In situ measurement of GaN film photoluminescence under plasma etching

This work focuses on an improved method that enables us to measure in situ GaN film photoluminescence (PL) under Ar or N2 plasma etching. Although the background signal is large and increases with bias voltage, the GaN PL can be obtained after subtraction of this background from the total luminescence. Moreover, after plasma etching, the intensities of the near-band-edge and the yellow luminescence decrease significantly. It is suggested that this behaviour is strongly related to the heavy plasma-induced damage, which includes non-radiative defects and deep-level defects, such as Ga vacancies and/or C impurities.