TITLE

Light emission and microstructure of Mg-doped AlGaN grown on patterned sapphire

AUTHOR(S)
Bell, A.; Liu, R.; Ponce, F. A.; Amano, H.; Akasaki, I.; Cherns, D.
PUB. DATE
January 2003
SOURCE
Applied Physics Letters;1/20/2003, Vol. 82 Issue 3, p349
SOURCE TYPE
Academic Journal
DOC. TYPE
Article
ABSTRACT
Distinct crystalline and optical properties have been observed in Mg-doped Al[SUB0.03]Ga[SUB0.97]N grown on a patterned sapphire substrate; the pattern consisting of etched trenches along the sapphire 〈11&2macr;0〉 direction. The epilayer has two distinct regions: one grown directly onto the sapphire mesa and the other an epitaxial lateral overgrowth (ELO) region that overhangs the trench. Transmission electron microscopy shows the presence of pyramidal defects as well as large dislocation densities in the region grown directly on sapphire. In contrast, the ELO region is defect free and contains no Mg-related pyramidal defects. Cathodoluminescence measurements show superior near-band-edge emission in the ELO region, suggesting that the emission is susceptible to nonradiative centers caused by the high defect density in the rest of the sample. The Mg-related donor-acceptor-pair emission is fairly uniform throughout the film, indicating that it is not affected by the nonradiative centers. These optical and structural properties of AlGaN are closely related to the direction of the growth front.
ACCESSION #
8926081

 

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