Effects of Remote Screening on Carrier Transport in Buried Two-Dimensional Electron and Hole Gases by Surface Tunneling
Yi-Hsin Su1*, Kuan-Yu Chou1, Yen Chuang1, Po-Yuan Chiu2, Nai-Wen Hsu2, Tzu-Ming Lu3, Jiun-Yun Li1,2,4
1Graduate Institute of Electronic Engineering, National Taiwan University, Taipei, Taiwan
2Department of Electrical Engineering, National Taiwan University, Taipei, Taiwan
3Sandia National Laboratories, Albuquerque, NM, USA
4National Nano Device Laboratories, Hsinchu, Taiwan
* presenting author:Yi Hsin Su, email:r04943070@ntu.edu.tw
利用半導體異質結構(semiconductor heterostructure)形成埋入二維電子或電洞氣(buried two dimensional electron/hole gas),已被用於量子點量子計算元件製作或研究自旋電子學的固態物理系統1,2,為有效地利用表面閘極控制其下的二維系統,本研究將深入探討表面特性及其對埋入二維載子的影響。我們發現表面的遠端載子屏蔽效應(remote carrier screening),對於矽二維電子(Si 2DEG)與鍺二維電洞(Ge 2DHG)皆大幅增強其載子遷移率(分別為4倍與2倍),表面屏蔽發生的原因主要是在高閘極電壓下,位於埋入層的二維電子或電洞穿隧到表面並形成一屏蔽層,進而減弱表面與氧化層間之雜質對二維電子/電洞的遠端散射作用,故使其遷移率增加。此外,我們也首次觀察到持續增加閘極電壓,二維電子/電洞系統將經由表面穿隧效應(surface tunneling)3從非平衡態回復至平衡態。


參考文獻-
[1] K. Wang et al., Phys. Rev. Lett. 111, 046801 (2013)
[2] R. Winkler, Spin-Orbit Coupling Effects in Two-Dimensional Electron and Hole Systems (Springer Berlin Heidelberg, 2003)
[3] T.M. Lu et al., Appl. Phys. Lett. 99, 153510 (2011)


Keywords: 二維電子, 二維電洞, 屏蔽效應, 穿隧效應, 遷移率