Semiconductor-metal transition in liquid As-Te mixtures

EXAFS, conductivity and Hall coefficient measurements have been carried out for liquid As-Te mixtures. EXAFS analysis reveals the presence of chemical disorder marked by the existence of homopolar As-As and Te-Te pairs. At hi gh temperature around 500 degrees C the network structure composed of three fold coordinated As atoms and twofold coordinated Te atoms is transformed i nto the twofold chain structure. The network-chain transformation is accomp anied by the gradual semiconductor to metal transition which is demonstrate d by the results for conductivity and Hall coefficient. The microscopic ori gin of the semiconductor to metal transition is discussed in connection wit h the structural modification.