Electrical properties of GaSe doped with Er

Measurements of the Hall effect and Er-related luminescence were made on Er-doped GaSe. Deep-level transient spectroscopy (DLTS) was also performed. Hall measurements show that hole concentrations of 0.2%, 0.5%, and 1% Er-doped GaSe samples are 1.5×1017–6×1017 cm−3 at room temperature, and that the mobility of these holes is in the range 22–34 cm2/V s. The temperature dependence of the hole concentration is explained using the two-acceptor model, in which one acceptor level is at around 65 meV above the valence band and the other one is at ∼158 meV. The DLTS measurements yield similar results. Furthermore, the shallow acceptor impurities contribute free hole carriers and act as radiative centers; the deep acceptor impurities are nonradiative centers, which are responsible for the quenching behavior of Er-related luminescence. The temperature dependence of the hole mobility can be understood as the combined scatterings of homopolar optical phonons and ionized impurities.