Introduction of metastable vacancy defects in electron-irradiated semi-insulating GaAs
- Laboratory of Physics, Helsinki University of Technology, 02150 Espoo (Finland)
- Institut National des Sciences et Techniques Nucleaires, Centre d`Etudes Nucleaires de Saclay, 91191 Gif-sur-Yvette Cedex (France)
Positron-lifetime experiments have been performed to investigate the metastability of the point defects produced in the electron irradiation of semi-insulating GaAs. The measurements in darkness indicate the presence of Ga vacancies and Ga antisite defects in a negative charge state. Illumination at 25 K reveals another type of a defect, which has a vacancy in its metastable state. The metastable vacancies can be observed most effectively after illumination with 1.1-eV photons and they are persistent up to the annealing temperature of 80--100 K. The introduction rate of the metastable defects is about 0.3 cm{sup {minus}1}, which is close to the values reported earlier for the As antisite. The metastable properties of the defects resemble those of the well-known {ital EL}2 center in as-grown GaAs. We associate these defects to As antisites, which exhibit the metastability predicted by the theory: in the metastable configuration the As antisite atom relaxes away from the lattice position, leaving a Ga site vacant.
- OSTI ID:
- 165342
- Journal Information:
- Physical Review, B: Condensed Matter, Vol. 51, Issue 20; Other Information: PBD: 15 May 1995
- Country of Publication:
- United States
- Language:
- English
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