The annealing effect on Au/a-Si:H/a-Si:H(n-type)/Cr Schottky diodes prepared by an RF magnetron sputtering technique
The annealing effect on Au/a-Si:H/a-Si:H(n-type)/Cr-type Schottky diodes has been investigated. Thin films of amorphous silicon were prepared by an RF magnetron sputtering technique on a glass substrate with Cr contacts and then gold electrodes (area=7.85*10-3 cm2) were fixed under a vacuum of 10-5 Torr. Measured current-voltage characteristics, before and after annealing at about 70-200 degrees C, show significant differences and therefore it has been concluded that the rectification ratio increases and the ideality factor decreases with increasing annealing temperature. The barrier height phi Bn and density of surface states Ds were found to be phi Bn=0.641 and 0.726 eV and Ds=3.47*1013 and 3.30*1013 states cm-2 eV-1 employing Crowell-Sze's and Cowley-Sze's theories respectively. The changes in the current-voltage characteristics were explained by means of surface states at the metal/semiconductor interface.