Effect of illumination intensity on the characteristics of Co/Congo Red/p-Si/Al hybrid photodiode

Abstract

In this study, Congo Red (CR) organic dye interlayer was covered by sping coating on p-Si semiconductor wafer and Co/CR/p-Si/Al photodiode was fabricated. The surface morphology of CR film was characterized by SEM measurement. Current–voltage (I–V) characteristics of the photodiode were obtained under different illumination intensities. The electrical, sensitivity, and photoresponsivity properties of Co/CR/p-Si/Al photodiode were investigated using the current–voltage and capacitance–voltage measurements. While the calculated barrier height (Φb) and ideality factor (n) were 0.58 eV and 1.52 under the dark, these values were 0.55 eV and 1.62 under the 400 mW cm−2, respectively. The exponent of photocurrent was found to be 1.10. This value indicates that the photodiode exhibited a linear photocurrent variation with power of the light. It was found that the interface-state intensity of the photodiode decreased from 1.64 × 1015 to 8 × 1012 eV−1 cm−2 under the 400 mW cm−2 light intensity. The rectification rate of photodiode (RR) of the photodiode was found under the dark and illumination. All experimental results indicate that the photodiode exhibits a photoconducting characteristic.