Terahertz Plasma Oscillations in semiconductor ...web.nano.cnr.it/scuolafotonica2013/wp-content/uploads/2013/06/Kn… · • Plasma resonances can reach THz range for sub- micron

Terahertz Plasma Oscillations in semiconductor

Nanostructures: Basic Physic and Applications

W. Knap, M.Dyakonov, D.Coquilat, F.Teppe, N.Dyakonova

Université Montpellier 2, France and UNIPRESS Warsaw Poland

J.Lusakowski, M.Sakowicz,

University of Warsaw and ITE Poland

S.Rumyantsev & M.Shur

RPI – Troy NY USA

M.Vitello, A. Tredigucci

SNS – Pise Italy

Plasma waves sound Waves &Transistors

Detection & Imaging

Current research and unresolved problems

Outline Plasma waves &Transistors

Plasma waves and dimensionality

Fiel Effect Transistors

Plasma waves in the transistors

Well establised results and apllications

Regimes of detection

Resonant detection

Non-resonant detection


Emission

Temperature

Resonat dreams with graphene

Circular polarisation

THz communication


3D - +

E

I

E

2D

p

k

p

k

d 2D

gated

p

k

2DEG

2DEG

m

ne Dp

0

32

km

ne Dp

0

22

2

m

dnes

sk

D

p

0

22

Standing Longitudinal Waves in the tube

Different modes

pipe-waves.html

Musical wind instrument Analogy ( Air and Plasma Waves Comparison)

Parameter Sound 2D plasma

Dimension 0.1-1 m 0.1-1 µm

Speed of waves (s) 300 m/s 106 m/s

Frequency (s/L) 0.3kHz-3kHz 1THz-10THz

Appl. Phys. Lett. 67, 1137 (1995) M. Dyakonov et al.

BETTER THEN ACOUSTIC INSTRUMENTS …….Voltage tunable

Plasma waves velocity in 2DEG gated gas

« Voltage tuneability»

k

d 2D

gated 2DEG

m

eUs

dC

CUn

m

dnes

sk

D

D

p

0

2

0

22

Frequency of the plasma oscillations

Vg

S D

L

« Voltage tuneability»

Lk 4__,2

m

eUs

24.006.0

1

11.0

m

VU

µmLTHzTHzf p 0.46.0

m

eU

Lf p

4

1

sk

Basic mode n=1, ..3,5,7

Dreams of plasma waves resonances

(high frequency and short transistors)

Short gate: L << sτ

1 Plasma waves are weakly

damped

S D

L

Vg

Experimental observations of plasma waves in 2DEG

P. J. Burke et al. APL, 76 , 745 (2000)

GaAs/AlGaAs, gated 2DEG

L=360µm KTVsmµ 1~_/330 2

S. J. Allen, D. C. Tsui, and R. A. Logan, PRL, 38, 980 (1977)

D. C. Tsui, E. Gornik, and R. A. Logan, Sol. St. Comm, 35, 875 (1980)

Can Plasma Waves Exist in main Semiconductor FETs???

For GaAs ( 1 THz) n = 21012 cm-2 & L = 600nm.

For GaN (1 THz) n = 2 1013 cm-2 & L =1000nm

For Si (1 THz) n = 2 1012 cm-2 & L =300nm

!!!!!!!!!!!!!!!NANOTECHNOLOGY!!!!!!!!!!!!!!!

_*/~??_1__ LmnfTHzfrequencyreaching s

2.1~ / 6000~

2.1~ / 1500~

4.0~ / 500~

2

2

2

GaAsGaAs

GaNGaN

SiSi

Vscm

Vscm

Vscm

???1__300__1__ THzforKatreaching

Conclusions on plasma

• Plasma oscillations in gated 2DEG have acoustic like

behaviour

• They were observed in big devices in cryogenic

temperatures

• Plasma resonances can reach THz range for sub-

micron devices

Field Effect Transistors

Carrier density regulated by the electric field of the gate

conductive layer

metal

semiconductor

isolator S D

G


MOSFET

2DEG CREATION 2DEG DEPLETION

2DEG

gate

HEMT

Vg = 0 -> n=0

Gate

Barrier Channel

2DEG

Vg = 0 -> n≠0

2DEG

Transfer Characteristics

-0.5 0.0 0.5 1.0 1.5

0.0

0.2

0.4

0.6

0.8

1.0

1.2

1.4

MOSFET

Uds

= 0.1 V

Dra

in C

urr

en

t, I

ds (

mA

)

