Terahertz Electronics
Michael S. Shur
Electrical, Computer, and Systems Engineering and
Center for Integrated Electronics
Rm 9015, CII, Rensselaer Polytechnic Institute
110 8-th Street, Troy, New York 12180-3590
http://www.ecse.rpi.edu/shur/
Presented at Nano and Giga Challenges in Electronics,
Photonics, and Renewable Energy Conference
McMaster University
August 14, 2009
Michael Shur (shurm@rpi.edu) http://nina.ecse.rpi.edu/shur
1
Outline
• THz applications and “THz gap”
• State
State-of-the-art
of the art of THz electronics and THz transistor
• Ballistic transport -> unavoidable in modern transistors
– Ballistic “mobility”
– Ballistic admittance
Id = 5mA, Vgs=-0.4 V
500
• Plasma wave THz electronics
– Instability and THz generation
– Resonant and non-resonant THz detection
– Subwavelength imaging
– Plasma wave THz arrays
• Conclusions and future work
Y (μm)
400
300
200
100
0
0
100
200
300
400
500
X (μm)
From Veksler, D.B. Muraviev, A.V. Elkhatib, T.A.
Salama, K.N. Shur, M.S. , Plasma wave FET for subwavelength THz imaging
imaging,
International Semiconductor Device Research
Symposium December 12-14, 2007 College Park,
Maryland, USA
Michael Shur (shurm@rpi.edu) http://nina.ecse.rpi.edu/shur
2
THz applications
THz detection of concealed
weapons. 1 IEEE©(2007)
©(200 )
Hidden art revealed by
2
Terahertz.
h
THz image of ozone hole.3
IEEE©(2007)
©(200 )
1
R. Appleby and H.B. Wallace, “Standoff detection of weapons and contraband in 100 GHz to 1 THz
Region”, IEEE Trans. Antennas Prop. Vol. 55, p. 2944 (2007).
2
ScienceDaily (Feb. 5, 2008), http://www.sciencedaily.com/releases/2008/02/080204111732.htm.
3
F. Pieternel, E. Levelt, G. W. Hilsenrath, C.H.J. Leppelmeier, P.K. van den Oord, J. Bhartia, J. F.
Tamminen, J.P. de Hann, and J.P. Veefkind, “Science objectives of the ozone monitoring instrument”,
IEEE Trans. On Geoscience And Remote Sensing, Vol. 44, No. 5, pp. 1199-1208 (2006).
Michael Shur (shurm@rpi.edu) http://nina.ecse.rpi.edu/shur
3
THz Applications
THz cancer detection.1
THz applications in
dentistry.2
Explosive detection using THz
radiation.3
1
PTBnews: http://www.ptb.de/en/publikationen/news/html/news021/artikel/02104.htm.
BBC News, Monday, June 14, 1999, news.bbc.co.uk/1/hi/sci/tech/368558.stm.
3
Y. Chen, H. Liu, M.J. Fitch, R. Osiander, J.B. Spicer, M.S. Shur, X.-C. Zhang, “THz diffuse reflectance
spectra of selected explosives and related compounds”
compounds , Passive Millimeter
Millimeter-Wave
Wave Imaging Technology
VIII. Edited by R.J. Hwa, D.L. Woolard, and M.J. Rosker, Proc. of SPIE, Vol. 5790, p. 19 (2005).
2
Michael Shur (shurm@rpi.edu) http://nina.ecse.rpi.edu/shur
4
THz gap
From W.J. Stillman and M.S. Shur, Closing the Gap: Plasma Wave Electronic
Terahertz Detectors, Journal of Nanoelectronics and Optoelectronics, Vol. 2,
Number 3, pp. 209-221, December 2007
Michael Shur (shurm@rpi.edu) http://nina.ecse.rpi.edu/shur
5
THz Schottky Diode
100 GHz – 2.5 THz
From http://www.acst.de/images/company_diode.jpg
http://www acst de/images/company diode jpg
Michael Shur (shurm@rpi.edu) http://nina.ecse.rpi.edu/shur
6
Mm wave Schottky diode in 0.13 micron process
O cell
One
ll layout
l
t
Diode cross section
From S. Sankaran, and K. K. O, “Schottky Barrier Diodes for mm-Wave and
D t ti iin a F
Detection
Foundry
d CMOS Process,”
P
” IEEE Elec.
El
Dev.
D
Letts.,
L tt vol.
l 26,
26 no. 7
7,
pp. 492-494, July 2005
Michael Shur (shurm@rpi.edu) http://nina.ecse.rpi.edu/shur
7
Resonant Tunneling Diodes
(Color online)
Fundamental structure
of the RTD oscillator
. (a) Slot resonator and
RTD, (b) potential
profile and current–
voltage characteristics
of RTD, and (c)
equivalent circuit of
(a).
