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

Abstract

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 50nm, 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 1V, and the fabricated UV photodetector was visible-blind with a sharp cutoff at 350nm. 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 3.35×10−10W and 1.49×108 cmHz0.5W−1, respectively. Under UV illumination, the NEP and D* were 1.8×10−6 W and 2.7×106 cmHz0.5W−1, respectively.