Comparison of electrical and optical parameters of Au/n-Si and Ag/n-Si Schottky barrier photodiodes

This work represents the comparison between Au/n-Si and Ag/n-Si Schottky photodiode, with and without anti-reflection coating (LiF), and the air storage’s effect on their electrical and optical parameters. These Schottky photodiodes are used in different applications, such as solar monitoring, flame sensors and astronomy. The silicon Schottky photodiodes are realized by thermal deposition of a thin metal layer (gold (Au) and silver (Ag)) on n-type Si(1 1 1). Current–voltage (I–V) and capacitance– voltage (C–V) measurements are used to determine the ideality factor (n) with a value in the range of 1.1–1.3 and barrier height in the range of 0.85–0.93 eV. Determination of the optical characteristics such as quantum efficiency (QE) has been performed and the results show that the photodiode structure 250 nm LiF/15 nm Au/n-Si gives a quantum efficiency value of 22% at wavelength l ¼ 550 nm, whereas the value of 20% was obtained on the structure 250 nm LiF/15 nm Ag/n-Si. We mention that the values of quantum efficiency is affected by a sensible reduction of 25% after sixty (60) days air storage.