(a)
Fundamental oscillation up to 0.65 THz and harmonic oscillation up to 1.02 THz
From Masahiro ASADA, Safumi SUZUKI, and Naomichi KISHIMOTO
“Resonant Tunneling Diodes for Sub-Terahertz and Terahertz Oscillators”
Japanese Journal of Applied Physics. Vol. 47, No. 6, 2008, pp. 4375–4384
Expected up to 60 microwatt at 2 THz
Michael Shur (shurm@rpi.edu) http://nina.ecse.rpi.edu/shur
8
0.41 THz Si 45 nm CMOS VCO
F
From
S.
S Lee,
L
B.
B Jagannathan,
J
th
S. Narasimha, Anthony Chou,
N. Zamdmer, J. Johnson, R.
Williams, L. Wagner, J. Kim, J.O. Plouchart, J. Pekarik, S.
Springer and G
G. Freeman,
Freeman
IEDM Technical Digest, p. 225
(2007)
After E. Y. Seok et al., “410-GHz CMOS
Push-push Oscillator with a Patch Antenna,”
2008 International Solid-State Circuits Conference,
pp 472-473,
pp.
472-473 Feb
Feb. 2008,
2008 San Francisco,
Francisco CA
Michael Shur (shurm@rpi.edu) http://nina.ecse.rpi.edu/shur
9
Northrop Grumman fmax is higher than 1 THz
From R. Lai, X. B. Mei, W.R. Deal, W. Yoshida, Y. M. Kim,
P.H. Liu, J. Lee, J. Uyeda, V. Radisic, M. Lange,
T. Gaier, L. Samoska, A. Fung, Sub 50 nm
InP HEMT Device with Fmax Greater than 1 THz,
IEDM Technical Digest, p. 609 (2007)
InGaAs/InP Based HEMT
35 nm g
gate device cross section
Michael Shur (shurm@rpi.edu) http://nina.ecse.rpi.edu/shur
10
Room Temperature Tunable Emission
300
2.5
2.0
200
1.5
1.0
100
1/f0 ((1/THz)
InSb Dete
ector Signal (mV
V)
3.0
0.5
0
0.0
0
0
02
0.2
04
0.4
06
0.6
08
0.8
0.0
Usd (V)
From D. B. Veksler, A. El Fatimy, N. Dyakonova, F.
Teppe, W. Knap, N. Pala, S. Rumyantsev, M. S.
Shur, D. Seliuta, G. Valusis, S. Bollaert, A.
Shchepetov, Y. Roelens, C. Gaquiere, D. Theron,
and A. Cappy,
ppy, in Proceedings
g of 14th Int. Symp.
y p
"Nanostructures: Physics and Technology" St
Petersburg, Russia, June 26-30, 2006, pp 331-333
From W. Knap, J. Lusakowski, T. Parenty, S. Bollaert,
A. Cappy, V. Popov, and M. S. Shur,
Appl. Phys. Lett. 84, No 13, 2331-2333,
2331 2333, March 29 (2004)
Michael Shur (shurm@rpi.edu) http://nina.ecse.rpi.edu/shur
11
THz transistors: issues
•Effective gate length is longer
•Parasitics are important
•Matching is difficult
•Device physics is different
–In THz transistors, electrons experience very few collisions
–Electron inertia is very important
–Electrons behave as a fluid
Michael Shur (shurm@rpi.edu) http://nina.ecse.rpi.edu/shur
12
Effective gate length
From V. O. Turin, M. S. Shur, and D. B. Veksler, IJHSES, vol. 17, No. 1 pp. 19-23 (2007)
Michael Shur (shurm@rpi.edu) http://nina.ecse.rpi.edu/shur
13
Effect of gate extension
From V. O. Turin, M. S. Shur, and D. B. Veksler, IJHSES, vol. 17, No. 1 pp. 19-23 (2007)
Michael Shur (shurm@rpi.edu) http://nina.ecse.rpi.edu/shur
14
Five-terminal HFET with additional biased
capacitively coupled contacts
Source C3
VS1
Dielectric
5
Gate
Drain C3
VD1
VS
VD
AlGaN
G
Source
2DEG
Drain
GaN
From G
G. Simin,
Simin M.
M Shur and R.
R Gaska,
Gaska IJHSES Vol
Vol. 19
19, No
No. 7
7–14,
14 1 (2009)
Michael Shur (shurm@rpi.edu) http://nina.ecse.rpi.edu/shur
15
Capacitively coupled contact with additional DC bias
V1
Capacitively-coupled
p
y
p
contact ((C3)
Dielectric
V0
S i
Semiconductor
d t
Ohmic or Schottky contact
After G. Simin, M. Shur, R. Gaska, Patent pending 2/12/2007
Michael Shur (shurm@rpi.edu) http://nina.ecse.rpi.edu/shur
16
Novel THz Device design:
5-terminal THz GaN HFET
35
35
HFET
5 term
5-term
MOSHFET
25
20
15
10
25
20
15
10
5
5
0
0
5
-5
5
-5
10
100
HFET
55-term
term
MOSHFET
30
H 221, dB
MSG
G/MUG, dB
30
1000
Frequency, GHz
10
100
1000
Frequency, GHz
Cut-off frequencies for regular (dash) and 5-terminal (solid) GaN
HFETs with 30-nm long gate (ADS simulations).
