氮化鎵高電壓蕭特基二極體之製作

Fabrication of GaN High Voltage Schottky Diodes

黃文賓(Wen-Pin Huang)

指導教授 ： 綦振瀛

國立中央大學/資訊電機學院/電機工程學系/碩士(2006年)

摘要

追求高品質的電力供需，一直是全球各國想要達到的目標，大量的興建電廠並非解決問題的途徑，而是要提高電器產品的效率，才能有效解決問題。本論文研究具有高崩潰電壓、大操作電流及短逆向回復時間之氮化鎵蕭特基二極體製作，元件結構分為n型氮化鎵與AlGaN/GaN元件結構。對於n型氮化鎵元件結構，我們利用2.8μm未摻雜n型氮化鎵製作平台式蕭特基二極體，可獲得190V的崩潰電壓，以及利用不同溫度下之電流-電壓特性曲線分析載子的傳輸行為。
平面式FP AlGaN/GaN異質接面元件結構，獨特的極化效應在界面附近自動感應形成高電子濃度與高遷移率的通道，能夠減少RON電阻值。在元件結構中，利用Field Plate技術分散蕭特基電極邊緣的電場並藉由DESSIS軟體模擬元件的內部電場分佈，獲得最佳化FP氮化矽厚度並製作蕭特基二極體元件。在800nm厚度下，可達到475V的崩潰電壓，此元件在室溫下的VF與RON，分別為2.4V與13mΩ-cm2，評量因子（F.O.M）為17.1MW/cm2。40 finger指叉型AlGaN/GaN蕭特基二極體，在外加3.5V時，可以得到2.5A的順向電流輸出，元件崩潰電壓可達436V。當元件輸入4A順向電流時，蕭特基二極體逆向回復時間（trr）約15ns比Si元件的30ns降低一半。

關鍵字

高崩潰電壓 ； 蕭特基二極體 ； 氮化鎵

並列摘要

It is the goal that the global various countries have wanted to reach all the time to pursue the electric supply and demand of high quality, a large number of construction power plants do not solve the way of the problem, but should improve the efficiency of the electric equipment products. In this thesis, we studied on GaN Schottky diodes with mesa-type n-GaN and planar-type AlGaN/GaN, operating at high forward current and high breakdown voltage. In Mesa-type n-GaN Schottky diodes, having a drift region of 2.8?m thickness and doping concentration of 5×1016/cm3, show a breakdown voltage of about 190V. We report I-V characteristics, both at room temperature and in the temperature range 300 to 423K, of Mesa type GaN Schottky diodes fabricated on expitaxial layers incorporating double GaN/SiN nucleation layers.
For a more significant reduction of the on-state resistance, AlGaN/GaN heterostrure devices are attractive due to their high mobility and high carrier density of two-dimensional electron gas at the AlGaN/GaN interface. In planar-type AlGaN/GaN Schottky diodes, we studied simulation and fabrication of AlGaN/GaN rectifiers with field plate termination. The extent of metal electrode overlap and dielectric thickness were varied to ascertain their effects on the BV. The circular devices show on-resistance (Ron) of about 13m?-cm2. The experimental breakdown data shows that there is an optimum Si3N4 thickness for which the breakdown voltage (BV) is highest and on either side of this optimum Si3N4 thickness, the BV voltage decreases. In the present case, the highest BV of about 475V is obtained when silicon nitride thickness is around 800nm and the Schottky diodes exhibit a figure of merit (VB2/Ron) of about 17MW/cm2. The 40 finger-type AlGaN/GaN Schottky diodes with wire bonding obtained a forward current 2.5A at an applied forward voltage of 3.5V, and BV of about 436V. In reverse recovery characteristics of the finger-type AlGaN/GaN Schottky rectifiers, when the diode was switched from forward to reverse bias, the device exhibited an ultrafast switching time (trr) 15ns less than 30ns of Si-based device.

並列關鍵字

High breakdown voltage ； Schottky diodes ； GaN

參考文獻

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