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 deposition of Ge films. Evaporation conditions were optimized by changing the substrate temperature and deposition rate, and then, heat treatment was performed. At substrate temperatures during the evaporation lower than 300 degrees C and higher than 400 degrees C, deposited films were amorphous and polycrystalline, respectively. At substrate temperatures lower than 400 degrees C, Ge films were evaporated without degrading the surface roughness. The Hall mobility of films evaporated at room temperature increased with increasing the substrate and heating temperature and showed about 400 cm(2) V-1 s(-1) for the hole concentration of 4x10(17) cm(-3) at the heating temperature of 900 degrees C. This value was almost comparable to that of p-type Ge single crystal. (C) 1997 Published by Elsevier Science S.A.