G. Simin, M. Shur and R. Gaska, ISDRS, accepted for publication (2009)
Michael Shur (shurm@rpi.edu) http://nina.ecse.rpi.edu/shur
17
Product Half Pitch, Gate length (nm)
Prod
duct half-p
pitch, gate length ((nm)
1000
100
Ballistic 10
silicon
1
FROM INTERNATIONAL TECHNOLOGY ROADMAP FOR SEMICONDUCTORS
2007 EDITION EXECUTIVE SUMMARY
Michael Shur (shurm@rpi.edu) http://nina.ecse.rpi.edu/shur
18
THz Performance Using Ballistic Transport
M. S. Shur and L. F. Eastman (1979)
From http://www.bell-labs.com/news/1999/december/6/1.html
Ballistic Transistor Has Virtually Unimpeded Current Flow (Dec. 6, 1999)
Intel Itanium 'leapfrog' to 32-nm
Colleen Taylor, Contributing Editor -- Electronic News, 6/14/2007
If the 25 nm node predicted by ITRS is reached in
2009 - 2010, all transistors will be ballistic
Michael Shur (shurm@rpi.edu) http://nina.ecse.rpi.edu/shur
19
Energy band, field, and concentration
profiles of n+-n-n+ sample in equilibrium
Fe rm i level
~L D
D i s ta
t nce
~LD
D i s ta n c e
D i s ta n c e
Michael Shur (shurm@rpi.edu) http://nina.ecse.rpi.edu/shur
20
Drude Equation and Equivalent Circuit
σ0
σ=
1 + iωτ
3D
o=
e
nS
L
Lm
L= 2
e nS
C
2D
o=e
ns W
m
L= 2
e ns W
Michael Shur (shurm@rpi.edu) http://nina.ecse.rpi.edu/shur
21
Energy band diagram for a ballistic sample
quasi-Fermi levels
Ec
Fermi level
in equilibrium
V/2
V
V/2
V/2
Distance
Conduction
C
d ti band
b d edge
d
in equilibrium
In the dashed energy region electron are moving only
from the left to the right
Michael Shur (shurm@rpi.edu) http://nina.ecse.rpi.edu/shur
22
DC Ballistic mobility
μbal
eL
=α
mv
Values of constant α and thermal and Fermi velocities for 2D and 3D geometries (see Eq.
(1)). kB is the Boltzmann constant, T is temperature (K).
Geometry
2D
3D
α=
2
π
α = 3/ 4
Degenerate
h
vF =
2πns [8]
m
(
h
vF = 3π 2ns
m
)
3/ 4
Non-degenerate
⎛ π kBT ⎞
1/ 2
1
α=
2
vth = ⎜
⎟ [4]
2 ⎠
⎝ 2m
2
⎛ 8k T ⎞
vth = ⎜ B ⎟ [3]
⎝ πm ⎠
α=
π
1/ 2
[3]A. van der Ziel, M. S. Shur, K. Lee, T. H. Chen and K. Amberiadis, IEEE Transactions on Electron Devices, Vol. ED-30,
No. 2, pp. 128-137, February (1983)
[4] M. Dyakonov and M. S. Shur, in, The Physics of Semiconductors ed. by M. Scheffler and R. Zimmermann (World Scientific,
1996), pp. 145-148, (1996)
[8] S
S. Rumyantsev
Rumyantsev, M
M. S
S. Shur
Shur, W
W. Knap
Knap, N
N. Dyakonova
Dyakonova, F
F. Pascal
Pascal, A
A. Hoffman
Hoffman, Y Ghuel
Ghuel, C
C. Gaquiere
Gaquiere, and D
D.
in Noise in Devices and Circuits II, Proceedings of SPIE Vol. 5470 , pp. 277-285 (2004)
Michael Shur (shurm@rpi.edu) http://nina.ecse.rpi.edu/shur
23
Mo
obility (cm2/V-s)
Experimental Evidence for Ballistic Mobility (after Shur (2002)
100000
50000
77 K
GaAs
300 K
10000
5000
0.1 0.2
0.5
1
2
5
Length (micron)
10
20
From M
M. S
S. Shur
Shur, IEEE EDL
EDL, Vol
Vol. 23
23, No 9
9, pp
pp. 511 -513,
513
September (2002)
Michael Shur (shurm@rpi.edu) http://nina.ecse.rpi.edu/shur
24
Ballistic Admittance in Quantum Wires
Re(Y)
1
However in 1D systems e-e
interaction might completely
destroy these oscillations
08
0.8
0.6
0.4
0.
