Influence of N2 flow rate on UV photodetection properties of sputtered p-ZnO/n–Si heterojuctions

Abstract

Al–N codoped ZnO heterojunction diodes were grown on n–Si (100) substrates using radio frequency (RF) magnetron sputtering with different flow rates of N2 reactive gas (5–18 sccm). X-ray diffraction results revealed that codoped ZnO thin films have wurtzite structure with crystallite size 25–31 nm. Scanning electron micrographs revealed that all thin film samples have agglomerated flakes type surface morphology. The optical band-gap determined using UV–Vis transmission spectra was found increased with increasing the flow rate of N2. The current-voltage (I–V) measurements were performed in dark and illumination condition using UV light (wavelength 365 nm) for photodetection application. The high stability and fast switching UV photoresponse behaviour was obtained for p-ZnO/n–Si. The maximum responsivity 0.16 A/W was obtained at 3.2 mW/cm2 illumination of the UV light (365 nm) at 5 V bias voltage.