The Effect of Ga Doping Concentration on the Low-Frequency Noise Characteristics and Photoresponse Properties of ZnO Nanorods-Based UV Photodetectors

This study investigates the control of Ga doping in ZnO nanorods (NRs) grown on an amorphous ZnO-seeded glass substrate through hydrothermal method. ZnO was doped with various Ga concentrations (0.25, 0.5, and 1 mM). The average lengths of the resulting NRs were approximately 2.36, 1, and 1.5 μm, respectively, and the average diameters were 123, 78, and 117 nm, respectively. In addition, Ga-doped ZnO (GZO) NR-based ultraviolet photodetectors (PDs) with a sharp cutoff at 370 nm were fabricated. With an applied voltage of 1 V, different Ga precursor solution concentrations of 0.25, 0.5, and 1 mM yielded measured device responsitivities of 2.2 × 10^-2, 14.9, and 14.1 A/W, respectively. The Ga concentration can be used to control the responsivity of the fabricated PDs. Furthermore, the measured noise equivalent power of the PDs at 0.25, 0.5, and 1 mM were 1.06 × 10^-9, 3.13 × 10^-11, and 1.29 × 10^-10 W, respectively. The corresponding detectivities of the GZO NR PDs were measured at 1.24 × 10¹⁰, 4.21 × 10¹¹ W, and 1.01 × 10¹¹ cm·Hz^0.5·W^-1, respectively.