Nonstoichiometric deep levels in Mg-doped GaP epitaxial layers: Effects of pre-annealing of substrates |
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Authors: | Takenori Tanno Ken Suto Yutaka Oyama Jun-Ichi Nishizawa |
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Affiliation: | (1) Department of Materials Sciences, Tohoku University, 980-8579 Sendai, Japan;(2) Semiconductor Research Institute, 980-0862 Sendai, Japan |
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Abstract: | The effects of substrate pre-annealing on deep level density in Mg-doped GaP liquid-phase epitaxy (LPE) layers were investigated by photocapacitance measurement. With annealing under optimum phosphorus-vapor pressure, concentration of deep donor at EC — 1.9–2.1 eV increased in undoped GaP substrate. Deep level densities in Mg-doped layers were also affected by pre-annealing of the substrates. Densities of dominant deep levels at EV + 0.85 eV and EV + 1.5 eV were an order of magnitude reduced and, in contrast, the level at EC − 2.1 eV in Mg-doped layer increased with long pre-annealing. This level at EC − 2.1 eV is supposed to be involved with P-rich-type nonstoichiometric defects, such as phosphorus interstitial atoms diffused from the surface of the substrate. |
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Keywords: | GaP LPE photocapacitance heat treatment nonstoichiometric defect |
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