2
0
5
10
Im(Y)
15
20
L/vF
After M.
Buttiker, J.
Phys Cond.
Phys.
Cond
Matter, vol. 5,
93-61 (1993)
L/vF
Michael Shur (shurm@rpi.edu) http://nina.ecse.rpi.edu/shur
25
Ballistic Admittance versus Frequency
Re(Y)
1
0.8
ω d Im Y
θ d Im y
Q=
=
Re Y dω
Re y dθ
0.6
0.4
0.
0
2
0
Im(Y)
5
10
15
20
L/vF
Q~7
L/vF
After A. P. Dmitriev and M. S. Shur, Appl. Phys. Lett., 89, 142102, (2006)
Michael Shur (shurm@rpi.edu) http://nina.ecse.rpi.edu/shur
26
Oscillation frequency
GaAs
GaN
Si
Device length ( m)
After A. P. Dmitriev and M. S. Shur, Appl. Phys. Lett., 89, 142102, (2006)
Michael Shur (shurm@rpi.edu) http://nina.ecse.rpi.edu/shur
27
Dispersion of Plasma Waves
3D
+
+
+
r
E
2D ungated
-
+
-r
2D gated
r
E
+
d
E
e2 N 3 D
ωp =
εε 0m
ωp =
ωp
ωp
k
e2 N 2D d
1
ωp =
k kd
kd<<1
εε 0 m
e2N2D
k
2 εε 0 m
ωp
k
Michael Shur (shurm@rpi.edu) http://nina.ecse.rpi.edu/shur
k
28
29
Plasma wave electronics
•Plasma wave instability
(D k
(Dyakonov‐Shur instability) Sh i
bili )
can be used for generation of THz radiation**)
THz
L
Gate
Source
ns
2D Channel:
δU~P
•Nonlinearity of plasma wave excitations can be used for THz
excitations can be used for THz detection*)
*)M. Dyakonov and M. S. Shur, IEEE Trans. Elec. Dev. 43, 380 (1996)
43
380 (1996)
**)M. Dyakonov and M. Shur, Phys. Rev. Lett. 71, 2465 (1993). Drain
Hokusai Print
Water wave analogy
Michael Shur (shurm@rpi.edu) http://nina.ecse.rpi.edu/shur
29
Plasma Wave THz Electronics
(Courtesy of W. Knap)
Michael Shur (shurm@rpi.edu) http://nina.ecse.rpi.edu/shur
30
2D Plasmonic Devices for THz Applications
THz Generators
THz Detectors
and Mixers
M. Dyakonov and M. Shur, IEEE
T-ED (1996)
K Guven
K.
G
et al.,
l PRB (1997)
(199 )
V. Ryzhii et al., JAP (2002)
W. Knap et al., APL, JAP
(2002)
X G Peralta
X.G.
P
l et al.,
l APL
PL (2002)
A. Satou et al., SST (2003)
V.V. Popov et al., JAP (2003)
V. Ryzhii et al., JAP (2003)
F Teppe
F.
T
et al.,
l APL (2005)
I.V. Kukushkin et al., APL
(2005)
D. Veksler et al., PRB (2006)
K
Knap
et all APL (2008)
Stillman et al (2008)
M. Dyakonov,
y
, M. Shur,, PRL (1993)
(
)
K. Hirakawa, APL (1995)
K. D. Maranowski, APL (1996)
V.V. Popov et al., Physica A (1997)
S.A. Mikhailov, PRB ((1998);
) APL ((1998))
P. Bakshi et al., APL (1999)
N. Sekine at al., APL (1999)
R. Bratshitsch et al., APL (2000)
Y. Deng
g at al., APL (2004)
(
)
W. Knap et al., APL (2004)
M. Dyakonov and M.S .Shur, APL (2005)
N. Dyakonova et al., APL (2006)
j APL (2006) DRC 2007
Otsuji
Otsuji LEC (2008)
Michael Shur (shurm@rpi.edu) http://nina.ecse.rpi.edu/shur
31
Plasma THz Electronics Advantages
•Small size (easy to fabricate matrixes/arrays)
•Compatible with VLSI technology
Id = 5mA, Vgs=-0.4 V
500
•For detectors:
Y (μm)
–High sensitivity
–Broad spectral range
–Band
Band selectivity and tunability
–Fast temporal response
400
300
200
100
0
0
100
200
300
400
500
X (μm)
Veksler, D.B. Muraviev, A.V. Elkhatib, T.A. Salama,
K.N. Shur, M.S. , Plasma wave FET for subwavelength THz imaging
imaging,
International Semiconductor Device Research
Symposium December 12-14, 2007 College Park,
Maryland, USA
Michael Shur (shurm@rpi.edu) http://nina.ecse.rpi.edu/shur
32
Plasma Waves in a Field Effect Transistor
•FET channel plays a role of a resonant cavity for plasma waves
50
Frequen
ncy (THz))
•Plasma frequency can be tuned by
can be tuned by gate‐to‐channel voltage
10
5
Plasma modes
Si
1
Transit mode
0.5
0.02
•Plasma waves can propagate much faster than electrons
faster than electrons
GaN
GaAs
0.5
0.05 0.1 0.2
Gate Length (micron)
1
From V. Ryzhii and M.S. Shur, Plasma Wave Electronics Devices,
ISDRS Digest, WP7-07-10, pp 200-201, Washington DC (2003)
Michael Shur (shurm@rpi.edu) http://nina.ecse.rpi.edu/shur
33
Radiation intensity from 1.5 micron
GaN HFET at 8 K
.
