Noise Properties of Low-Temperature-Grown Co-Doped ZnO Nanorods as Ultraviolet Photodetectors

Abstract

The growth of vertically aligned cobalt-doped ZnO (Co-ZnO) nanorods on a glass substrate using a low-temperature hydrothermal method is reported. A Co-ZnO nanorod metal-semiconductor-metal ultraviolet photodetector (PD) was also fabricated. The ratio of UV-to-visible rejection of the fabricated PD was approximately 11700 when biased at 1 V with a sharp cutoff at 380 nm. With an incident light wavelength of 380 nm and an applied bias of 1 V, the measured responsivity of the PD was found to be 19.8 A/W. Furthermore, the dark noise equivalent power (NEP) and photo NEP of the fabricated Co-ZnO nanorod MSM PD were 1.3 × 10 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">-13</sup> and 1.8 × 10 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">-11</sup> W at the corresponding dark detectivities (D*) and photo D* of 1.1 × 10 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">14</sup> and 7.3 × 10 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">11</sup> cm · Hz <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">0.5</sup> · W <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">-1</sup> , respectively.