Low-frequency noise properties of MgZnO nanorod ultraviolet photodetectors with and without UV illumination

Low-frequency current noise measurements were performed on Mg-doped ZnO (MZO) nanorod photodetectors (PD), and 1/f noise was observed in both dark and under ultraviolet (UV) illumination. Results show that the average length and diameter of the nanorods were 609 nm and approximately 50 nm, respectively. The X-ray diffraction spectrum showed that the Mg-doped ZnO nanorods had a wurtzite hexagonal sturcture. The photoelectric properties of the nanorods were stable under UV illumination. The resulting Mg-doped ZnO nanorods had excellent potential for UV photodetector applications. Mg-doped ZnO nanorod UV photodetectors had a high UV-to-visible ratio and a fast rise/fall time. The dynamic response of the Mg-doped ZnO nanorod photodetector was stable and reproducible with an on/off current contrast ratio of approximately 4 × 103. The UV-to-visible rejection ratio of the sample was approximately 400 when biased at 1 V, and the fabricated UV photodetector was visible-blind with a sharp cutoff at 350 nm. The low-frequency noise spectra obtained from the UV photodetector were caused by the 1/f noise. The noise-equivalent power (NEP) and normalized detectivity (D*) of the Mg-doped ZnO nanorod PD were 3.35 × 10−10 W and 1.49 × 108 cm Hz0.5 W−1, respectively. Under UV illumination, the NEP and D* were 1.8 × 10−6 W and 2.7 × 106 cm Hz0.5 W−1, respectively.