Investigation of conduction kinetics in Al/CuInSe2 Schottky device utilizing impedance spectroscopy (IS) measurement and study of its photosensing behaviour

Abstract

Copper Indium Selenide (CuInSe2) has been synthesized by solvothermal synthesis method. The Schottky diode (SD) has been fabricated by using the material and the interface characteristics of Al/CuInSe2/ITO have been investigated with the help of ac impedance spectroscopy (IS) analysis (under dark condition) and dc current-voltage (I–V) measurements (under both dark and photo condition). IS is a very important and powerful technique to investigate and analyze the impedance at the boundary regions of SDs. Ac impedance spectra of Al/CuInSe2 SD have been recorded in the wide range of frequency from 40 Hz to 20 MHz during dc bias scanning from −0.5 V to 0.5 V under dark condition. From forward I–V characteristics, important parameters such as ideality factor (η), photosensitivity, barrier height (Φb), series resistance (RS) of SD were obtained under dark and photo condition. The photosensitivity of the Al/CuInSe2 SD was found to be 3.36. For better realization of charge transport phenomena through the MS junction, space charge limited current (SCLC) theory has been employed. The effective mobility of the carrier is evaluated in dark and photo condition as 0.42 × 10−3 m2V−1s−1 and 2.11 × 10−3 m2V−1s−1 respectively. It has been observed that the mobility is improved 5 times under illumination compared to the dark condition.