Optical absorption and emission of GaP sub 1 minus x Sb sub x alloys
- University of Utah, 304 EMRO, Salt Lake City, Utah 84112 (USA). Department of Electrical Engineering University of Utah, 304 EMRO, Salt Lake City, Utah 84112 (USA). Department of Material Science and Engineering
The first detailed optical investigation of the metastable III/V semiconductor alloy GaP{sub 1{minus}{ital x}}Sb{sub {ital x}} is presented. Epilayers are grown by atmospheric pressure organometallic vapor phase epitaxy throughout the entire compositional range on GaP, GaAs, and GaSb substrates. The approximately 1-{mu}m-thick layers are partially strained with values of lattice mismatch as large as 1.7{times}10{sup {minus}2}. Values of band gap are determined for the first time from absorption spectra measured at 10 and 300 K and corrected for strain-induced energy shifts. The resultant values of bowing parameter for the direct and indirect band gaps are {ital c}{sub {Gamma}}=3.11{plus minus}0.18 eV and {ital c}{sub {ital x}} =2.06{plus minus}0.18 eV, independent of temperature, yielding a value of direct/indirect crossover composition, {ital x}{sub {ital c}}, of 0.32{plus minus}0.07. Single photoluminescence (PL) peaks are observed between 10 and 300 K for all samples. For samples with 0.37{le}{ital x}{le}0.47, they are assigned to recombination of carriers localized in bandtail states induced by compositional fluctuations. The stretch of the tails into the gap is greatly enhanced over the random alloy limit by the metastability of the Ga{sub 1{minus}{ital x}}Sb{sub {ital x}} alloys. PL peaks for samples with {ital x}{le}0.32 are assigned to recombination via deep centers in the gap. The PL peak of a sample with {ital x}=0.91 is assigned to recombination involving shallow acceptors.
- DOE Contract Number:
- FG02-84ER45061
- OSTI ID:
- 6710519
- Journal Information:
- Journal of Applied Physics; (USA), Journal Name: Journal of Applied Physics; (USA) Vol. 68:2; ISSN 0021-8979; ISSN JAPIA
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
360603* -- Materials-- Properties
ABSORPTION SPECTRA
ANTIMONIDES
ANTIMONY COMPOUNDS
COATINGS
EPITAXY
GALLIUM ANTIMONIDES
GALLIUM COMPOUNDS
GALLIUM PHOSPHIDES
LAYERS
LUMINESCENCE
MEDIUM TEMPERATURE
PHOSPHIDES
PHOSPHORUS COMPOUNDS
PHOTOLUMINESCENCE
PNICTIDES
RECOMBINATION
SPECTRA
STRAINS
ULTRALOW TEMPERATURE
VAPOR DEPOSITED COATINGS