Structural and electrical characterization of photodetectors based on III-V nitrides
| dc.contributor.author | Lee, Yan Cheung | |
| dc.date.accessioned | 2016-10-31T02:19:05Z | |
| dc.date.available | 2016-10-31T02:19:05Z | |
| dc.date.issued | 2006-02 | |
| dc.description.abstract | This project is a study about the structural and electrical characterization of photodetectors based on III-V nitrides wide band gap semiconductors, namely gallium nitride (GaN) and aluminium gallium nitride (AlxGal-xN). The initial investigation includes the studies of metal-semiconductor-metal (MSM) photodetectors (photodiodes) which are based on low growth temperature amorphous and microcrystalline GaN grown on silicon (Si) substrates. Due to their smaller band gap, these photodiodes will not be totally visible blind in terms of UV photodetection applications. As a comparison, the microcrystalline GaN may promise a better prospect in UV detector application due to its similarity to normal high temperature grown GaN properties where the improvements that still need to be done could be the crystalline quality, the device dimension, and the introduction of a buffer layer between the Si and the GaN layer. The low dark current level of the amorphous GaN based photodiode also indicate a large dark resistance, where this behaviour is often desirable for photodetector application. However, a low reverse breakdown voltage at 4.3V of the amorphous photodiode is undesirable, thus preventing it from high power application. In addition, the low mobility nature of the amorphous GaN based photodetector will pose a threat to the speed of response, where the optimization that can be done on the device is yet to be discovered. As for the high temperature grown or normal single crystalline III-V nitrides based photodetectors, thermal annealing treatment will enhance the electrical properties of the devices but it is also a critical process to the stability of the contact structures. Here, the introduction of cryogenic quenching treatment right after thermal annealing treatment has produced a better device quality in terms of its electrical and structural properties when compared to the annealing only treatment to the device. Overall, the improvement in the dark current characteristics (dark current reduction) or the Schottky contact properties can be achieved significantly through high temperature annealing treatment, i.e. at about 600- 700°C for nickel (Ni) Schottky based III-V nitrides MSM photodiodes. As for Ni AIGaN Schottky diodes, the optimized temperature for the lowest leakage current (highest Schottky barrier height) can be achieved at 40QoC. For all the studies, cryogenic quenching treatment right after thermal annealing treatment is highly recommended to yield better results. Further annealing treatment with cryogenic quenching treatment of GaN MSM photodiodes have been studied briefly, and it has been found useful in further reducing the dark current level of the devices. | en_US |
| dc.identifier.uri | http://hdl.handle.net/123456789/2924 | |
| dc.subject | The structural and electrical characterization of photodetectors | en_US |
| dc.subject | based on III-V nitrides wide band gap semiconductors | en_US |
| dc.title | Structural and electrical characterization of photodetectors based on III-V nitrides | en_US |
| dc.type | Thesis | en_US |
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