Anodic oxidation of gallium nitride

The anodic oxidation of n-type GaN (carrier concentration 4.6 x 10 exp 18/cu cm) under laboratory illumination at a constant current density of 5 mA/sq cm in sodium tungstate electrolyte is examined by high resolution microscopy and surface analysis. The GaN, deposited as a thin layer by molecular b...

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Bibliographic Details
Published in:Journal of materials science 2003-01, Vol.38 (2), p.343-349
Main Authors: PAKES, A, SKELDON, P, THOMPSON, G. E, FRASER, J. W, MOISA, S, SPROULE, G. I, GRAHAM, M. J, NEWCOMB, S. B
Format: Article
Language:English
Subjects:
Anodizing
Bonding strength
Carrier density
Condensed matter: structure, mechanical and thermal properties
Cross-disciplinary physics: materials science
rheology
Exact sciences and technology
Gallium nitrides
Gallium oxides
Materials science
Molecular beam epitaxy
Morphology
Nitrogen
Oxidation
Physics
Reaction products
Solid surfaces and solid-solid interfaces
Stoichiometry
Surface analysis (chemical)
Surface cleaning, etching, patterning
Surface structure and topography
Surface treatments
Surfaces and interfaces
thin films and whiskers (structure and nonelectronic properties)
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Summary:The anodic oxidation of n-type GaN (carrier concentration 4.6 x 10 exp 18/cu cm) under laboratory illumination at a constant current density of 5 mA/sq cm in sodium tungstate electrolyte is examined by high resolution microscopy and surface analysis. The GaN, deposited as a thin layer by molecular beam epitaxy, had an initially faceted surface. Anodic oxidation gives rise to local growth of an amorphous Ga2O3-based reaction product, often, but not exclusively, located in the vicinity of troughs formed by intersecting facets. At these regions dislocations in the GaN intersect the surface. The product is non-uniform in thickness and morphology, with pore-like features. With prolonged anodic treatment, local oxidation progresses as channels, which eventually reach the base of the GaN layer, leaving a porous skeleton. The formation of a uniform and compact film material on GaN is considered to be impeded by generation of nitrogen from the anodic reaction, with the strength of the Ga-N bonding focusing oxidation on regions of increased impurity, non-stoichiometry or defect concentration.
ISSN:0022-2461
1573-4803
DOI:10.1023/A:1021125918526