Wide band gap semiconductors such as ZnO are characterized by unique optoelectronic properties, which have led to numerous applications in the field of sensors and optoelectronics. These components are commonly fabricated on rigid substrates. However, the same synthesis method cannot be used to fabricate these components on flexible substrates. In this work, we present a method to fabricate metal−semiconductor−metal ultraviolet photodetectors with ZnO nanorods on flexible substrates. It is observed that the overall characteristics of the fabricated ZnO nanorod photodetector are greatly enhanced by doping with gallium (Ga). The nanorods are grown on a flexible substrate (poly(ethylene 2,6-naphthalate)) at a low temperature of 80 °C. The performance of Ga-doped ZnO nanorods (GZO) shows a significant improvement in electrical measurements compared to pure ZnO nanorods. The photocurrent-to-dark current ratios of both ZnO and GZO nanorod-based photodetectors are approximately 8.5 and 570.2 under a 1 V bias, respectively. The dark current and photocurrent are substantially improved by the addition of the Ga dopant. Transient response measurements indicated that the GZO nanorod photodetectors are stable and reproducible, and no change in the current−voltage characteristics is noted after multiple bending cycles. These results indicate that Ga-doping can improve the ZnO nanorod optical and electric characteristics; this proposed method is useful for device fabrication on low-melting-point substrates to produce flexible cost-effective devices.
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