IEE5328 Nanodevice Transport Theory and Computational Tools

Prof. Ming-Jer ChenDept. Electronics EngineeringNational Chiao-Tung UniversityApril 10, 2013

Lecture #4:

Ballistic I-V in 2DEG and 2DHG

(Advanced Device Physics with emphasis onhands-on calculations)

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High-Performance FETs projected by ITRS 2011 (http://www.itrs.net)

(Multi-Gates and SOI)

IEE5328 Prof. MJ Chen NCTU

Idsat

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High-Performance FETs projected by ITRS 2011 (http://www.itrs.net)

(Multi-Gates and SOI)

IEE5328 Prof. MJ Chen NCTU

Idsat

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Low-Power NanoFETs projected by ITRS 2011 (http://www.itrs.net)

(Bulk, SOI, and Multi-Gates)

IEE5328 Prof. MJ Chen NCTU

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Low-Power NanoFETs projected by ITRS 2011 (http://www.itrs.net)

(Bulk, SOI, and Multi-Gates)

IEE5328 Prof. MJ Chen NCTU

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Iballistic is simply due to thermionic injection over the source-channel barrier

Key Words:

But, Iballistic is usually much higher than Idsat you can experimentally obtain

This difference is due to a handful of physical phenomena:1.Effective Mobility and its reduction with channel length shrinkage 2.Backscattering in channel, in drain, and even in source

(rc well known in the channel)

3.Rsd4.Injection Velocity5.Source starvation6.Off-equilibrium transport

Iballistic is Idsat you can theoretically obtain

How can we shorten this gap such as to make experimental Idsat close to theoretical Iballistic?

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Two Basic Ways to calculate Iballistic:

1.Band Structure

2. MOS Electrostatics

Here, we focus on 2D case or the inversion layers of MOSFETs

2DEG: two-dimensional electron gas2DHG: two-dimensional hole gas

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2DEG or 2DHG

Originally derived by Prof. Natori

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Further Reading:

F.Assad, et al., “On the performance limits for Si MOSFET’s: A theoretical study,” IEEE Trans. Electron Devices, vol. 47, pp. 232-240, Jan. 2000.

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