Evidence for exciton binding at Ni impurity sites in ZnSe |
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Authors: | SG Bishop DJ Robbins PJ Dean |
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Institution: | Royal Signals and Radar Establishment, St Andrews Road, Great Malvern, Worcs., England |
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Abstract: | A broad charge transfer band is observed in the photoluminescence excitation (PLE) spectrum of the 2.5 μ Ni2+ luminescence in ZnSe : Ni. This band lies above the highest energy d-d excitation bands and exhibits a ZPL at 1.8163 eV and LO(#38;0lambda;) phonon replicas at higher energy. In contrast, PLE spectra of Co2+ luminescence in ZnSe:Co contain only d-d excitation bands. The charge transfer band in ZnSe:Ni is interpreted as evidence for bound exciton formation at the Ni site. The recombination energy of this exciton is transferred efficiently to the excited d-band states of the Ni ion, leading to characteristic Ni2+d-d luminescence. |
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