本論文針對新型的 PNP閘極 (PNP-GaN gate)結構之氮化鎵高電子遷移率電晶體(HEMT)進行探討，該結構乃在傳統的p型氮化鎵閘極(p-GaN gate)結構中額外加入了一個PN-GaN二極體。研究包含新型元件的設計、 Silvaco TCAD元件特性模擬、元件製作以及電性測量分析，並比較新型的閘極結構與傳統p型氮化鎵閘極結構之元件特性差異。 相較於p-GaN gate HEMT，新型 PNP-GaN gate HEMT擁有較低的閘極漏電流，在 VGS = 10 V、 VDS = 10 V時低了147倍，此時新型 PNP-GaN gate HEMT 的導通電流/漏電流比(ID/IG)仍大於105。在閘極崩潰特性方面，新型 PNP-GaN gate HEMT達到了19.8 V，相比傳統 p-GaN gate HEMT，新閘極結構能有更大的電壓輸入範圍，閘極的十年壽命預估 也可以到達10.5 V。額外的PN氮化鎵二極體使閘極施加正偏壓時產生壓降，元件臨界電壓因此得到提升，新型 PNP-GaN gate HEMT臨界電壓為 2.96 V，額外的壓降也使蕭特基二極體有更低的電場強度增加了閘極可靠度與操作範圍。輸入電容由於PN-GaN的加入，相比一般 p-GaN gate HEMT有更小的閘極電容 。 此外，利用閘極絕緣層(isulator)進一步提升元件VTH以及降低閘極漏電流，提出的新型 MIS PNP-GaN gate HEMT也被製作，元件初步展示了具體增加的VTH和低的閘極漏電流。雖然元件仍在研發改善中，但仍展現了結合新型 PNP-GaN gate HEMT和閘極 MIS的元件潛力，讓 GaN HEMT的閘極偏壓更趨近於類似傳統 Si-based MOSFET的範圍和可靠度 。;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.
