Long-Living Excited State of the Te Donor in GaP

Abstract

The kinetics and temperature dependences (5 to 50 K) of the extrinsic photoconductivity (PC) in microwave (MCW) and DC electric fields in GaP doped with Te ( 2 × 1017 cm−3) have been studied. A slow relaxation (≈︂10−2 s) of MCW PC, in contrast to a fast DC PC relaxation was observed at 5 K. The steady-state MCW PC exceeded the DC PC by 2 to 3 orders of magnitude 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 observed. In the range 45 to 90 meV it increased, but decreased in the higher photon energy range. The obtained results are explained by accumulation of nonequilibrium electrons in the long-living excited state 1S(Γ3) of the Te donor in GaP.