From Y. Deng, R. Kersting, J. Xu, R.
Ascazubi, X. C. Zhang, M. S. Shur, R.
Gaska,
G S.
G.
S Simin and M.
M A.
A Khan,
Khan and V.
V Ryzhii,
Ryzhii
Millimeter Wave Emission from GaN
HEMT,
Appl. Phys. Lett. Vol. 84, No 15, pp. 70-72,
January 2004
Inte
ensity (a.u.))
5.0
8 GHz cutoff
4.0
3.0
2.0
1.0
00
0.0
50
75
100
125
150
175
200
225
250
Frequency (GHz)
Michael Shur (shurm@rpi.edu) http://nina.ecse.rpi.edu/shur
34
Room Temperature Tunable Emission
300
2.5
2.0
200
1.5
1.0
100
1/f0 ((1/THz)
InSb Dete
ector Signal (mV
V)
3.0
0.5
0
0.0
0
0
02
0.2
04
0.4
06
0.6
08
0.8
0.0
Usd (V)
From D. B. Veksler, A. El Fatimy, N. Dyakonova, F.
Teppe, W. Knap, N. Pala, S. Rumyantsev, M. S.
Shur, D. Seliuta, G. Valusis, S. Bollaert, A.
Shchepetov, Y. Roelens, C. Gaquiere, D. Theron,
and A. Cappy,
ppy, in Proceedings
g of 14th Int. Symp.
y p
"Nanostructures: Physics and Technology" St
Petersburg, Russia, June 26-30, 2006, pp 331-333
From W. Knap, J. Lusakowski, T. Parenty, S. Bollaert,
A. Cappy, V. Popov, and M. S. Shur,
Appl. Phys. Lett. 84, No 13, 2331-2333,
2331 2333, March 29 (2004)
Michael Shur (shurm@rpi.edu) http://nina.ecse.rpi.edu/shur
35
THz response of CMOS (non-resonant)
NFETs
PFETs
First demonstration of terahertz and sub‐terahertz response in silicon CMOS
•
Extension earlier work on n‐channel Si FET response to p‐channel devices.
•
Compare and contrast n and p‐channel responsivity, detectivity and response speed in open drain and drain current enhanced response configurations.
From W. Stillman, F. Guarin, V. Yu. Kachorovskii, N. Pala, S. Rumyantsev, M.S. Shur, and D. Veksler,
Nanometer Scale Complementary Silicon MOSFETs as Detectors of Terahertz and Sub-terahertz Radiation,
in Abstracts of IEEE sensors Conference, Atlanta, GA, October 2007, pp. 479-480
Michael Shur (shurm@rpi.edu) http://nina.ecse.rpi.edu/shur
36
Non-resonant detection (ωτ<<1)
Drrain curren
nt Id , mA
25
Ugs = 0 mV
20
Ugs = -100 mV
15
Ugs = -200
200 mV
10
Ugs = -300 mV
5
0
Ugs = -400
400 mV
V
Respons
se (Arb. Un
nits)
f = 0.2 THz; T=300 K
250 nm GaAs FET
30
Ugs=-100 mV
25
Uggs=-200 mV
20
Ugs=-300 mV
15
Ugs=-350 mV
10
5
0
-4
0
1
2
10
Vresponse
-2
10
Drain Current Id(A)
Drain voltage
g Uds
,V
d
U a2
=
4(U gs − U th )(1 − jd / jsat )1/ 2
-3
10
jd << jsat
Symbols – experiment
Colored curves - theory
D. Veksler et al , Phys. Rev. B 73, 125328 (2006).
Michael Shur (shurm@rpi.edu) http://nina.ecse.rpi.edu/shur
37
HEMT for Resonant THz detection
d
1) M. Dyakonov and M. S. Shur, Phys. Rev. Lett. 71, 2465 (1993)
2) A. El Fatimy, N. Dyakonova, F. Teppe, W. Knap, N. Pala, R. Gaska, Q.
