IMPROVEMENT OF CHARGE-TRANSPORT IN SE-AS GLASSES BY DOPING WITH HALOGENS

Carrier drift mobility and dc conductivity have been measured as funct ions of dopant concentration for Se-As glasses containing 2-10% As, do ped with I, Br or Cl. It was established that concentration dependence s of the carrier drift mobility and conductivity have maxima for conce ntration of Cl or Br between 10 and 100 ppm. A significant increase in the carrier drift mobility was observed for doped samples. Depending upon the dopant species, the increase varied from one to four orders o f magnitude. The increase in dc conductivity, corresponding to the dri ft mobility maximum, was no more than one order of magnitude. The anal ysis of experimental data indicates that the effects observed can be a ttributed to changes in the concentration of charged intrinsic defects due to the influence of halogen impurities on these defects. The halo gen impurities are incorporated into the glasses in two ways: (1) as n egatively charged centres and (2) as chemically active atoms forming n eutral bonding configurations. In the latter case, a decrease in the c oncentrations of both negatively and positively charged intrinsic defe cts is observed.