Long-living excited state of the Te donor in GaP

The kinetics and temperature dependences (5 to 50 K) of the extrinsic photo conductivity (PC) in microwave (MCW) and DC electric fields in GaP doped wi th Te (2 x 10(17) cm(-1)) have been studied. A slow relaxation (approximate to 10(-2) s) of MCW PC, in contrast to a fast DC PC relaxation was observe d at 5 It. The steady-state MCW PC exceeded the DC PC by 2 to 3 orders of m agnitude at 5 to 16 K, and dropped by subsequent increase of temperature to 35 K. In the same temperature range a slow relaxation of absorption of the room-temperature background radiation, induced by GaP excitation was obser ved. In the range 45 to 90 meV it increased, but decreased in the higher ph oton energy range. The obtained results are explained by accumulation of no nequilibrium electrons in the long-living excited state 1S(Gamma 3) of the Te donor in GaP.