Non-Monotonous Behavior of In-Doped GaN Grown by MOVPE with Nitrogen Carrier Gas

Abstract

This paper reports the In-doping effects in MOVPE grown GaN using a N 2 carrier gas. Electrical and optical properties of the In-doped GaN are found to show non-monotonous behavior, when the In source (TMI) supply is increased. Carrier concentration in the In-doped GaN is monotonously decreased with increasing TMI supply, while Hall mobility and PL intensity ratio between exciton emission and yellow deep emission (I EX /I YL ) are decreased in the region of low TMI supply (TMI/TEG < 0.5). In this region, tensile stress in the grown GaN estimated from the exciton emission peak energy is also increased with increasing TMI/TEG ratio. For TMI/TEG ratio in the range of 0.5-1.5, on the other hand, they show very normal behavior (improvement by In doping). Such anomalous behavior for mobility, I EX /I YL and tensile stress is discussed from the viewpoints of impurity hardening of GaN, as well as stress relaxation by both crack formation and In doping.