Vapour transport grown photosensitive GeO2 thin film

Abstract

GeO2 thin film (TF) was fabricated by vapour deposition technique in a two zone horizontal quartz tube. Field emission-scanning electron microscopy showed the formation of 200 nm TF on the Si (100) substrate. The X-ray diffraction depicted the presence of the polycrystalline GeO2 TF. The UV–vis absorption spectrum showed humps at 3.1 eV, 4.0 eV and 5.4 eV. The band anticrossing (BAC) model is modified using the Urbach equation to understand the different transitions in the optical absorption spectrum. We have theoretically calculated the relative refractive index (r.i.) (nr) of the GeO2 as 1.8. The temperature dependent current (I)–voltage (V) characteristics and photocurrent of the Au/GeO2/p-Si Schottky device predicted the tunnelling of the carriers, presence of oxygen defects at the junction. The device’s temporal response indicated good photosensitivity at all temperatures and a significant increase in photocurrent was obtained as the temperature increased from 303 K to 403 K.