Semiconductor Se-As System

DC conductivity has been measured as function of dopant concentration for Se-As glass containing 2-10 % As, doped with Cl or Br. It was established that concentration dependences of the conductivity have maxima for concentration of Cl or Br between 10−3 and 10−2 at %. The eect of halogen impurities on electroconductivity of Se-As glasses has been attributed to the change of relative concentrations of the charged defect centers (C−1; C 3) and to the occurrence of new Cl−; Br − centers associated with chlorine (bromine) atoms and the compensation of the eect of arsenic on the energy spectrum of electron states. The adding of bromine as an impurity to a Se-As system causes an intense increase a drift mobility of a hole by 2-3 orders of magnitude. This phenomenon and its mechanism, as explained by the eect halogens (bromine) have on local states thus controlling the charge transfer in Se-As, has been discussed in [1-3]. To obtain additional information about local states in the "forbidden band " of Se-As system with halogen (chlorine