2 2 2 2 2 2

qN a

Si
E x ,y E x ,y E x ,y C X Y Z
2
si toxtsi 2 ox
3
si toxtsi 3 ox
4
si toxtsi 4 ox
Isabelle Ferain, Cynthia A. Colinge ,et al. nature(2011)
Current ON/OFF > 10^6 SS =64mv/decade close to the theoretical limit
Strikingly similar to regular MOSFETS
3
Applications
1D2D Field-Effect Transistor
Sujay B. Desai, Surabhi R. Madhvapathy, et al. Science(2016)
Structure : n channel MOSFET
Isabelle Ferain, Cynthia A. Colinge ,et al. nature(2011)
2
The principle of field - effect transistors
2
The principle of field - effect transistors
3. A new type of transistor
Nanowire Transistors Without Junctions 1D2D Field-Effect Transistor(1-nanometer gate lengths) Field-Effect Tunneling Transistor Based on Vertical Graphene Heterostructures
4
Summary
1. Fundamental characteristics
I-V characteristics Transfer characteristics Subthreshold characteristics
2. Characteristics with scaling down
Velocity saturation Ballistic transport Drain-induced barrier lowering(DIBL) effect
I-V characteristic
2
The principle of field - effect transistors
Subthreshold VG <VT
当栅电压低于阈值电压时，半导体表面呈弱反型或 耗尽，相应的漏电流称为亚阈值电流，尽管亚阈值 电流较小，但亚阈值电流随栅压急剧地变化，因而 对低电压、底功耗应用特别的重要。
Thanasis Georgious, Rashid Jail, et al. nature nanotechnology(2013)
3
Applications
Field-Effect Tunneling Transistor Based on Vertical Graphene Heterostructures
si toxtsi ox
x (x ) 0 exp( ) 1
1
2
The principle of field - effect transistors
Multigate field effect transistor
x ,y x ,y x ,y x y z
Thank you!
28
3
Applications
1Байду номын сангаас2D Field-Effect Transistor
3
Applications
Field-Effect Tunneling Transistor Based on Vertical Graphene Heterostructures
L. Britnell , R.V. Gorbachev , et al. Science(2012)
2
The principle of field - effect transistors
Ballistic transport
由于载流子（在运动过程）要经历大量的散射事件，速度饱和是一个稳态 平衡现象。然而，当沟道长度与平均自由程同等量级或者小于平均自由程 时，沟道载流子不会遭受散射而失去从电场获得的能量，因而其速度可以 比饱和速度高得多。 器件的电流和跨导都比速度饱和时高，这也是不断缩小器件尺寸的动力。
3
Applications
Nanowire transistors without junctions
Jean-Pierre Colinge, Chi-Woo Lee et al, nature nanotechnology(2010)
3
Applications
Nanowire transistors without junctions
2
The principle of field - effect transistors
Poisson’s equation:
Avoid short-channel effect
x ,yx ,yqN a qN a x ,yx ,y x ,y x x y y z Si Si
d x ,y dy
y 0

ox f x gs C 1 x si tox
x s x gs
qN a 2 1 si
d(x ,y ) 3. dy
y tsi
C 1 x 2tsiC 2 x 0
d 2(x ) (x ) 2 0 令y=0 ， dx 2 1
3
Applications
Field-Effect Tunneling Transistor Based on Vertical Graphene Heterostructures
3
Applications
Field-Effect Tunneling Transistor Based on Vertical Graphene Heterostructures
2 2 2 2 2 2 2 2 2 2
x ,y C 0 x C 1 x y C 2 x y 2
In case of a single-gate SOI device the boundary conditions to equation are:
1. x , 0 s x C 0 x 2.
Institute of Physics, CAS
Field Effect Transistors
Liang Zhu SF01 Supervisor: Xuedong Bai Oct. 28,2016
CONTENTS
1
Backgrounds
2 The principle of field effect transistors
Current ON/OFF > 10^6 SS < 60mv/decade (the theoretical limit , Si )
3
Applications
Field-Effect Tunneling Transistor Based on Vertical Graphene Heterostructures
典型值：
70mv — 100mv/decade VG – VT < -0.5V
1
亚阈值电流可以忽略
2
The principle of field - effect transistors
Velocity saturation
在高场下，迁移率不再是常数，随着VD的增加，载流子速 度趋于饱和。表现也是电流开始时增加，然后达到饱和。但 此时的饱和机理与恒定迁移率不同，在夹断之前发生。
3
Applications
1D2D Field-Effect Transistor
larger electron effective mass along the transport direction (mn* ∼ 0.55m0 for MoS2 versus mn* ∼ 0.19m0 for Si [100])
2
The principle of field - effect transistors
Subthreshold Swing
量化MOS管如何随栅压快速关断 的参数称为亚阈值摆幅S（亚阈值 斜率的倒数），定义为漏电流减 小一个数量级所需的栅电压的变 化量。
S lg I D / VG
JACQUES G.RUCH ,IEEE TRANSACTIONS ON ELECTRON DEVICES,1972
2
The principle of field - effect transistors
Drain-induced barrier lowering(DIBL) effect
短沟道时，源和漏的耗尽层宽度之和约等于沟道长度，出现穿通，结果是在源 和漏之间产生很大的漏电流（leakage current）。 其原因是DIBL效应，即源漏之间势垒下降，短沟道时更明显。
3
4
Applications Summary
1
Backgrounds
The key words are here!
W.Shockley W.Brattain J.Bardeen
Noble prize:1956
1
Backgrounds