Structural transition control of laterally overgrown c‐GaN and h‐GaN on stripe‐patterned GaAs (001) substrates by MOVPE

Abstract

AbstractGrowth mechanisms and material quality of the laterally overgrown cubic‐phase gallium nitride (c‐GaN) and hexagonal‐phase gallium nitride (h‐GaN) on stripe‐patterned GaAs (001) substrates were investigated using transmission electron microscopy (TEM). Investigational results show that h‐GaN is only laterally overgrown along the (111)B facets of the c‐GaN stripes with the growth direction of (0001)h‐GaN//(111)B c‐GaN for all the mask stripe orientations. Dislocation density in the laterally overgrown h‐GaN regions for the [110]‐stripe pattern is reduced to be lower than 104 cm–2, which is six orders of magnitude smaller than that in the conventionally grown h‐GaN films. On the other hand, the laterally overgrown c‐GaN with lower planar defect (stacking faults and twins) density presents in the region just above the stripe windows for the [1$ \bar 1 $0]‐stripe pattern. In addition, a large reduction of planar defect density was found in the laterally overgrown c‐GaN regions for the [100] stripe direction. Also, a model is used to describe the cubic‐to‐hexagonal structural transition in lateral‐overgrown GaN on patterned GaAs (001) substrates for the purpose of lower dislocation and lower planar defect densities in the laterally overgrown h‐GaN and c‐GaN, respectively. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)