Comparative investigation of Ga- and Sn-doped ZnO nanowires/p-Si heterojunctions for UV-photo sensing

Vertically oriented undoped, Ga-doped and Sn-doped ZnO nanowires are grown by using novel double step chemical bath deposition (CBD) technique. The nanowire morphology, crystallite quality, energy bandgap, and UV-visible absorption properties are investigated by employing FESEM, XRD and UV-vis measurements. Comparative photoresponse of the ZnO nanowire/p-Si heterojunction photodiodes is studied by measuring the photo-to-dark current ratios, self-powered photo-switching behavior and intensity-dependant photocurrent at zero applied bias. Ga-doped ZnO nanowires/p-Si heterojunction photodiode exhibits relatively higher photocurrent while the Sn-doped devices show faster photoswitching operation. An excellent photoresponse with the linear dependency of photocurrent on the incident UV-intensity has been observed in the Sn-doped photodiodes.