| Summary: | 碩士 === 國立成功大學 === 微電子工程研究所碩博士班 === 95 === In this thesis, we adopt the surface treatment to improve the performance of the GaN-based MSM photodetectors with thin Ni/Au film as Schottky contacts and investigated the characteristics of these devices.
Among the different kinds of solutions for surface treatment, the sample which has undergone boiled alcohol-based KOH surface treatment shows the most effect removal of thin native oxide and the much significant reduction of surface states. Besides, the internal gain effect can be efficiently suppressed by the anneal treatment under O2 ambient at 550℃. Such great improvement can be attributed to the formation of p-type NiO. It is also found that the rejection ratio (360/450nm) in response is up to 1.078E4 for 550℃ annealed MSM photodetector fabricated on the boiled alcohol-based KOH surface treated sample with a 5V applied bias.
Sometimes, it is necessary to fabricate these GaN-based optoelectronic devices with the inductively coupled plasma (ICP) dry etching method. In order to recover these damages, we adopt the method of surface treatment to improve the performances of the devices. After the surface treatment, the anneal treatment can more significantly decrease the numbers of surface states and the traps-assisted tunneling effect will be effectively suppressed, too. The rejection ratio is about 1.421E3 for the device annealed after boiled alcohol-based KOH surface treatment. Besides, the GaN-based MIS UV detectors are also fabricated. The SiO2 insulator was deposited by means of plasma enhanced chemical vapor deposition (PECVD). It is found that the devices performance have been improved by inserting the SiO2 layer. The rejection ratio (360/450nm MIS) can be improved from 6.92 to 16.88 for the sample ICP damaged and the sample treated by boiled alcohol-based KOH, respectively.
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