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Title: Change in equilibrium position of misfit dislocations at the GaN/sapphire interface by Si-ion implantation into sapphire—I. Microstructural characterization

Much research has been done to reduce dislocation densities for the growth of GaN on sapphire, but has paid little attention to the elastic behavior at the GaN/sapphire interface. In this study, we have examined effects of the addition of Si to a sapphire substrate on its elastic property and on the growth of GaN deposit. Si atoms are added to a c-plane sapphire substrate by ion implantation. The ion implantation results in scratches on the surface, and concomitantly, inhomogeneous distribution of Si. The scratch regions contain a higher concentration of Si than other regions of the sapphire substrate surface, high-temperature GaN being poorly grown there. However, high-temperature GaN is normally grown in the other regions. The GaN overlayer in the normally-grown regions is observed to have a lower TD density than the deposit on the bare sapphire substrate (with no Si accommodated). As compared with the film on an untreated, bare sapphire, the cathodoluminescence defect density decreases by 60 % for the GaN layer normally deposited on the Si-ion implanted sapphire. As confirmed by a strain mapping technique by transmission electron microscopy (geometric phase analysis), the addition of Si in the normally deposited regions forms a surface layer inmore » the sapphire elastically more compliant than the GaN overlayer. The results suggest that the layer can largely absorb the misfit strain at the interface, which produces the overlayer with a lower defect density. Our results highlight a direct correlation between threading-dislocation density in GaN deposits and the elastic behavior at the GaN/sapphire interface, opening up a new pathway to reduce threading-dislocation density in GaN deposits.« less
Authors:
; ;  [1] ;  [2] ; ; ;  [3]
  1. Department of Materials Science and Engineering and Research Institute of Advanced Materials (RIAM), Seoul National University, Seoul 151-744 (Korea, Republic of)
  2. Korea Photonics Technology Institute, Gwangju 500-779 (Korea, Republic of)
  3. Korea Basic Science Institute, Daejeon 305-806 (Korea, Republic of)
Publication Date:
OSTI Identifier:
22492277
Resource Type:
Journal Article
Resource Relation:
Journal Name: AIP Advances; Journal Volume: 5; Journal Issue: 7; Other Information: (c) 2015 Author(s); Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE; CATHODOLUMINESCENCE; COMPARATIVE EVALUATIONS; CONCENTRATION RATIO; CORRELATIONS; CRYSTAL GROWTH; DISLOCATIONS; ELASTICITY; GALLIUM NITRIDES; INTERFACES; LAYERS; MICROSTRUCTURE; PHASE STUDIES; SAPPHIRE; SILICON IONS; STRAINS; SUBSTRATES; SURFACES; TRANSMISSION ELECTRON MICROSCOPY