於藍寶石基板之高功率氮化鎵 p-i-n二極體之研製

Study and Fabrication of High Power GaN p-i-n Diodes Grown on Sapphire

張永富(Chang, Yung Fu)

指導教授 ： 吳孟奇 ； 何充隆

國立清華大學/電機資訊學院/電子工程研究所/博士(2015年)

摘要

於本論文中，將於圖形化藍寶石基板(PSS)上利用有機金屬化學沉積法(MOCVD)所成長的p-i-n二極體晶圓，利用嚴謹的製程技術製作並研究高功率氮化鎵(Gallium Nitride ; GaN) p-i-n二極體的元件電特性。當操作於逆向偏壓下，由於高功率氮化鎵p-i-n二極體元件須具有高崩潰電壓的能力，因此必須仰賴良好的缺陷抑制能力；同時，於順向偏壓操作下，此元件追求更低的功率消耗，故須具備相當低的串聯電阻。
於本論文中，高功率氮化鎵p-i-n二極體的元件利用二階段的平台結構的設計抑制元件邊緣效應，包含製程所造成的缺陷影響及逆向電場於元件平台的影響等，進而獲得良好的逆向崩潰特性。在發現適當的元件結構後，以此結構製作並研究在i層具有極低載子濃度的氮化鎵p-i-n二極體元件。最後，利用二階段的平台結構的設計結合適當的平台邊緣處理技術，在具有極低i層載子濃度的磊晶結構下，得到接近800 V的逆向崩潰電壓以及其巴利加優值（Baliga’s Figure of Merit, BFOM）接近碳化矽(SiC)極限效能的優良結果。

關鍵字

氮化鎵 ； 高功率 ； p-i-n二極體 ； 整流器

並列摘要

In this study, the Gallium Nitride (GaN) p-i-n diodes grown on pattern sapphire substrates by MOCVD have been fabricated to study the electrical characteristics of the GaN p-i-n diodes. To be a great high power device, the reverse breakdown characteristics of GaN p-i-n diodes are dominated by the capabilities of defect suppression at reverse bias; at the same time, the forward series resistances of GaN p-i-n diodes must be reduced for low power dissipation at forward bias.
In this study, firstly, the edge termination effects of the GaN p-i-n diodes including the damages resulted from ICP etching and electric field distribution were inhibited by using two-step mesa structure and suitable process parameters, and these fabricated devices exhibited great performances. After the suitable process flow has been confirmed, the GaN p-i-n diodes with ultra-low i- layer concentration have been fabricated.
Finally, the results of the devices with ultra-low i- layer concentration and two-step mesa structures show the high BFOM values and the high breakdown voltage values, respectively. The device with the highest BFOM is very close to the dash line for SiC-limit. The fabricated devices with suitable process parameters and low i- layer concentrations are greater than the previous reports of the GaN p-i-n diodes grown on sapphire substrates.

並列關鍵字

GaN ； high power ； p-i-n diode ； rectifier

參考文獻

[1] K. Y. Yen, C. H. Chiu, C. W. Li, C. H. Chou, P. S. Lin, T. P. Chen, T. Y. Lin, and J. R. Gong, "Performance of InGaN/GaN MQW LEDs Using Ga-Doped ZnO TCLs Prepared by ALD," IEEE Photon. Technol. Lett., vol. 24, no. 23, pp. 2105-2108, Dec 2012.

[2] C. L. Liao, Y. F. Chang, C. L. Ho, and M. C. Wu, "High-Speed GaN-Based Blue Light-Emitting Diodes With Gallium-Doped ZnO Current Spreading Layer," IEEE Electron Device Lett., vol. 34, no. 5, pp. 611-613, May 2013.

[3] C. Y. Lee, C. C. Huang, C. L. Liao, Y. F. Chang, S. F. Chen, C. L. Ho, J. Z. Liu, and M. C. Wu, "Enhanced Light Extraction for InGaN/GaN LEDs Using Zn and Mg Driven-In ALD-GZO as Transparent Conducting Layer," IEEE Electron Device Lett., vol. 34, no. 10, pp. 1283-1285, Oct 2013.

[4] C. M. Yang, D. S. Kim, S. G. Lee, J. H. Lee, and Y. S. Lee, "Improvement in Electrical and Optical Performances of GaN-Based LED With SiO2/Al2O3 Double Dielectric Stack Layer," IEEE Electron Device Lett., vol. 33, no. 4, pp. 564-566, Apr 2012.

[6] B. Cougo, H. Schneider, and T. Meynard, "High Current Ripple for Power Density and Efficiency Improvement in Wide Bandgap Transistor-Based Buck Converters," IEEE Trans. Power Electron., vol. 30, no. 8, pp. 4489-4504, Aug 2015.