ELECTRICAL-PROPERTIES OF EVAPORATED POLYCRYSTALLINE GE THIN-FILMS

Electrical properties of Ge thin films evaporated on Si3N4 CVD-coated Si substrate were improved by introducing a heat treatment after the d eposition of Ge films. Evaporation conditions were optimized by changi ng the substrate temperature and deposition rate, and then, heat treat ment was performed. At substrate temperatures during the evaporation l ower than 300 degrees C and higher than 400 degrees C, deposited films were amorphous and polycrystalline, respectively. At substrate temper atures lower than 400 degrees C, Ge films were evaporated without degr ading the surface roughness. The Hall mobility of films evaporated at room temperature increased with increasing the substrate and heating t emperature and showed about 400 cm(2) V-1 s(-1) for the hole concentra tion of 4x10(17) cm(-3) at the heating temperature of 900 degrees C. T his value was almost comparable to that of p-type Ge single crystal. ( C) 1997 Published by Elsevier Science S.A.