| Summary: | 碩士 === 國立中央大學 === 電機工程學系 === 104 === This study investigates the DC and transient performance of AlGaN/GaN high electron mobility transistors with different buffer layers, which were deposited on the low-resistivity Si (111) substrate. Based on the distinct buffer layers and i-GaN layer, we investigated the device breakdown characteristics and current collapse phenomenan. The main targets of this thesis is to analyze the device performance that correlated to the quality of buffer layers.
For the evaluation of the epitaxial layer’s quality, photoluminescence(PL) spectroscopy was used to study the YL/BE ratio that corresponds to different buffer layers, followed by the secondary ion mass spectroscopy and XRD measurement.
The epitaxial layers with lower YL/BE ratio, higher XRD FWHM, and lower Carbon concentration can result in high horizontal and vertical material breakdown and device breakdown voltages. In order to suppress the gate leakage current, the devices with MIS structure has been fabricated and the gate leakage characteristic were improved.
In this study, the transient measurements to analyze the performance of schottky and MIS HEMTs have been carried out. According to the experiments, the results indicate the epilayers with low YL/BE ratio, higher XRD FWHM, and lower Carbon concentration have significiently suppressed the current collapse effect when the devices were operated at high stress and high electric field.
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