Improvement of Responsivity of Antenna-Coupled Warm Carrier Device Using Polycrystalline Ge Thin Films

Abstract

Electrical properties of Ge thin films evaporated on Si3N4 substrates were improved by introducing a heat treatment after the deposition. The Hall mobility of the deposited films increased with increasing heat-treatment temperature and was 280 cm2/V·s for a hole concentration of 6×1017 cm-3 at a heat-treatment temperature of 900° C. This value of the Hall mobility was about three times larger than that obtained for Ge films without heat treatment. A point-contact warm carrier device was also fabricated using evaporated Ge film with heat treatment, and the detected voltage induced by CO2 laser radiation was measured. The fabricated device operated as an antenna-coupled device and the detected voltage was about ten times higher than that obtained using a device without heat treatment.