様々なバンド不連続を有するAl_xGa_<1-x>N/SiCヘテロ接合バイポーラトランジスタの電流輸送機構

Abstract

様々なバンド不連続を有するAl_xGa_<1-x>N/SiCヘテロ接合バイポーラトランジスタ(HBT)について, ガンメルプロットを用いて電流輸送機構を調べた.低コレクタ電流域において, ベース電流は再結合電流が支配的であり, その大きさはAl組成ごとに異なるものの, 系統的な違いはなかった.また, バンド不連続が異なるにもかかわらず, すべてのAl組成においてコレクタ電流の電流-電圧特性が一致し, そのn値は1.0であった.このことから, コレクタ電流はベース層での拡散が支配的であり, AlGaNエミッタからの電子注入は余分な電圧降下なしに行われている.

The current transport characteristics of the quasi-Al_xGa_<1-x>N/SiC Heterojunction Bipolar Transistors (HBTs) with various band discontinuities were investigated in the low current range by means of Gummel plot. In the low current range, the base currents of the HBTs were dominated by recombination currents and the amount of recombination among the HBTs were different. The collector current characteristics of the HBTs were almost the same in spite of the various band discontinuities and the ideality factors n were 1.0. The collector currents were dominated by the diffusion process in the base region and electrons were injected from the AlGaN emitter without any additional voltage drops in the low current range.