Mg-doped GaN: Similar defects in bulk crystals and layers grown on Al{sub 2}O{sub 3} by metal-organic chemical-vapor deposition
- Lawrence Berkeley National Laboratory, Berkeley, California 94720 (United States)
- High Pressure Research Center ''Unipress'', Polish Academy of Sciences, Warsaw, (Poland)
- Microelectronics Research Center, The University of Texas at Austin, Austin, Texas 78712-1100 (United States)
Defects were observed in GaN:Mg grown on sapphire substrates using metal-organic chemical-vapor deposition (MOCVD) with Mg-delta doping similar to those previously observed in bulk GaN:Mg grown from Ga solution under high hydrostatic pressure of nitrogen. Pyramidal defects (pinholes) with (11(bar sign)00) hexagonal facets on the (0001) base plane and six {l_brace}112(bar sign)2{r_brace} side facets, and defects with a rectangular shape also delineated by planar facets on the basal (0001) planes, were observed for growth with Ga polarity for both of these very different growth methods. The Mg dopant is apparently responsible for their formation since the oxygen concentration in the MOCVD-grown samples was orders of magnitude lower than in the bulk samples. Mg segregation on these planes apparently does not allow uniform continuous growth on these planes leading to these hollow defects. Some defects in the heterolayers also develop into longer nanotubes elongated along the c axis. Change of polarity from Ga to N followed by a change back to Ga polarity also resulted in formation of planar defects previously observed in bulk samples for growth with N polarity. (c) 1999 American Institute of Physics.
- OSTI ID:
- 20217759
- Journal Information:
- Applied Physics Letters, Journal Name: Applied Physics Letters Journal Issue: 26 Vol. 75; ISSN APPLAB; ISSN 0003-6951
- Country of Publication:
- United States
- Language:
- English
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