THERMOELECTRIC VOLTAGES FROM SI CLEAVAGES

We have detected voltages between ohmic electrodes on Si wafers when a cleavage occurs at one of the contacts. Samples were measured at room temperature (RT) in air and under liquid nitrogen. The detected signa l are positive for p-type and negative for n-type samples. show a temp oral decay profile consistent with cooling, and are consistent with cl eavage heat generation causing a thermoelectric effect. The signals pe ak after the system response time of 0.1 ms, are of average magnitude 59 mu V at RT, and at 78 K are 103 mu V, consistent with the increased thermopower at low temperatures. The data, considering the large cool ing by the bulk and metallic contact, indicate that significant elevat ed temperatures occur at the cleavage surface. This can affect surface structures and properties. (C) 1997 Elsevier Science B.V.