Low-Frequency Noise Spectra of Laterally Bridged ZnO Microrod-Based Photodetectors

The laterally bridged ZnO microrods grown from an Au electrode applied to metal-semiconductor-metal photodetector was fabricated. Interlaced ZnO microrods with approximate single-crystalline structure can be grown from Au electrode fingers. The dark-current was 5.00 × 10^-5 A with an applied voltage of 1 V. Highly dense lateral ZnO microrod-based photodetectors produce remarkable responsivity of 1.93 × 10⁵ A/W. Moreover, an extremely high internal photoconductive gain of 6.28 × 10⁵ exists in the fabricated photodetectors. For a given bandwidth of 10 kHz and 1 V applied bias, the noise equivalent power of photodetectors were estimated to be 1.86 × 10^-13 W, and correspond to normalized detectivity of 1.12 × 10¹² cm·Hz^0.5 W^-1. This result may be attributed to an internal photoconductive gain mechanism and high-density bridged ZnO microrods. Our approach provides a simple and seed-layer-free method to fabricate high-performance ultraviolet photodetectors.