Data for reference ning-jmr-11-580

Growth defects in GaN films on sapphire: The probable origin of threading dislocations

X. J. Ning, F. R. Chien, P. Pirouz , J. W. Yang, M. Asif Khan

Journal of Materials Research 11(3), 580 (1996).

Single crystal GaN films with a wurtzite structure were grown on the basal plane of sapphire. A high density of threading dislocations parallel to the c-axis crossed the film from the interface to the film surface. They were found to have a predominantly edge character with a 1/3< (left-angle) 1120> (right-angle) Burgers vector. In addition, dislocation half-loops, elongated along the c-axis of GaN, was also found on the prism planes. These dislocations had a mostly screw character with a [0001] Burgers vector. Substrate surface steps with a height of 1/6cAl2O3, were found to be accommodated by localized elastic bending of GaN (0001)GaN planes in the vicinity of the film/substrate interface. Observations show that the region of the film, with a thickness of ~= (approximately-equal-to) 100 nm, adjacent to the interface is highly defective. This region is thought to correspond to the low-temperature GaN ``buffer'' layer which is initially grown on the sapphire substrate. Based on the experimental observations, a model for the formation of the majority threading dislocations in the film is proposed. The analysis of the results leads us to conclude that the film is under residual biaxial compression. © 1996 Materials Research Society.

This item is cited by the following items in the database:

  1. Microstructure, growth mechanisms and electro-optical properties of heteroepitaxial GaN layers on sapphire (0001) substrates
  2. Initial Growth Prismatic Domains in Cyclotron Assisted MBE of GaN/SiC
  3. Surface Treatment and Layer Structure in 2H-GaN Grown on the (0001)Si surface of 6H-SiC by MBE
  4. Defect structure in selectively grown GaN films with low threading dislocation density

Contributed by Philippe Vermaut from 192.93.101.126 on Tuesday, June 11, 1996 5:11:21 AM
Modified by Andrei Nikolaev from shuttle.ioffe.rssi.ru

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