Deep electronic states associated with a metastable hole trap in n-type GaN

Deep level transient spectroscopy (DLTS) and high-resolution Laplace DLTS (LDLTS) have been applied to MOCVD-grown GaN to study the properties of a metastable hole trap which is unstable after thermal stress. Initially, three peaks due to electron emission at 150, 400 and 550 K were visible in the DLTS spectrum at a rate window of 200 s−1. However, when the next rate window was sampled immediately afterwards, the DLTS scan showed a large negative peak which dominated the scan at 410 K, due to hole emission. The hole trap then remained detectable by DLTS for up to 1 week. LDLTS of the hole trap was also carried out and multiple peaks were observed. Changing the fill pulse length did not affect the capture properties of this centre, and it is proposed that it is a charge state of the Ga vacancy complexed with one or more O atoms.