Study of excess carrier dynamics in polar, semi‐polar, and non‐polar (In,Ga)N epilayers and QWs

Abstract

AbstractWe studied carrier recombination and diffusion in GaN/sapphire templates, (In,Ga)N layers, and (In,Ga)N quantum well structures oriented along the polar [0001], semi‐polar [11‐22], and non‐polar [11‐20] orientations by means of light induced transient grating, differential transmission, and photoluminescence optical techniques. We show that the lifetime of excess carriers drops by orders of magnitude when changing the orientation from polar to non‐polar, both in GaN templates and (In,Ga)N layers. We attribute the shorter lifetime to carrier trapping by extended structural defects that are more abundant in non‐polar grown samples. In addition, we observe pronounced carrier localization effects in the semi‐ and non‐polar layers. We show that thick (In,Ga)N layers inherit the properties of the GaN templates. However, the thin quantum well structures show a lower carrier trapping activity. So, a better electrical quality can be assumed as compared to the thick (In,Ga)N layers. (© 2011 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)