THE EFFECT OF HEAT-TREATMENT ON THE ELECTRICAL-POWER FACTOR OF HIGH-TEMPERATURE ANNEALED N-SIGE GAP THERMOELECTRIC ALLOYS

The long-term stability of the electrical power factor of high-tempera ture annealed n-type SiGe/GaP alloys was investigated under device 'ho t side' operating temperatures. Experimental results indicate that the electrical conductivity decreases continuously with time while the Se ebeck coefficient increases continuously with time when the alloys are subjected to intermediate temperature heat treatment (973 K). However , when the samples are heat-treated at increasingly higher temperature s, the electrical conductivity passes through a minimum and then incre ases while the Seebeck coefficient reaches a maximum and then decrease s. The results are explained in terms of dopant precipitation and chan ges in carrier scattering mechanisms. Preliminary results suggest that the enhanced electrical power factor, which accompanies high-temperat ure annealing, decreases with time when the samples investigated were subjected to temperatures between about 1073 and 1273 K.