Effects of gold-induced crystallization process on the structural and electrical properties of germanium thin films

Abstract

Gold-induced (Au-) crystallization of amorphous germanium (-Ge) thin films was investigated by depositing Ge on aluminum-doped zinc oxide and glass substrates through electron beam evaporation at room temperature. The influence of the postannealing temperatures on the structural properties of the Ge thin films was investigated by employing Raman spectra, X-ray diffraction, and scanning electron microscopy. The Raman and X-ray diffraction results indicated that the Au-induced crystallization of the Ge films yielded crystallization at temperature as low as 300 degrees C for 1hour. The amount of crystallization fraction and the film quality were improved with increasing the postannealing temperatures. The scanning electron microscopy images show that Au clusters are found on the front surface of the Ge films after the films were annealed at 500 degrees C for 1hour. This suggests that Au atoms move toward the surface of Ge film during annealing. The effects of annealing temperatures on the electrical conductivity of Ge films were investigated through current-voltage measurements. The room temperature conductivity was estimated as 0.54 and 0.73Scm(-1) for annealed samples grown on aluminum-doped zinc oxide and glass substrates, respectively. These findings could be very useful to realize inexpensive Ge-based electronic and photovoltaic applications.