For III-nitride wide-bandgap materials, the lack of efficient p-type wide bandgap semiconductors limits the full potential of group-III nitride-based optoelectronic devices. Conventional wide bandgap p-type materials consisting of magnesium-doped gallium nitride (GaN:Mg) and magnesium-doped aluminum gallium nitride (AlGaN:Mg) typically exhibit low hole carrier concentrations of <1018 cm-3 . Hence, I used different wide bandgap inorganic p-type materials as a promising solution, e.g., copper thiocyanate (CuSCN). CuSCN has multiple attractive properties that hold potential for applications in III-nitride materials. For example, its energy band gap is up to 3.9 e.V and its electron effective mass is higher than its hole effective mass. These two key features make CuSCN a potential wide bandgap p-type material for III-nitride systems. By exposing CuSCN to chlorine, Cl2-infused CuSCN thin film achieves a hole concentration up to 3 × 1018 cm-3 and maintains its visible-light-blind optical properties. Based on these desirable features, p CuSCN/n-GaN heterojunction ultraviolet photodetectors, as well as the p-CuSCN and n GaN interface, were fabricated to investigate the potential applications of p-CuSCN in III nitride devices. Moreover, p-CuSCN also benefits the corresponding organic solar cells; p CuSCN-based organic solar cells perform better in power conversion efficiency and stability tests under various conditions than intrinsic CuSCN-based organic solar cells. This work on p-CuSCN not only paves the way for new III-nitride semiconductor devices, but may also potentially enable the development of organic devices with better performance and longer lifetime.
To explore the potential of transition metal oxides in UV photodetectors, NiO was selected to proceed with device fabrication because of its wider energy bandgap and lower hole effective mass than other transition metal oxides. Since single crystal quality is required to maintain its visible-light-blind optical property, brand-new templates were invented to grow single-crystal NiO thin films, TiN/MgO, and TiN/Si. Use of TiN thin film between NiO and the substrates provides a good back-side metal contact for NiO-based semiconductor devices. Several tools were employed to ascertain the single-crystal quality of as-grown NiO thin films on TiN/MgO and TiN/Si. I demonstrate NiO/TiN/MgO and NiO/TiN/Si bilayer structures may pave the way towards better NiO-based ultraviolet optoelectronic devices.
| Identifer | oai:union.ndltd.org:kaust.edu.sa/oai:repository.kaust.edu.sa:10754/673773 |
| Date | 11 1900 |
| Creators | Liang, Jian Wei |
| Contributors | Ooi, Boon S., Computer, Electrical and Mathematical Science and Engineering (CEMSE) Division, Ohkawa, Kazuhiro, Schwingenschlögl, Udo, Fu, Lan |
| Source Sets | King Abdullah University of Science and Technology |
| Language | English |
| Detected Language | English |
| Type | Dissertation |
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