Fareed X.
Fareed,
X Hu,
Hu D.
D B.
B Veksler,
Veksler S.
S Rumyantsev,
Rumyantsev M.
M S.
S Shur,
Shur D.
D Seliuta,
Seliuta G.
G
Valusis, S. Bollaert, A. Shchepetov, Y. Roelens, C. Gaquiere, D. Theron,
and A. Cappy, Electronics letters, Vol. 42 No. 23, 9 November (2006)
Respon
nse ΔV, arb.. units
1)
plasma freq
p
quency (TH
Hz)
Theory:
3.0
2.5
2.0
1.5
1.0
0.5
0.0
Experiment:2)
f=0.761 THz
AlGaN/GaN
4K
20 K
70 K
-5
-4
-3
-2
-1
0
3
2
ωp =
1
0
Michael Shur (shurm@rpi.edu) http://nina.ecse.rpi.edu/shur
4π e 2 n2 d 2
k
εm
-5
5
-4
4
-3
3
-2
2
gate voltage (V)
-1
1
0
38
Resonant detection near instability threshold
0.15
δU, mV
Id=8mA
Id=22mA
0.10
f = 0.6 THz; T=300 K
GaAs FET 250 nm
0 05
0.05
0.00
-0.3
03
ω0τ <1, but ω0τeff >>1
-0.2
02
-0.1
01
00
0.0
Gate voltage Vgs, V
01
0.1
1
2τ effff
=
(
Instability increment
1
2τ
−
vd
L
)
The decrement decreases with electron velocity or drain current due to
approaching to the threshold of the plasma wave instability.
F. Teppe, W. Knap, D. Veksler, et al, Appl. Phys. Lett. 87, 052107 (2005)
Michael Shur (shurm@rpi.edu) http://nina.ecse.rpi.edu/shur
39
Homodyne detection by plasma FET: Mixing of
laser modes Heterodyne detection has a much higher
sensitivity and is usable for diffuse
0.1
reflection imaging 0.0
a)
-0.1
2.52 THz
THz laser
-0.2
Oscilloscope
S IFIR-50 FP L (1 THz – 7 THz)
Responsee, mV
Amp
plitude (a. u
u.)
Lens
1
0.1
0.0
-0.1
10.00
20.00
30.00
Time, μs
Respon
nse, mV
Chopper
-0.3
-0.4
Single mode regime
-0.5
0.1
0.0
-0.1
-0.2
-0.3
-0.4
-0.5
b) Mode mixing
0
Spectrum of laser mode beatings
0
0
1
2
3
Freq enc (MHz)
Frequency
(MH )
4
1
2
3
4
5
6
7
8
Time, ms
From Dmitry Veksler, Andrey Muravjov, William Stillman, Nezih Pala,
and Michael Shur, Detection and Homodyne Mixing of Terahertz
Gas Laser Radiation by Submicron GaAs/AlGaAs FETs, in Abstracts
of IEEE sensors Conference, Atlanta, GA, October 2007
Michael Shur (shurm@rpi.edu) http://nina.ecse.rpi.edu/shur
40
9
Comparison of THz Detection Devices (300 K)
10-11 – 10
1μs
Not-9 tunable
10-7 - 10
Schottkyy Diode
10-9
1 ms
-7
10
-8
10
-10
10
-12
10
-14
10
-16
10
-18
50
60
70
80
Frequency f, Hz
300nm
200nm
10
90
Lg=120nm
-9
-11 tunable
Not
– 10
< 10 ps
-10
10-6 – 10Tunable
< 10 ps ?
10
2
Not
tunable
-12
Pyroelectric
Plasma Wave
Detector
10
0.5
Microbolometer
Response
time
(Hz)
NEP, W/H
Hz
Detector
NEP
(W/Hz½)
Spectral density, V /Hz
Si MOS
-10
0.0
0.2
0.4
0.6
0.8
Gate voltage Vg, V
Advantages of Plasma wave detector:
El Fatimy, N. Dyakonova, F. Teppe, W.
•Band selectivity and tunability (resonant detection)
Knap,D. B. Veksler, S. Rumyantsev, M. S.
Shur, N. Pala, R. Gaska, Q. Fareed, X.
•Fast temporal response
Hu, D. Seliuta, G. Valusis, C. Gaquiere, D.
•Small
Small size (easy to fabricate matrixes/arrays)
Theron, and A. Cappy, IElec. Lett. (2006).
•Compatible with VLSI technology
Table courtesy of D. Veksler, RPI
•Broad spectral range
Michael Shur (shurm@rpi.edu) http://nina.ecse.rpi.edu/shur
41
Achieved Detector Performance
GaAs :
1 THz detection demonstrated
n = 2×1011 cm-2 L = 0.2 µm.
