 The Japan Society of Applied Physics