INVESTIGATION OF NITROGEN-RELATED ACCEPTOR CENTERS IN INDIUM SELENIDEBY MEANS OF PHOTOLUMINESCENCE - DETERMINATION OF THE HOLE EFFECTIVE-MASS

In this work we report on steady-state and time-resolved photoluminesc ence (PL) measurements in nitrogen-doped p-type indium selenide in the 33-210-K temperature range. In samples with low nitrogen concentratio n the photoluminescence spectrum consists of exciton-related peaks and a band-to-acceptor recombination peak (2.1-mu s lifetime) with LO-pho non replica. An ionization energy of 65.5 meV is proposed for the nitr ogen related acceptor. A long-lived (18 mu s) component, which consist s of an asymmetric broadband centered around the acceptor peak, has be en also detected by means of time-resolved FL. Samples with a higher n itrogen concentration show a PL spectrum that mainly consists of the a symmetric long-lived broadband that can be associated to a complex cen ter. The asymmetric shape of this band is quantitatively accounted for in the framework of the configuration coordinate model for complex ce nters. Under the assumption that the nitrogen-related acceptor is shal low, the Gerlach-Pollman theory allows an estimate of the hole's effec tive masses, yielding m(h perpendicular to)=(0.73+/-0.09)m(0) and m(h parallel to)=(0.17+/-0.03)m(0).