All Transparent Metal Oxide Ultraviolet Photodetector

• Published in: Advanced electronic materials Vol. 1; no. 11
• Main Authors: Patel, Malkeshkumar, Kim, Hong‐Sik, Kim, Joondong
• Format: Journal Article
• Language: English
• Published: 01.11.2015
• Subjects: heterojunction devices; Mott–Schottky analyses; n‐ZnO; p‐NiO; transparent photodetectors
• ISSN: 2199-160X; 2199-160X
• DOI: 10.1002/aelm.201500232

A high‐performing UV photodetector that uses large energy bandgap materials of p‐type NiO and n‐type ZnO without an opaque metal electrode is reported. A quality heterojunction is formed by large‐area applicable sputtering deposition method that has an extremely low saturation current density of 0.1 μA cm−2. This abrupt p‐NiO/n‐ZnO heterojunction device is visible‐light transparent and shows the fastest photoresponse time of 24 ms among NiO‐based UV photodetectors, along with the highest responsivity (3.85 A W−1) and excellent detectivity (9.6 × 1013 Jones) properties. Structural, physical, optical, and electrical properties of nanocrystalline NiO are systematically investigated. Mott–Schottky analyses are applied to develop the interface of NiO and ZnO by establishing energy diagrams. Defects existing inside the nanocrystalline NiO film enhance the UV detection performance by defect‐assisted carrier transportation. The results provide a solid scheme of manipulation of NiO defects for functional photoelectric device applications. An all transparent photodetector is developed without metal electrodes. Visible light passes through the wide bandgap material NiO/ZnO interface to ensure high transparency. Meanwhile, long‐wavelength UV light is spontaneously absorbed to show the remarkable UV detection features with the fast photoresponse time. This approach provides the possibility for using wide bandgap materials in functional photoelectric applications.