A Highly Sensitive Heterojunction Photodetector for UV Application

Abstract

ZnO is considered as the most eminent semiconductors in the metal-oxide family because of its supreme properties which tempt many researcher groups to use this material for UV detection applications. In the earlier days, ZnSe and GaN based technologies create remarkable advance in the blue and UV LEDs and injection laser. Undoubtedly, GaN is considered to be the suitable candidate for optoelectronic devices fabrication.The effectiveness of photodetector is measured in terms of responsivity. The responsivity of n-ZnO/p-GaN is 0.678 mA/W at zero bias condition was reported, which can be improved by adding an intrinsic layer in between ZnO and GaN. At zero bias voltage, the peak responsivity of n-ZnO/i-ZnO/p-GaN heterojunction photodetector was 138.9 mA/W at 362 nm under the front illumination condition. This responsivity is still lower for various sensing and military applications. The responsivity of n-ZnO/i-ZnO/p-GaN heterojunction photodetector can be further improved by adding a SiO2 layer in between p-GaN and i-ZnO. The insertion of SiO2 layer reduces the visible response and boost the UV response. It is very important in many application such as whenever it is desirable to detect UV in visible and IR background. The n-Zno/i-ZnO/SiO2/p-GaN is a perfect structure for solar blind detector. By adding SiO2 layer the responsivity can be improved to 172.7 mA/W at 362 nm. This analysis is done by using TCAD tool.