| dc.description.abstract | This paper focuses on the studys of the novel PNP-GaN gate HEMT. This structure adds a PN-GaN diode to the traditional p-GaN gate structure. The research includes new device design, Silvaco TCAD device characteristics simulation, device fabrication, and electrical measurement analysis. The device characteristics are compared between the new gate structure and the traditional p-type GaN gate structure.
Comparing with the p-GaN gate HEMT, the PNP-GaN gate HEMT has smaller gate leakage, which has decreased about 147 times at VGS = 10 V, VDS = 10 V. At this time, the ID and IG ratio of the PNP-GaN gate HEMT is still greater than 105. In terms of gate breakdown characteristics, the novel PNP-GaN gate HEMT has reached 19.8 V. Compared with the traditional p-GaN gate HEMT, the new gate structure can have a larger gate drive range. The 10-year life expectancy of the gate can also reach 10.5 V. The additional PN-GaN diode causes a voltage drop when the gate is positive bias. The threshold voltage of the device is therefore increased. The threshold voltage of the new PNP-GaN gate HEMT is 2.96 V. The additional voltage drop also makes Schottky diode has a lower electric field which increases the reliability and bias range of the gate. Due to the addition of PN-GaN, the input capacitance has a smaller gate capacitance than the general p-GaN gate HEMT.
In addition, the use of gate insulator to further increase the VTH of the device and reduce the gate leakage current. The proposed new MIS PNP-GaN gate HEMT was also fabricated. The device initially demonstrate the increased VTH and low gate leakage current. Although the device is still being developed and improved, it still shows the potential of combining the new PNP-GaN gate HEMT and MIS gate. It makes the gate bias of GaN HEMT closer to the range and reliability of traditional Si-based MOSFETs. | en_US |