A NEW LUMINESCENCE SPECTRUM IN GaP
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Date
1971
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Ohio State University
Abstract
A new spectrum in p-type GaP has been observed which peaks at 2.120 eV at $6^{\circ} K$, in samples which are grown by water vapor transport method. The spectrum consists of a zero phonon line at 2.178 eV and local mode phonons side bands of energy 4.4 meV, as well as side bands due to TA and LO known phonons. The emission quenches rapidly with increasing temperature and an activation energy of 24 meV is deduced from the temperature dependence of the luminescent intensity. The samples at room temperature are p-type with acceptors either Zn (replacing Ga) or C (replacing phosphorous). The emission is tentatively identified as due to a complex involving Gallium vacancy ($V_{e}$) and a donor (possibly O+). On annealing at $600^{\circ} C$ for 15 hours, the spectrum quenches and in Zn doped crystal produces the known red (Zn-O) complex. The intensity of the green donor-acceptor pair spectrum also increases substantially, signifying that the vacancy-complex may be acting as a nonradiative center. Vacancy-complexes have been identified in GaAs and this would be the first evidence of a similar vacancy-complex in GaP. The radiative and nonradiative nature of such vacancy-complexes will be discussed.
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Author Institution: Philips Laboratories