The current-voltage characteristics of n-InGaZnO/p-Si heterojunctions photodiode

Both the light and dark current-voltage (I-V) characteristics of n-InGaZnO/p-Si photodiodes (PD) fabricated by radio frequency magnetron sputtering of n-IGZO films on p-Si substrates at 25 degrees C, 200 degrees C and 400 degrees C have been studied. The dark I-V characteristic indicates the existence of negatively charged interface states at Si-InGaZn oxide interface layer (IL). A theoretical model with IL included is developed and it is found that this model explains the light I-V characteristics observed here well. According to our model, the unique behavior of these PDs is attributed to the impurity concentration of IGZO film and the low electron mobility and deficiency of conduction electrons at IL which causes electron accumulation at interface.