Electrical and photoelectrical characterization of an organic–inorganic heterojunction based on quinoline yellow dye

Abstract

An organic–inorganic contact was fabricated by forming a thin film of quinoline yellow dye (QY) on a p-Si wafer and evaporating Al metal on the film. The current–voltage (I–V) and capacitance–voltage (C–V) measurements of Al/QY/p-Si heterostructure were applied in dark and room temperature to calculate the characteristic parameters of diode like ideality factor, barrier height and series resistance. Ideality factor and barrier height values were found as 1.23 and 0.87eV from I–V data, respectively. The series resistance value of the device was determined as 1.8kΩ by using modified Norde function. The C–V measurements were carried out at different frequencies and it was seen that capacitance value decreased with increasing frequency. Interface state density distribution was calculated by means of I–V measurement. In addition the optical absorption of thin QY film on glass was measured and optical band gap of the film was found as 2.73eV. Furthermore, I–V measurements of Al/QY/p-Si/Al were taken under illumination between 40 and 100mW/cm2. It was observed that reverse bias current of the device increased with light intensity. Thus, the heterojunction had a strong response to the light and it can be suitable for electrical and optoelectronic applications like a photodiode.