Impact of oxygen deficiency and shallow hole-traps on high-responsivity ZnO-based UV photodetectors

Abstract

In this study, zinc oxide (ZnO) films have been investigated as potential high-responsivity, low-cost ultraviolet (UV) detection materials for biomedical applications. Fabricated using radiofrequency (RF) sputtering and rapid thermal annealing (RTA), ZnO films exhibit a high band gap energy (∼3.25 eV) and minimal oxygen deficiency after RTA at 400 °C. These properties significantly influence the UV detection capabilities of the films. Metal-semiconductor-metal (MSM) type UV photodetectors (PDs) constructed from these films demonstrate a high responsivity for UV-A/B detection (∼3.15 kA/W at 340 nm), which is associated with shallow hole-related traps caused by the oxygen deficiency. By applying the Arrhenius equation, two primary shallow hole traps at 37 and 241 meV were identified. The findings of this study can contribute to the development of ZnO-based UV detectors and provide insights into their temperature-dependent properties and persistent photoconductivity effects.