Detection 120 GHz - 2.5 THz
R ~ 10 - 103 V/W
GaN :
1 THz detection demonstrated
n = 2 ×1013 cm-2 & L =2 µm
Room temperature generation
(Knap et al Veksler et al (2006)
Si : 120 GHz – 3 THz detection demonstrated
10 W/Hz
NEP ~ 10-10
W/H
Michael Shur (shurm@rpi.edu) http://nina.ecse.rpi.edu/shur
42
Subwavelength Imaging: coupling of THz
radiation into transistor
Lock-in
Chopper
SR8300
λ=184 μm
FIR Laser
Polarizer
Vgs
The spatial images are obtained by
recording radiation induced drainto source voltage as a function of
to-source
the transistor position with respect
to the focused THz beam
Rload
Vds
3d NanoMax 341
Displacement 5 10 μm
Veksler, D.B. Muraviev, A.V. Elkhatib, T.A. Salama, K.N. Shur, M.S. , Plasma wave FET for sub-wavelength THz imaging,
International Semiconductor Device Research Symposium December 12-14, 2007 College Park, Maryland, USA
Michael Shur (shurm@rpi.edu) http://nina.ecse.rpi.edu/shur
43
Transistor responsivity pattern exhibits two spots of
maximum response
p
with different signs
g
Source: Terahertz gas laser SIFIR50 at 1.63 THz (184 μm)
1.00
0.75
tyy (a
nsit
1000
0.50
.u.)
0.25
400
800
0.00
0
μm
400
X
(μm
400
300
600
)
800
200
D jd = 0
Vgs = 0.45V,
200
100
Y, μm
G
S
0
-100
-200
-300
Fujitsu FHX06X
GaAs/AlGaAs HEMT
Lg=0.25μm
W=200μm
δUd, V
-2.9E-5
-2.4E-5
-1.9E-5
-1.5E-5
-9.7E-6
-4.8E-6
0
4.8E-6
9 7E 6
9.7E-6
1.5E-5
1.9E-5
2.4E-5
2.9E-5
)
600
200
Y(
Inte
Beam profile in
the focal spot:
-400
-500
-400 -300 -200 -100 0
100 200 300 400
X, μm
Veksler, D.B. Muraviev, A.V. Elkhatib, T.A. Salama, K.N. Shur, M.S. , Plasma wave FET for sub-wavelength THz imaging,
International Semiconductor Device Research Symposium December 12-14, 2007 College Park, Maryland, USA
Michael Shur (shurm@rpi.edu) http://nina.ecse.rpi.edu/shur
44
Theory
Hydrodynamic equations for
2D gas in the FET channel:
Zgd
~
~
∂v
∂v v e ∂U
+v + +
=0
∂t
∂x τ m ∂x
Ua
∂n ∂ (nv)
+
=0
∂t
∂x
Boundary conditions:
en = CU
Zgs
Ub
U ω ( 0 ) − jω ( 0 ) Z = U a , U ω ( L ) + jω ( L ) Z = U b .
We see that the response might have different signs
depending on the ratio
1
δV = −
4U gs − U th
⎛ ω0 ⎞
⎜ ⎟
⎝ω ⎠
3
|Ua |2 / |Ub |2
ω0 = (μU g )−1/ 3 (CL* )
⎛
⎞
| U a |2
| U b |2
⎜
⎟
−
⎜ (1 − j / j )1/ 2 (1 − j / j )3 / 2 ⎟
d
sat
d
sat
⎝
⎠
−2 / 3
Z ≈ − i ω L*
Veksler, D.B. Muraviev, A.V. Elkhatib, T.A. Salama, K.N. Shur, M.S. , Plasma wave FET for sub-wavelength THz imaging,
International Semiconductor Device Research Symposium December 12-14, 2007 College Park, Maryland, USA
Michael Shur (shurm@rpi.edu) http://nina.ecse.rpi.edu/shur
45
Transistor THz responsivity vs. drain
current and gate voltage
Theory:
Experiment:
1/2
3/2
Response=1/(1-Id/Isat) -α/(1-Id/Isat)
α=0, Isat=5e-2
α=0.2,
=0 2 Isat=1e-2
α=0.7, Isat=5e-3
0.6
δUd, mV
V
Re
esponse,, a.u.
