Analysis of interface states of metal–insulator–semiconductor photodiode with n-type silicon by conductance technique

A metal–insulator–semiconductor photodiode (MIS-PD) as active layer with n-type silicon as interdigitated Schottky electrodes has been fabricated. The current–voltage characteristics, density of interface states and photovoltaic properties of the MIS-PD diode have been investigated. The diode has a metal–insulator–semiconductor configuration with ideality factor higher than unity. The electronic parameters (ideality factor, series resistance and barrier height) of the diode were found to be 1.94, 2.23 × 10⁴ Ω and 0.74, respectively. At voltages between 0.13 and 0.50 V, the charge transport mechanism of the diode is controlled by space charge-limited current mechanism. The interface state density of the diode was found to vary from 5.54 × 10¹² to 5.67 × 10¹² eV⁻¹ cm⁻² with bias voltage. The Au/SiO₂/n-Si/Al device shows a photovoltaic behavior with a maximum open circuit voltage V_oc of 97.7 mV and short-circuit current I_sc of 17.4 μA under lower illumination intensities. The obtained electronic parameters confirm that the Au/SiO₂/n-Si/Al diode is a MIS type photodiode.