Solar light performances of n-ZnO nanorods/p-Si-based photodetectors under high illumination intensity

Abstract

We present ZnO nanorod/ZnO thin film structures synthesized at different molarities and growth times using a hydrothermal method, exhibiting uniquely solar sensing characteristics. ZnO thin film was deposited on p-Si(100) substrate by using RF sputter. ZnO nanorods with different molarities (10 and 20 mM) and growth times (2, 3, and 4 h) were fabricated at 90 °C by using the hydrothermal method on the n-ZnO/p-Si. The surface texture was also examined by scanning electron microscopy. The diameter of ZnO NRs was in the range of 62–119 nm. The current–time measurements were done under solar light illumination intensity (50 and 100 mW/cm2) and forward bias voltage (1, 5, and 10 V). Decay time (τd), rise time (τr), detectivity (D*), responsivity (R), and sensitivity (S) parameters were calculated. Samples produced at 2 h and 3 h in 10 mM solution performed best due to low τd, τr, and high D*, R, S. Especially, the S for the PD102 changed from 4.24 to 11.8, while it was in the range of 0.41–7.33 for the PD103. The R was 5.81 AW−1 in PD102 and 1.19 AW−1 in PD103. The D* was 109–1011 cmHz1/2/W in PD102 and 1010–1011 cmHz1/2/W in PD103 at ± 6 V.