III-nitride direct bandgap semiconductors have attracted significant research interest due to their outstanding potential for modern optoelectronic and electronic applications. However, the high cost of III-nitride devices, along with low performance due to dislocation defects, remains an obstacle to their further improvement. In this dissertation, I present a significant enhancement of III-nitride devices based on emerging materials. A promising substrate, (-201)-oriented β-Ga2O3 with unique properties that combine high transparency and conductivity, is used for the first time in the development of high-quality vertical III-nitride devices, which can be cost-effective for large-scale production. In addition, hybridizing GaN with emerging materials, mainly perovskite, is shown to extend the functionality of III-nitride applications. As a part of this investigation, high-performance and high-responsivity fast perovskite/GaN-based UV-visible broadband photodetectors were developed.
State-of-the-art GaN epilayers grown on (-201)-oriented β-Ga2O3 using AlN and GaN buffer layers are discussed, and their high optical quality without using growth enhancement techniques is demonstrated. In particular, a low lattice mismatch (⁓4.7%) between GaN and the substrate results in a low density of dislocations ~4.8Å~107 cm−2. To demonstrates the effect of (-201)-oriented β-Ga2O3 substrate on the quality of III-nitride alloys, high-quality ternary alloy InxGa1−xN film is studied, followed by the growth of high quality InxGa1−xN/GaN single and multiple quantum wells (QWs). The optical characterization and carrier dynamics by photoluminescence (PL) and time-resolved PL measurements were subsequently performed. Lastly, to investigate the performance of a vertical emitting device based on InGaN/GaN multiple QWs grown on (-201)-oriented β-Ga2O3 substrate, high-efficiency vertical-injection emitting device is developed and extensively investigated. The conductive nature of the substrate developed as a part of this study yields better current and heat characteristics, while its transparency ensures high light extraction. The straightforward and direct growth process employed does not require a high-cost complex fabrication process.
Finally, a broadband photodetector composed of the emerging CH3NH3PbI3 perovskite with the p-GaN, is developed. The findings reported in this dissertation demonstrate the superior performance of CH3NH3PbI3/GaN photodetectors produced by simple and cost-effective solution processed spray-coating method. In particular, it is demonstrated that perovskite/GaN device can work as a self-powered photodetector.
| Identifer | oai:union.ndltd.org:kaust.edu.sa/oai:repository.kaust.edu.sa:10754/627382 |
| Date | 11 March 2018 |
| Creators | Mumthaz Muhammed, Mufasila |
| Contributors | Roqan, Iman S., Physical Science and Engineering (PSE) Division, Rothenberger, Alexander, He, Jr-Hau, Liu, Zhiqiang |
| Source Sets | King Abdullah University of Science and Technology |
| Language | English |
| Detected Language | English |
| Type | Dissertation |
| Rights | 2019-03-29, At the time of archiving, the student author of this dissertation opted to temporarily restrict access to it. The full text of this dissertation became available to the public after the expiration of the embargo on 2019-03-29. |
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