Gate Voltage, Ug (V)

-1.5 -1.0 -0.5 0.0

0.0

0.2

0.4

0.6

0.8

HEMT

Dra

in C

urr

en

t, I

ds (

mA

)

Gate Voltage, Ug (V)

Uds

= 1 mV

2DEG CREATION 2DEG DEPLETION

Threshold Voltage, VTH -> n = 0

THg VVCne

ETH Zurich

100 nm gate AlGaN/GaN on silicon

HEMT with a 1 µm source-drain

separation

S D

G

APL 80, 246, (2002)


S G D

Cross section of a MOSFET

(a) Transmission electron micrograph

(b) Phase image obtained by

electron holography

MOSFET HEMT

Plasma waves excitation by THz radiation

THz radiation couples to the transistor by antennas – it can

be represented as AC source between two electrodes

Regimes of plasma waves (high frequency)

Short gate: L << sτ Long gate: L >> sτ

sl Characteristic damping length:

1 Plasma waves are weakly damped

Overdamped oscillations

(low frequency/mobility ,300K )

// geff µUsl

“x” distance normalized by “ damping length”

1

Transistor basic ideas

• Two main families of transistors –of FETs

• Basic FET Characteristics – transfer

• Plasma excitations can have a form of travelling

waves or overdamped/dacaying oscillations (300K)







Resonant detection



Emission

Temperature



THz communication







Resonant detection



Emission

Temperature



THz communication

Rectification of THz radiation in FETs

• Vgs: Source-Gate bias

• Ua: irradiation induced

ac voltage

• ΔU: dc photoresponse Vgs

Ua

ΔU

G D S

Lg

THz

FET , cw

: dc

!!Nonlinearity – THz modulates simultaneously

!!carrier density and drift velocity!!

Experimental Setup

Devices

50m

Gate Source Drain

(c)

2mm

(b)

R. Tauk, F. Teppe, S. Boubanga, D. Coquillat, W. Knap, Y.M. Meziani

C. Gallon, F. Boeuf, T. Skotnicki, C. Fenouillet-Beranger, D. Maude, S. Rumyantsev, M.S. Shur Plasma wave detection of terahertz radiation by

silicon field effects transistors: responsivity and noise equivalent power, accepted to APL

0.7THz /2=214m

Diffraction

limited spot:

214X214m

I ds (

A)

Pho

tore

sponse D

U (

mV

)

Gate Voltage Vgs (V)

Sakowicz et al.

JAP, 2011

1)Experimental proofs of plasma waves existence

2)Can we make a resonators and see resonant

votage tunable THz detection ??

3) Ovedamped Plasma and THz imaging @ 300K

Regimes of plasma waves (high frequency)

Long gate: L >> sτ

sl Characteristic damping length:

1 Plasma waves are weakly damped

Vg

S D

L

2DEG in Magnetic Field

http://www.warwick.ac.uk/~phsbm/2deg.htm

CYCLOTRON ORBIT

*m

eBc

ENERGY QUANTIZATION

cnEE 210

Cyclotron Resonance

0 1 2 3 4 5 6 7 8 9 10 110

10

20

30

40

50

En

erg

y (

me

V)

Magnetic Field, B (T)

c *m

eBc

Schubnikov – de Haas Oscillations

Be

hn

Bm

e

shA

A

q

1cos

1exp

*0

0 2 4 6 8 10 12

-0.2

0.0

0.2

0.4

0.6

0.8

1.0

1.2

1.4

1.6

1.8

HEMT

Ug = -2V

Ug = -1V

Re

sis

tan

ce

(a

.u.)

