Investigation on the lattice site location of the excess arsenic atoms in GaAs layers grown by low temperature molecular beam epitaxy
We have measured the excess As atoms present in gaze layers grown by molecular beam epitaxy at low substrate temperatures using particle induced x-ray emission technique. The amount of excess As atoms in layers grown by MBE at 200{degrees}C were found to be {approximately} 4 {times} 10{sup 20} cm{sup {minus}2}. Subsequent annealing of the layers under As overpressure at 600{degrees}C did not result in any substantial As loss. However, transmission electron microscopy revealed that As precipitates (2-5nm in diameter) were present in the annealed layers. The lattice location of the excess As atoms in the as grown layers was investigated by ion channeling methods. Angular scans were performed in the <110> axis of the crystal. Our results strongly suggest that a large fraction of these excess As atoms are located in an interstitial position close to an As row. These As intersitials'' are located at a site slightly displaced from the tetrahedral site in a diamond cubic lattice. No interstitial As signal is observed in the annealed layers.
- Research Organization:
- Lawrence Berkeley Lab., CA (United States)
- Sponsoring Organization:
- DOE; USDOE, Washington, DC (United States)
- DOE Contract Number:
- AC03-76SF00098
- OSTI ID:
- 5928663
- Report Number(s):
- LBL-30990; CONF-911202--60; ON: DE92008253
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
360602* -- Other Materials-- Structure & Phase Studies
ARSENIC
ARSENIC COMPOUNDS
ARSENIDES
CHANNELING
CRYSTAL DEFECTS
CRYSTAL STRUCTURE
ELEMENTS
EPITAXY
FILMS
GALLIUM ARSENIDES
GALLIUM COMPOUNDS
ION CHANNELING
MOLECULAR BEAM EPITAXY
PNICTIDES
SEMIMETALS
SUBSTRATES
THIN FILMS