Effect of Ga and P dopants on the thermoelectric properties of n-type SiGe

The purpose of this study was to hot-press improved n-type Si/sub 80/Ge/sub 20//GaP samples directly (without any heat treatment) and to confirm that a Ga/P ratio less than one increases the solubility of P and, hence, improves the power factor and Z. One of the three sample (Ga/P=0.43) had an improvement in Z of about 20% between 400 and 1000 degrees C over that for standard SiGe. This demonstrates that improved samples can be pressed directly and that a Ga/P ratio less than one is necessary. The other two samples (Ga/P=0.33 and 0.50) and Z's equal to or less than that of standard SiGe but had a lower hot-pressing temperature than the improved sample.>