Investigation of Performance Limits of Germanium Double-Gated MOSFETs

摘要：

The performance limits and engineering issues of ultra-thin body (UTB) double gated (DG) Ge channel n- MOSFETs are examined in this paper. The non- equilibrium Greens Function (NEGF) approach, including both L and △ conduction valleys, is employed for source to drain current, while the improved WKB tunneling is employed for substrate to drain (band-to-band BTB) and gate to channel current. All possible Ge surfaces and channel orientations are explored. In terms of drive current I<,ON>, highly anisotropic Ge<110> channel exhibits highest I<,ON> which increases with body thickness scaling; Ge<100> exhibits similar ballistic limit as Si<100> due to increasing △ valley carrier dominance at UTB regime; Ge<111> exhibits higher ballistic limit but decrease at UTB regime due to the small density-of-states mass of L valley. Sub-threshold slope is worse for Ge<110> and Ge<111> as channel length is scaled down. In terms of standby current I<,OFF> and gate leakage I <,G> for low standby power (LSTP) devices, BTB tunneling is large due to the small energy gap of Ge. This imposes a limit on maximum tolerable supply voltage (of which Ge<111> is worst and Ge<100> is best) thus requiring low voltage operation. Body scaling is effective in suppressing BTB tunneling, since carrier quantization causes effective energy gap widening. The low voltage requirement demands small EOT for minimal oxide voltage drop. However, gate leakage will impose a limit for further EOT scaling, of which Ge <110> is worst and Ge <111> is best. Our results conclude that in addition to lower power supply voltage advantage, the engineered Ge <110> devices with suppressed BTB and gate leakages can achieve better intrinsic delay to OFF power ratio than Si<100> devices.

作者: Tony Low Y. T. Hou M. F. Li Chunxiang Zhu Albert Chin G. Samudra L. Chan D. -L. Kwong

作者单位: Silicon Nano Device Lab (SNDL), ECE Department, National University of Singapore, Singapore 119260 Silicon Nano Device Lab (SNDL), ECE Department, National University of Singapore, Singapore 119260 I Dept. of Electronics Eng., National Chiao Tung Univ., Hsinchu, Taiwan Technology Development, Chartered Semiconductor Manufacturing, S738406, Singapore Dept. of Electrical and Computer Engineering, University of Texas, Austin, TX 78712, USA

会议类型: 国际会议

会议名称: 2007年纳米电子器件研讨会(Nano-Electron Device Workshop)

会议地点: 北京

会议语种:英文

页码: 46-49

在线出版日期: 2007-07-23（万方平台首次上网日期，不代表论文的发表时间）