Fabrication, temperature dependent current-voltage characteristics and photoresponse properties of Au/α-PbO2/p-Si/Al heterojunction photodiode

Thin film of lead dioxide, α-PbO2, has been grown by thermal evaporation technique on the single crystal of p-Si substrate and heterojunction photodiode, Au/α-PbO2/p-Si/Al, was fabricated. The current-voltage characteristics of the diode have been studied in the temperature ranged from 303 to 373 K and the voltage applied during measurements varied from −1 to 1.5 V. It was found from the (I-V) characteristics of the diode that the conduction mechanisms in the forward bias direction are controlled by the thermionic emission at bias potential ≤0.7 V followed by single trap space charge limited current (SCLC) conduction in the voltage range >0.7 V. The capacitance-voltage characteristics of the device were studied at room temperature in dark condition and it has been shown that the diode is abrupt junction. The carrier concentration on both sides of the depletion layer has been determined. Energy band diagram for α-PbO2/p-Si device was constructed. The device under illumination with light of intensity 20 W/m2 gives acceptable values of photoresponse parameters such as photosensitivity and photoconductivity. The presented photodiode parameters exhibit the typical photosensor applications with reproducibility phenomenon.