Shallow to deep transformation of Se donors in GaSb under hydrostatic pressure
- Instituto de Investigacion en Comunicacion Optica, Universidad Autonoma de San Luis Potosi, Alvaro Obregon 64, San Luis Potosi, S.L.P., (Mexico) 78000
- Department of Physics, University of California, Berkeley, California 94720 (United States)
- Center for Advanced Materials, Materials Science Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720 (United States)
We have observed that highly doped GaSb:Se, which is opaque to far IR radiation, becomes transparent at hydrostatic pressures above 9.8{plus_minus}2&hthinsp;kbar. We discuss how this behavior may be explained by the transformation of Se shallow donors into Se-DX (where DX is the unknown donor or X donor) centers in GaSb. Under this assumption the position of the Se-DX energy level at zero pressure is calculated to lie 80{plus_minus}30 meV above the conduction band at atmospheric pressure. The onset of transparency allowed us to observe several multiphonon absorbance features. We assign six of them to two-phonon absorptions. From the measured pressure dependence of the TO phonon, the Gr{umlt u}neisen parameter for this compound is calculated to be {gamma}{sub TO}=1.23{plus_minus}0.18. No persistent photoconductivity is observed for these Se-DX centers, a fact that may be explained by the expectation that the optical energy necessary to transform them back into the shallow form is larger than the band-gap energy of GaSb at all pressures examined, although it may be also an indication that the Se shallow donors change to deep donors associated with the L{sub 1} minima of ionization energy larger than 90 meV. {copyright} {ital 1999} {ital The American Physical Society}
- OSTI ID:
- 341176
- Journal Information:
- Physical Review, B: Condensed Matter, Vol. 59, Issue 12; Other Information: PBD: Mar 1999
- Country of Publication:
- United States
- Language:
- English
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