Magnetic Field (T)

Ug = 0V

n

increases

0 2 4 6 8 10 12 14

0,0

0,5

1,0

1,5

2,0

2,5

3,0

3,5

4,0

=10

=9

=8

=7

- Fig. 2-

50 mK

1.5 K

Rxx

, Rxy

(k

)

Magnetic Field (T)

0 1 2 3

-0,10

-0,05

0,00

0,05

0,10T

D = 3 K

(Rxx-R

0)/R

0

Magnetic Field (T)

Frassinet et al. Appl. Phys. Lett. 77,2551(2000)

Quantum Hall Effect and SdH Studies

22 )(skc

2

2

1

c

sk

When ωc > ω k is imaginary and

plasma waves can not propagete

Plasma waves and Cyclotron resonace

sk

THz rectification by In GaAs FET in magnetic fields

0.0 0.5 1.0 1.5

0

1

Vg = 0 V experiment

B/Bc

Ph

oto

resp

on

se, a

. u

0.0 0.5 1.0 1.5-1.0

-0.5

0.0

0.5

1.0

Vg = - 0.1 V experiment

B/Bc

Ph

oto

resp

on

se, a

. u

0.0 0.5 1.0 1.5

-5

-4

-3

-2

-1

0

1

2Vg = 0.1 V

Ph

oto

resp

on

se (

Arb

.Un

its)

B / BC

0.0 0.5 1.0 1.5-8

-6

-4

-2

0

2

4

6

8

Vg = - 0.125 V

Ph

oto

resp

on

se (

Arb

. U

nit

s)

B / BC

THz rectification by In GaAs FET in magnetic fields

experiment and theory

Exp S. Boubanga-Tombet et al.

APL 2009

0,0 0,5 1,0 1,5

-1

0

1

-2

-1

0

1

Ph

oto

resp

on

se,

a.

u

(a)

Vg = 0.1 V experiment

theory

B/Bc

N = 5.25

0,0 0,5 1,0 1,5-1

0

1-1

0

1

Ph

oto

resp

on

se,

a.

u

(b)

Vg = - 0.125 V

B/Bc

experiment

theory

N = 2.3

Theory M.Lifshits and M.I.

Dyakonov

PRB –Rapid Com 2009





Dreams of plasma waves resonances

(high frequency and short transistors)

Short gate: L << sτ

1 Plasma waves are weakly

damped

S D

L

Vg




ac voltage


Ua

ΔU

G D S

Lg

THz

FET , cw

: dc



First -Resonant Detection 0.6THz ~1 Experiment ,250nm GaAs FET (Appl Phys Lett 2001)

The gate voltage – tunes carrier density – plasma frequency …to resonance

Resonant and “voltage-tunable” terahertz detection

in InGaAs/InP nanometer transistors

A. El Fatimy et al, APL 89, 131926, 2006

The calculated plasmon frequency as a function of the gate voltage for

Shown by the solid line SQRT dependece .

The error bars correspond to the linewidth of the measured plasmon

resonance peaks.

Vg (V)

-0,4 -0,3 -0,2 -0,1 0,0

800,0µ

1,2m

1,6m

2,0m

2,4m

f=1,8 THz

f=3,1 THz

f=2,5 THz

T= 10KInGaAs

Lg = 50 nm

Gate voltage Vg,V

Re

sp

on

se

DV

ard

, u

nit

s

Resonant Detector & Quality factor InGaAs

Line width : ~ 3 ???? µ = 36 000 cm2/V.s ?? ~ 13??

-0,4 -0,3 -0,2 -0,1 0,01T

2T

3T

4T

5T

6T

7T

Gate voltage Vg,V

Pla

sm

a F

req

ue

nc

y (

TH

z)

A. El Fatimy et al. APL, 89, 131926 ,(2006)

Resonances are wider than expected…???

