依據電氣參數特性以均勻篩選串疊型氮化鎵 場效電晶體之方法研究

Abstract

本研究檢測氮化鎵場效電晶體之輸出電性特性。電性特性量測包含輸出特性曲線(IDS-VDS)、臨限電壓(IDS-VGS)及功率寄生電容(C-VDS)的量測。透過輸出特性曲線量測可以檢知功率電晶體最大飽和電流、轉角電壓及導通電阻等特性；臨限電壓量測可以檢知多少閘極偏壓下能使功率電晶體導通；寄生電容量測則可以得知功率電晶體寄生電容影響功率電晶體的開關切換速度。量測的電性特性規格建立在參考市售加強型、空乏型的金屬氧化物半導體場效電晶體及加強型氮化鎵場效電晶體。比較目前加強型氮化鎵場效電晶體及交大實驗室所研發空乏型氮化鎵場效電晶體之輸出電性特性。透過建立一套標準規格的電性量測可以提供設計上所需的必要資訊，並可將量測的電性參數建立至元件等效電路模型以模擬實際電路。高功率的輸出應用勢必需並聯多個功率晶體，因此晶體的電性萃取、參數的差異篩選及電性特性模型建立對於晶體的並聯均流在功率系統中是一門相當重要的議題。透過提出了一種隔離閘極驅動器檢測方法，從電晶體關斷的阻抗能力得以篩選元件的均勻性。此外，基於測量的電氣特性建立了氮化鎵場效電晶體的等效電路模型，並通過實驗驗證，提出了一種使用實驗參數萃取所建立的串疊型封裝之氮化鎵場效應晶體的簡單行為模型，採用LTspice模擬軟體比較實驗切換結果，模擬結果與實驗結果吻合。

This study examined the output electrical characteristics—output characteristics (IDS–VDS), transfer characteristics (IDS–VGS), and parasitic capacitance (C–VDS)—of novel gallium nitride (GaN) power transistors. Experimental measurements revealed that both enhancement- and depletion-mode GaN field-effect transistors (FETs) containing different components of identical specifications yielded varied turn-off impedance. Establishing standardized electrical measurements can provide necessary information for designers, and measuring transistor electrical characteristics establishes its equivalent-circuit model for circuit simulations. Moreover, high power output requires multiple parallel power transistors, and sorting the difference between similar electrical characteristics is critical in a power system. An isolated gate driver detection method is proposed for sorting the uniformity from the option of the turn-off characteristic. In addition, an equivalent-circuit model for GaN FETs is established on the basis of the measured electrical characteristics and verified experimentally. LTspice simulation software was adopted to compare the experimental switching results. Overall, the simulation results were strongly in agreement with the experimental results.