WO/2007/077666 is referenced by 58 patents.

(EN) This invention provides a group III nitride-type field effect transistor that can reduce a leak current component derived from the conduction of residual carriers in a buffer layer to improve proof voltage and, at the same time, can improve carrier confinement effect of channels to improve pinch-off characteristics (to suppress short channel effect). For example, when the present invention is applied to a GaN-type field effect transistor, a composition modulated (composition gradient) AlGaN layer, in which the aluminum composition ratio is lowered gradually or stepwise toward the surface, is used as a buffer layer separately from GaN in a channel layer (hetero buffer). The total layer thickness a of an electron donation layer and the channel layer is selected so as to satisfy Lg/a ≥ 5 wherein Lg represents the gate length of FET to be prepared. In this case, the thickness of the channel layer is selected so as not to exceed, at room temperature, a value which is five times (about 500 Å) the de Broglie wavelength of two-dimensional electron gas accumulated in the channel layer.(JA)  本発明は、III族窒化物系電界効果トランジスタにおいて、バッファ層中の残留キャリアの伝導によるリーク電流成分を低減して耐圧向上を図り、かつ、チャネルの電子閉じ込め効果(carrier confinement)を向上させてピンチオフ特性を向上させる(ショート・チャネル効果を抑制する)。例えば、本発明をGaN系電界効果トランジスタに適用する際には、バッファ層として、チャネル層のGaNとは別に(ヘテロバッファ)、徐々にあるいはステップ状にアルミニウム組成を表に向かって低くした組成変調(組成傾斜)AlGaN層を用いる。電子供給層とチャネル層の層厚の合計aは、作製されるFETのゲート長Lgに対して、Lg/a≧5を満たすように選択し、その際、チャネル層の層厚は、室温において、チャネル層に蓄積される二次元電子ガスが示すド・ブロイ波長の5倍(約500Å)を超えない範囲に選択する。

Title
(Ja) 電界効果トランジスタ、ならびに、該電界効果トランジスタの作製に供される多層エピタキシャル膜
(En) Field effect transistor, and multilayered epitaxial film for use in preparation of field effect transistor
Application Number
PCT/JP2006/321275
Publication Number
2007/077666
Application Date
October 25, 2006
Publication Date
July 12, 2007
Inventor
Okamoto Yasuhiro
Wakejima Akio
Kuroda Naotaka
Yamanoguchi Katsumi
Miyamoto Hironobu
Ota Kazuki
Murase Yasuhiro
Ando Yuji
Nakayama Tatsuo
Inoue Takashi
Agent
MIYAZAKI Teruo
Assignee
Okamoto Yasuhiro
Wakejima Akio
Kuroda Naotaka
Yamanoguchi Katsumi
Miyamoto Hironobu
Ota Kazuki
Murase Yasuhiro
Ando Yuji
Nakayama Tatsuo
Inoue Takashi
Nec Corporation
IPC
H01L 29/812
H01L 29/778
H01L 21/338
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