Electronic Conduction Mechanisms and Defects in Polycrystalline Antimony Selenide

A study of the electronic conduction mechanisms and electrically active defects in polycrystalline Sb2Se3 is presented. It is shown that for temperatures above 200 K, the electrical transport is dominated by thermal emission of free holes, ionized from shallow acceptors, over the intergrain potential barriers. In this temperature range, the temperature dependence of the mobility of holes, limited by the intergrain potential barriers, is the main contributor to the observed thermal activation energy of the conductivity of 485 meV. However, at lower temperatures, nearest-neighbor and Mott variable range hopping transport in the bulk of the grains turn into the dominant conduction mechanisms. Important parameters of the electronic structure of the Sb2Se3 thin film such as the average intergrain potential barrier height phi = 391 meV, the intergrain trap density N-t = 3.4 x 10(11 )cm(-2), the shallow acceptor ionization energy E-A0 = 124 meV, the acceptor density N-A = 1 x 10(17) cm(-3), the net donor density N-D = 1 x 8.3 x 10(16) cm(-3), and the compensation ratio kappa = 0, 79 were determined from the analysis of these measurements.