The surface morphology properties and respond illumination impact of ZnO/n-Si photodiode by prepared atomic layer deposition technique

Abstract

The ZnO layer onto n-Si has been formed by atomic layer deposition technique. A final film thickness of 10 nm has been obtained by the resulting ZnO film growth rate of about 1.45 Å per cycle. The crystal structures of the ZnO layer were acquired by X-ray diffractometer (XRD) and it could be seen ZnO peaks from XRD patterns. The surface of ZnO thin film onto the n-Si could be seen with Atomic Force Microscopy (AFM) images and it were obtained homogenous and smooth surface. The I-V measurements were performed −2V to +2 V under dark and light, C-V measurements were performed changing 10 kHz to 2 MHz frequency and −2 V to +2 V bias voltage at room temperature. The device has the saturation current value of 8.99 × 10−9A. The values of ideality factor (n) and the barrier height (Фb) have been found to be 2.49 and 0.77 eV by using the thermionic emission theory, respectively. In addition, the barrier height Фband the series resistance (Rs) have been also acquired from Cheung's functions. The photovoltaic parameters of device; short circuit current (Isc), open circuit voltage (Voc), fill factor (FF) and conversion efficiency (ƞ) were taken as 342 mV, 34.7 μA, 32% and 0.48% under 100 mW/cm2light intensity, respectively. The C–V and G–V plots of device almost have peaks in all frequencies except for 2 MHz frequency. The device also behaved like memristor at 500 kHz dual C–V measurements under dark and light but has not wide memory window. It has been concluded that the device can be used as photodiode at room temperature because of small saturation current and good rectifying behavior and it may be improved photovoltaic, capacitor and memristor properties of Au/ZnO/n-Si device in the future. © 2016 Elsevier B.V.