Effects of annealing temperature on a ZnO thin film-based ultraviolet photodetector

Abstract

In this paper, the effects of annealing temperature on the performance of a ZnO thin film-based Metal-Semiconductor-Metal (MSM) type ultraviolet (UV) photodetector is reported. ZnO thin films were grown on a glass substrate using the Pulsed Filtered Cathodic Vacuum Arc Deposition (PFCVAD) technique at room temperature and after the deposition process the samples were annealed at 400, 450 and 550 °C in air condition to investigate the annealing effect on the structural, electrical, and optical properties of the photodetector. ZnO thin films which have grains in nanometer range has an increasing in the diameter of grains from 10.5 to 18.3 nm as a function of annealing temperature results in a red shift in the cut-off wavelength of the photodetector from 3.25 eV (381 nm) to 3.23 eV (383 nm). It is demonstrated that the sensitivity and the speed (rise/fall times) of the ZnO thin film based MSM photodetectors enhances with increasing post growth annealing temperature of ZnO thin film due to the increase in the absorption coefficient and the decrease of the total area of the grain boundaries due to the larger grain sizes formation in ZnO thin films with increasing thermal annealing temperature.

SWCNT-Si photodetector with voltage-dependent active surface

“…Photodetectors are our society's most used technological devices, with applications in day-life, medical, military, and research fields [1][2][3][4]. They can be realized using different materials or structures [5][6][7][8][9] but the oldest and best-understood photonic devices, with commercial products that can operate in the range from 300 to 900 nm, are the silicon photodetectors [10]. Despite their advanced technology, different intrinsic problems, such for example, the low absorption in the ultraviolet (UV) and infrared (IR) regions, still limit their possible applications.…”