Electric Resistivity Measurements of Sb2Te3 and Ge2Sb2Te5 Melts Using Four-Terminal Method

In this work, we aim to determine the electric resistivities of liquid Sb2Te3 and Ge2Sb2Te5. Electric resistivities were measured using the four-terminal method. First, the electric resistivities of liquid Ga and Sn were measured to establish this method. Second, the electric resistivities of Sb2Te3 and Ge1.6Sb2.0Te5.0 were measured over temperature ranges between the respective melting temperatures of samples and 1020 K. The electric resistivity of Sb2Te3 has been determined to be 4.36 +/- 0.14 mu Omega m at 992 K. The uncertainty was determined on the basis of the guide to the expression of uncertainty in measurement. The electric resistivity of Ge1.6Sb2.0Te5.0 is smaller than that of Sb2Te3. It is also found that both resistivities decrease with an increase in temperature; which indicates that both liquid materials behave as a semiconductor. Therefore, the pseudogap model was applied to derive the electrical activation energies. (C) 2010 The Japan Society of Applied Physics