SpinFET Raja Shekar Baddula – 134366001
Sreejith K P – 133076005
Titto Thomas – 133079015
Nandakumar S R - 133070053
Need of Nanostructure device
Spin of a electron S = ħσ/2
Magnetic moment of a electron µspin = -gµBS/ ħ
σ = Pauli spin operator
µB = Bohr magnetron (eħ/2m)
Miniaturization Problems
Power dissipation
Short channel effects
Quantum mechanical
effects
ballistic
tunneling
http://www.nims.go.jp/apfim/SpinFET.html
Spin FET
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Atomic case
In Electron rest frame
Amperes' law
Heterojunction:
In analogy with the atomic
case Rashba S-O term
0 0( )eff nucleusB v E
2( )B
S O spin eff
g SE B v E
hc
2( )
2
BS O
gH p V
mc
ˆdV
V zdz
2[ ( )]
2
BS O
g dVH p z
mc dz
2[ ( )]
2
BS O
g dVH z p
mc dz
[ ( )]S OH z ph
2 21( ) ( )
2x y x y y xH p p p p
m h
, ,
y
k x k
k
k
, ,
xk y k
k
k
, , 0k z k
Spin-Orbit interaction
0
24
j rB
r
j Zev
2
0
ˆ
4nucleus
Ze rE
r
AlGaAs
InGaAs
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RA: Resistance in the antiparallel configuration
RP: Resistance in the parallel configuration
Giant magnetoresistance (GMR)
http://www.aist.go.jp/aist_e/latest_research/2004/20041124/20041124.html
http://www.nims.go.jp/apfim/halfmetal.html
http://www.directvacuum.com/spin.asp
Origin of GMR
Parallel Antiparallel
Mott Model
Different resistivities
Scattering is :
Strong for electrons with spin antiparallel to the magnetization direction
Weak for electrons with spin parallel to the magnetization direction
EE733 : SpinFET 5
H. Ehrenreich and F. Spaepen, Academic Press, 2001, Vol. 56 pp.113-237
http://physics.unl.edu/tsymbal/reference/giant_magnetoresistance/origin_of_gmr.shtml
SpinFET : Structure & Working
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Electron spin photon polarization
Supriyo Datta & Biswajit Das, Electronic analog of the eiectro-optic modulator, APL ,1989
http://nanohub.org/resources/11128
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Structure & Working of spinFET
Supriyo Datta & Biswajit Das, Electronic analog of the eiectro-optic modulator, APL ,1989
Satoshi Sugahara and Junsaku Nitta, Spin-Transistor Electronics: An Overview and Outlook, 2010
http://nanohub.org/resources/11128
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=
Spin Injection Source(polarizer) and drain(analyzer) made of
ferromagnetic material(Fe).
Conditions with the polarizer (source) and analyzer
(drain) magnetizations parallel or antiparallel, resulting
in relatively high or low spin-dependent voltages at the
detector.
Conductance(G) = 𝑞2𝐷/𝑡.
Supriyo Datta & Biswajit Das, Electronic analog of the eiectro-optic modulator, APL ,1989
Satoshi Sugahara and Junsaku Nitta, Spin-Transistor Electronics: An Overview and Outlook, 2010
http://nanohub.org/resources/11128
EE733 : SpinFET 9
2DEGs in narrow band gap semiconductor
Ballistic tranport
Avoid spin relaxation[1]
Elliot Yafet
D'yakonov-Perl
Bir-Aronov-Pikus
[1] J. Fabian and S. Das Sarma, Spin relaxation of conduction electrons, 1993
[2] Satoshi Sugahara and Junsaku Nitta, Spin-Transistor Electronics: An Overview and Outlook, 2010
[2]
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Channel Requirements
[1] J. Nitta, F. E. Meijer, and H. Takayanagi, Spin-interference device, 1999
[2] Satoshi Sugahara and Junsaku Nitta, Spin-Transistor Electronics: An Overview and Outlook, 2010
[2]
Applied potential controls
the polarization of the
electron
Aharonov – Bohm
Experiment
Conductance
variation
Phase difference in the
wave vector
[1]
∆𝜽 = 𝟐 𝒎∗𝜼𝒍
ћ𝟐
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Electrostatic control of spin
Satoshi Sugahara and Junsaku Nitta, Spin-Transistor Electronics: An Overview and Outlook, 2010
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Gate control of the channel
J. Schliemann, J. C. Egues, and D. Loss, Nonballistic spin-field-effect transistor, 2003
[1] Satoshi Sugahara and Junsaku Nitta, Spin-Transistor Electronics: An Overview and Outlook, 2010
[1]
Scattering tolerent
Dresselhaus spin-orbit
coupling
Making both the
coefficients equal
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Non-ballistic SpinFET
[1] D. M. Gvozdie, U. Ekenberg, and I. Thylen, Comparison of performance of spin transistors with conventional transistors, 2005
[2] J. Wan, M. Cahay, and S. Bandyopadhyay, Proposal for a dual-gate spin field effect transistor: A device with very small
switching voltage and a large ON to OFF conductance ratio, 2008
Improvements
Holes as carriers
Strain engineering to shift the hole subbands
Modified device structure
Gate control hinderance
Fano resonance
Ramsauer resonance
Dual gate as an option
[1]
[2]
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SpinFET improvemts
Spintronics so far..
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Discovered by Albert Fert
and Peter Gruenberg
independently in 1988.
IBM researcher Stuart Parkin
created hard disk read
heads, which tremendously
improved data storage and
speed.
Nobel prize for GMR in
2007.
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Giant Magneto-Resistance (GMR)
MRAM
Non-volatile
Lower power consumption
than a DRAM
Write power only slightly
greater than read.
Slightly lower performance
than SRAM
Viewed as a universal
memory element.
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Memory Applications
Depending on the relative direction of magnetization of
Free electrode relative to the Fixed magnetization
electrode the channel will provide a low/high resistance .
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SpinFET based Memory
AND Logic NAND Logic
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Magnetoelectric Spin-FET for Memory, Logic,and Amplifier Applications, S. G. Tan et al., 2005
Logic Applications
A family of silicon-based semiconductors that exhibit
magnetic properties has been discovered in 2004.
A team of Princeton scientists has turned semiconductors into
magnets by the precise placement of metal atoms within a
material from which chips are made in 2006.
Scientists prove the existence of a spin battery.
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Things that gives hope..
Thank You
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