Impurity band conduction and negative magnetoresistance in p-ZnSnAs2 thin films

The previously reported transport properties data of the undoped ZnSnAs(2) grown on semi-insulating InP substrates by molecular beam epitaxy (MBE) have been reviewed and analysed. We have found out that the temperature dependence of Hail coefficient and resistivity c an be well explained by the impurity band model proposed by Isomura and Tomioka. By using the said model, we were able to resolve the experimentally obtained carrier concentration p(exp) and rnobility mu(exp) into valence band carrier concentration p(v) with mobility mu(v) and acceptor band carrier concentration p(a) with mobility mu(a). The computed apparent values p(app) and mu(app) are in good agreement with p(exp) and mu(exp), respectively. To support the validity of the model, we also have confirmed the presence at low temperatures of negative magnetoresistance expected if impurity band conduction is predominant.