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Defects in GaAs grown by molecular-beam epitaxy at low temperatures: stoichiometry, doping, and deactivation of n-type conductivity
- Source :
- Journal of Applied Physics. 86:1888-1897
- Publication Year :
- 1999
- Publisher :
- AIP Publishing, 1999.
-
Abstract
- We use a low-energy positron beam to study the influence of doping and stoichiometry on the native defects in GaAs grown by molecular-beam epitaxy at 250 °C. Ga vacancies are identified in all samples by measuring the momentum distribution of annihilating core electrons. The charge of VGa is negative in Si-doped samples but neutral in undoped and Be-doped material. We propose that the Ga vacancies are complexed with As antisites in undoped and Be-doped samples and with Si impurities in n-type material. The concentration of Ga vacancies depends on the doping and stoichiometry of growth conditions. It follows generally the trends in the VGa formation energy as a function of the Fermi level position and stoichiometry. The strong loss of free carriers in the As-rich Si-doped samples is attributed to the formation of Ga vacancy complexes, negative ion defects and inactive clusters of Si atoms.
- Subjects :
- Materials science
Condensed matter physics
Doping
Fermi level
Analytical chemistry
General Physics and Astronomy
Epitaxy
Condensed Matter::Materials Science
symbols.namesake
Core electron
Electrical resistivity and conductivity
Condensed Matter::Superconductivity
Vacancy defect
symbols
Condensed Matter::Strongly Correlated Electrons
Stoichiometry
Molecular beam epitaxy
Subjects
Details
- ISSN :
- 10897550 and 00218979
- Volume :
- 86
- Database :
- OpenAIRE
- Journal :
- Journal of Applied Physics
- Accession number :
- edsair.doi...........d85945d509f69459fa313fa7928f1c00