Optical and electrical characteristics of p -GaSe doped with Te

Measurements of the Hall-effect, photoluminescence (PL), and photocurrent (PC) have been made on Te-doped GaSe. The carrier transport for the Hall-effect measurement is dominated by the two acceptor levels at 0.08 and 0.02 eV above the valence band. The two acceptor levels have the same energy positions as the impurity levels in the PC spectra. By comparison with the results of GaSe grown with excess Se atoms, it was found that these acceptor levels are caused by the interstitial Te atoms. Moreover, the PC and PL spectra are dominated by the transition related to the indirect band and show the relaxation of the selection rule.