抄録
The photocurrent multiplication due to impact ionization was observed in the a-Si : H/a-SiC : H staircase photodiode. On the staircase photodiode with one band offset, the photocurrent was multiplied double and was saturated. It was confirmed that almost all electrons were multiplied after they crossed the band offset. On the staircase photodiode with 3 band offsets, the saturated multiplication gain of about 6 was also obtained. The gamma values of the photocurrent characteristics were 1.0 indicating that there were no excess carriers entering from the electrode and no interband tunneling affected on photo-induced current. These results suggested that the impact-ionization at each conduction band stop due to the conduction-band discontinuity may be the dominant mechanism of the photocurrent multiplication.
