龐磁電容及負電容效應之鍺場效電晶體驗證

The Demonstration of Colossal Magnetocapacitance and ＂Negative＂ Capacitance Effect with the Promising Characteristics of Jg-EOT and Transistor's Performance on Ge (100) n-FETs by the Novel Magnetic Gate Stack Scheme Design

陳品光 ； 連慶 ； 葉佳翰 ； 廖洺漢

《國家奈米元件實驗室奈米通訊》 22卷1期 (2015/03) Pp. 2-7

摘要

提升場效電晶體的元件性能，除了可以利用元件通道尺寸的微縮之外，鍺材料是近年被關注的材料之一，它擁有比傳統矽材料更高的電子與電洞遷移率。然而在鍺場效電晶體中，如何有效改善EOT（Equivalent Oxide Thickness）與抑制閘極的漏電變得相當重要。此篇論文，利用BaTiO_3作為鍺場效電晶體的閘極絕緣層，同時搭配FePt磁性金屬為閘極，我們發現FePt磁性金屬作為閘極，可以誘發大量的極化電荷於BaTiO_3絕緣層中，產生超高介電常數（κ value），我們稱之為龐磁電容效應。除此之外，在元件上我們亦可觀察到負電容效應，最終，此新穎閘極結構提升～75%之介電常數（κ value）及提升～50%導通電流（I_(on)），並降低漏電（J_g）～100倍。

關鍵字

龐磁電容 ； 負電容 ； 鍺電晶體

並列摘要

TSuper Jg-EOT gate stack characteristics, ultra-high κ value, and the promising transistor's performance are achieved on the Ge n-FET by the application of the BaTiO_3 as the gate dielectric and the magnetic FePt film as the metal gate. The super Cgate/κ-value is generated by more dipoles in the HK dielectric layer with the coupling of the build-in magnetic field from MG (HK: BaTiO_3; MG: magnetic FePt). With the demonstration of this classical＂ colossal magneto-capacitance＂ effect in this work, the κ value can be improved ~75% successfully together with the reduction of Jg ~100X and the Ion is improved ~50% accordingly. On the other hand, the ＂negative＂ capacitance effect, which is important for the future steeper sub-threshold swing (S.S) device design, is also observed. The novel gate stack scheme (BaTiO_3 HK+ FePt MG), proposed in this work, with the super Jg-EOT characteristics,＂ negative＂ capacitance phenomenon, and the promising transistor's performance on the high mobility (Ge) material provides the useful solution for the future low power mobile device design.

並列關鍵字

Colossal Magneto-capacitance ； Negative Capacitance ； Ge FET