Spontaneous excitonic luminescence in GaSe in investigated from 80 to 300 K and at weak laser excitation intensity. Radiative recombinations of direct and indirect free excitons are clearly observed. The analysis of the emission lines as a function of the temperature, of the excitation intensity, and of laser energy permits to attribute two lines of the intrinsic luminescence to the recombination of direct and indirect excitons bound to defect centers localized in the energy gap. On the basis of recent theories on exciton-impurity complexes, it is found that in the crystals the excitonic binding centers are deep neutral acceptors. From the dissociation energy of the bound excitons the ionization energy of the acceptor levels is estimated. Moreover, the measurements seem to indicate that thermal equilibrium between direct and indirect excitonic states is lacking below about 100 K.
Radiative Decay from Free and Bound Excitons in GaSe
CAPOZZI, VITO GIACOMO;
1985-01-01
Abstract
Spontaneous excitonic luminescence in GaSe in investigated from 80 to 300 K and at weak laser excitation intensity. Radiative recombinations of direct and indirect free excitons are clearly observed. The analysis of the emission lines as a function of the temperature, of the excitation intensity, and of laser energy permits to attribute two lines of the intrinsic luminescence to the recombination of direct and indirect excitons bound to defect centers localized in the energy gap. On the basis of recent theories on exciton-impurity complexes, it is found that in the crystals the excitonic binding centers are deep neutral acceptors. From the dissociation energy of the bound excitons the ionization energy of the acceptor levels is estimated. Moreover, the measurements seem to indicate that thermal equilibrium between direct and indirect excitonic states is lacking below about 100 K.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
