Field effect on positron diffusion in semi-insulating GaAs
- Department of Physics, Brookhaven National Laboratory, Upton, New York 11793 (United States)
- Department of Physics, The University of Hong Kong (Hong Kong)
An energy-tunable monoenergetic positron beam was used to study positron diffusion in the space-charge region of an Au/GaAs(SI) (semi-insulating) Schottky contact, where the electric field reaches {approximately}10{sup 5} Vcm{sup {minus}1} by reverse biasing the diode. An analytical solution of the time-dependent positron drift-diffusion model under an electric field was obtained for the case of a semi-infinite body with a capturing boundary, and explains the experimental results well. A positron diffusion coefficient of 1.8{plus_minus}0.2 cm{sup 2}s{sup {minus}1}, and a positron mobility of 70{plus_minus}10 cm{sup 2}V{sup {minus}1}s{sup {minus}1} in GaAs(SI) at 300 K, were obtained independently. This result is consistent with the Einstein relation. The dependence of the positron current density at the Au/GaAs interface on the electric field shows that GaAs(SI) is a possible candidate for the fabrication of the field-assisted positron moderator. {copyright} {ital 1996 The American Physical Society.}
- Research Organization:
- Brookhaven National Lab. (BNL), Upton, NY (United States)
- DOE Contract Number:
- AC02-76CH00016
- OSTI ID:
- 288750
- Journal Information:
- Physical Review, B: Condensed Matter, Vol. 54, Issue 3; Other Information: PBD: Jul 1996
- Country of Publication:
- United States
- Language:
- English
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