Dislocation movement in GaN films

Abstract

We demonstrate that significant dislocation movement occurs below the surface of heteroepitaxial c-plane GaN films during their growth by metalorganic vapor phase epitaxy. Dislocations move primarily by vacancy-assisted climb, which appears to be driven by the high in-plane biaxial stresses present during growth. Annealing low dislocation density (4.3×108 cm−2) GaN films promotes dislocation climb and thus reduces both dislocation densities and in-plane stresses (at high temperatures), independent of epilayer growth conditions.

Threading dislocation movement in AlGaN/GaN-on-Si high electron mobility transistors under high temperature reverse bias stressing

“…At low temperatures, the vacancy diffusion required for dislocation climb is difficult and so climb is unlikely to take place. 22 Secondly, the higher vacancy concentration expected in a region of high tensile stress would support climb that would result in dislocation motion away from the tensile region, 21 which is not what we observed in this work. Dislocation movement via glide is the more likely mechanism responsible for the observed increase in the TDD.…”

“…The stress-driven climb mechanism 21 is unlikely for our case because of two reasons. First, the stressing temperature (i.e.…”

“…• C) 21 where dislocation climb usually occurs. At low temperatures, the vacancy diffusion required for dislocation climb is difficult and so climb is unlikely to take place.…”

The effects of annealing on non-polar (1 1 2¯ 0) a-plane GaN films

“…In c-plane GaN, this process results in dislocation reduction and produces dislocation arrays aligned along the in-plane [1 1 2 0] direction [16,17]. High-temperature annealing treatments are also used widely to recover the crystalline damage introduced during ion implantation of c-plane films, a technique used to create dilute magnetic III-nitrides [18], to activate rare-earth doped III-nitrides [19], to promote contact formation [20] and to create doped regions for device fabrication purposes [21].…”

Electronic structure and local distortions in epitaxial ScGaN films

“…The GaN-onsapphire pseudo-substrate was grown using metalorganic vapour phase epitaxy (MOVPE) [12]. Details of the Sc x Ga 1-x N growth conditions have been reported previously [9] [13].…”