2
0
Vgs=-0.63 V
Vgs=-0.45 V
Vgs=-0.30 V
Vgs=-0.15 V
Vgs= 0.0 V
0.0
-0.6
1
10
jd, ma
1
10
j , ma
d
Veksler, D.B. Muraviev, A.V. Elkhatib, T.A. Salama, K.N. Shur, M.S. , Plasma wave FET for sub-wavelength THz imaging,
International Semiconductor Device Research Symposium December 12-14, 2007 College Park, Maryland, USA
Michael Shur (shurm@rpi.edu) http://nina.ecse.rpi.edu/shur
46
THz Imaging with plasma FET
•THz image is a result of
superposition of the responses from
different parts of the transistor.
transistor
•Drain current leads to increase in
th ratio
the
ti b
between
t
negative
ti and
d
positive responses. As a result the
maximum of the response shifts in
XY plane
plane.
Sub-wavelength THz resolution is typically reached using a needle or subwavelength
l
h di
diaphragms
h
and
d optically
i ll iinduced
d
d di
diaphragms
h
Here sub-wavelength resolution might be achieved due to variation of the
responsivities driving the transistor with the drain current
Veksler, D.B. Muraviev, A.V. Elkhatib, T.A. Salama, K.N. Shur, M.S. , Plasma wave FET for sub-wavelength THz imaging,
International Semiconductor Device Research Symposium December 12-14, 2007 College Park, Maryland, USA
Michael Shur (shurm@rpi.edu) http://nina.ecse.rpi.edu/shur
47
Grating Gate Devices and FET Arrays
•grating-gate of a large area serves
as an aerial matched THz antenna
•due to constructive interference
between the gates the plasmons
in all FET-units are excited in phase
Absorb
bance (AU)
0.25
0.20
0.15
0.10
0 05
0.05
0.00
LS=0.1μm
LS=0.2μm
LS=0.3μm
LS=0.5μm
•higher-order plasmon resonances (up to 7th order)
0
1
2
3
can be
b effectively
ff ti l excited
it d with
ith a slit-gating
lit ti gate
t
Frequency
due to strong electric-field harmonics generated in slits
4
5
6
(THz)
Plasmon absorption in a slit-grating gate device is 103 times
stronger
t
th
than in
i array off non-interacting
i t
ti
FET units
it
V. Popov, M. Shur, G. Tsymbalov, D. Fateev, IJHSES, September 2007
Michael Shur (shurm@rpi.edu) http://nina.ecse.rpi.edu/shur
48
7
Electronic island at the surface of
semiconductor grain in pyroelectric matrix
Inversion electron and hole islands at the surface of
pyroelectric grain in semiconductor matrix
Pyroelectric
Po
Po
Semiconductor
Semiconductor
Hole inversion island
Pyroelectric
Electronic island
Electronic inversion island
Control by external field – Zero dimensional Field Effect (ZFE)
After V. Kachorovskii and M. S. Shur, APL, March 29 (2004)
Michael Shur (shurm@rpi.edu) http://nina.ecse.rpi.edu/shur
49
Terahertz oscillations
2D island might oscillate as a whole over grain surface.
The oscillations can be exited by AC field perpendicular to Po
Oscillation frequency
ω0 =
4π eP0
( ε + 2εp ) mR
MOVABLE QUANTUM DOTS (MQD)
Oscillation frequency is of the order of a terahertz
ω0π/2~ 1 THz to 30 THz
CAN SWITCH OR SHIFT FREQUENCY
BY EXTERNAL FIELD OR BY LIGHT
After V. Kachorovskii and M. S. Shur, APL, March 29 (2004)
Michael Shur (shurm@rpi.edu) http://nina.ecse.rpi.edu/shur
50
Conclusions
•Silicon penetrated THz range
•C
C3 contacts reduce parasitics in THz transistors
•Transport is ballistic in submicron transistors, and the
physics is very different
•Ultra short channel transistors support plasma waves in
THz range with the channel acting as a resonance cavity
•Plasma waves can be used for detection and generation of
THz radiation
•A plasma wave FET can achieve THz resolution at
nanometer scale
ays o
of THz p
plasma
as a wave
a e ttransistors
a s sto s p
promise
o se x1,000
,000
•Arrays
increase in performance
Michael Shur (shurm@rpi.edu) http://nina.ecse.rpi.edu/shur
51
I am grateful to my THz colleagues for their
hard work, inspiration, and contributions
Dr. Dyakonova and
y
Prof. Dyakonov
Dr. Deng
Dr. Muraviev
Dr. Veksler
Prof. M. Ryzhii
Dr. Satou
Dr. Kachorovskii
Dr. Dmitriev
Dr. Levinshtein
Prof. Pala
Prof. Zhang
Dr. Popov
Michael Shur (shurm@rpi.edu) http://nina.ecse.rpi.edu/shur
Dr. Knap
Prof. V. Ryzhii
T. Elkhatib
Dr. Rumyantsev
Dr. Stillman
Prof. Xu
52
Acknowledgment
This work has been supported
by NSF, ONR, and DARPA (MTO)
Michael Shur (shurm@rpi.edu) http://nina.ecse.rpi.edu/shur
53