Yellow luminescence and related deep states in undoped GaN
- Departamento Ingenieria Electronica, ETSI Telecomunicacion, Universidad Politecnica, Ciudad Universitaria, 28040, Madrid (Spain)
- CRHEA--CNRS, Parc Sophia Antipolis, rue Bernard Gregory, 06560 Valbonne (France)
Photocapacitance spectra in undoped, metal-organic vapor-phase-epitaxy-grown GaN layers, in a range of photon energies from 0.6 to 3.5 eV, reveal two main persistent features: a broad increase of the capacitance from 2.0 to 2.5 eV, and a steep {ital decrease} at 1 eV, only observed after a previous light exposure to photon energies above 2.5 eV. A deep trap (E{sub v}+1 eV) that captures photoelectrons from the valence band, after being emptied with photons above 2.5 eV, is proposed as the origin of these features. Optical-current deep-level transient spectroscopy results also show the presence of a trap at 0.94 eV {ital above} the valence band, {ital only} detected after light excitation with photon energies above 2.5 eV. A correlation is found between the {open_quotes}yellow band{close_quotes} luminescence intensity at 2.2 eV and the amplitude of the photocapacitance decrease at 1 eV, pointing to a deep trap at 1 eV {ital above} the valence band as the recombination path for the yellow band. The detection of the yellow band with below-the-gap photoluminescence excitation supports the proposed model. {copyright} {ital 1997} {ital The American Physical Society}
- OSTI ID:
- 450425
- Journal Information:
- Physical Review, B: Condensed Matter, Vol. 55, Issue 7; Other Information: PBD: Feb 1997
- Country of Publication:
- United States
- Language:
- English
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