Discussion on plasma modes Broadening

• W/L ~ 100

• roughness on the gate bounderies

M.I. Dyakonov Semiconductors, 2008, Vol. 42, No. 8

Dyakonov-Shur theory

geometry

Experimental geometry

S D

Only longitudinal

modes

All modes are permitted

Top view Top view

L

w

L

W S D

Additional broadening mechanism

ky

ω

y

x M. Dyakonov and M. Shur, IEEE

Vol. 43, No. 3, (1996)

Samples - Multi-Channel InGaAs

HEMTs

I-V Characteristics at 20 K

L = 400 nm

W = 200 nm

Wgr = 300 nm

S. Boubanga-Tombet et al. APL, 92, 212101, (2008)

A. Shepetov et al . APL, 92, 242105, (2008)

-450 -400 0 20 40 60 80 100

8

10

12

14

16

18

20

22

8

6

4

2

(b)

Vds

(mV)

Qu

ality

Facto

r

Vds

= 100 mV

Vds

= 50 mV

Vds

= 10 mV

Vds

= 0 mV

Rep

on

se (

Arb

. U

nit

s)

Vgs

(a)

Detection governed by dc current in Multi-Channel FET

Dc current leads to a strong shrinking of the line : From 58 GHz at

Vds = 0 V to 26 GHz at Vds = 100 mV

Incoming

frequency = 0.54 THz

T = 10 K

L

Vdsd

S. Boubanga-Tombet et al. APL, 92, 212101, (2008)

µ = 11 m2/V.s

DC current strongly reduce plasma wave damping





300K - Overdamped plasma oscillations

1

S D

L

Vg

/sl Characteristic length:




ac voltage


Ua

ΔU

G D S

Lg

THz

FET , cw

: dc



0.6 THz imaging with InGaAs HEMT – 300K

25 mm25 mm

0.6 THz imaging - collaboration with University of Frankfurt

A. Lisauskas, W. von Spiegel, S. Boubanga, A. El Fatimy, D. Coquillat, F. Teppe,

N. Dyakonova, W. Knap, and H. G. Roskos, Electr. Lett. 44, 408 (2008).

Imaging at 1.6 THz with a single FET

THz

Object under test

GaAs nanotransistor

molecular THz laser

2 4 6 8 10 12 14

2

4

6

8

10

12

14

16

18

0,017

0,033

0,065

0,13

0,26

0,51

1,0

2 4 6 8 10 12 14

2

4

6

8

10

12

14

16

18

0,017

0,033

0,065

0,13

0,26

0,51

1,0

Results from Vilnius ( collaboration with Montpellier) (2008).

I ds (

A)

Pho

tore

sponse D

U (

mV

)


Detection of terahertz radiation by Si field effects transistors 300K

0.0 0.2 0.4 0.6 0.80

50

100

150

0 100 200 3000.0

0.2

0.4

0.6

0.8

1.0

120nm

200nm

Lg=300nm

Re

sp

on

siv

ity,

V/W

Gate voltage Vg, V

Gate length Lg, nm

Resp

on

siv

ity, arb

. u

nit

s

f=0.7THz

AC voltage U1 and DC signal U2

Dependence of the ac voltage U1/Ua at ωt =2πn

and of the dc photoinduced voltage U2/ΔU

on the distance from the source x for a long gate

THz detection & Signal to noise ratio in Si-MOSFETs

Appl Phys. Letters 2004 & 2006

50 60 70 80 9010

-18

10-17

10-16

10-15

10-14

10-13

10-12

10-11

10-10

10-9

noise= 4kTR

Signal

Spectr

al density, V

2/H

z

Frequency f, Hz

NEP=10pW/Hz0.5

Lg=120nm. Vg=0.3V

F=700GHZ

300K CMOS THz detectors -Fast, sensitive & INTEGRABLE in MATRIXES!!!

-For 300K price effective focal plane arrays -Fast enough for THz communication

Sampling

frequency (MAX)

NEP (pW/Hz0.5)

Golay Cell ~20Hz 100

Pyroelectric <10KHz 1000

Schottky Diodes <20GHz 10

Microbolometers <1MHz 10

Si transistors 30GHz or higher 10

THz Imaging with

Si-MOSFET Detectors

0.13µm CMOS

"Broadband terahertz imaging with highly sensitive

silicon CMOS detectors,"

F.Schuster et al

Optics Express, vol. 19, pp. 7827-7832, (2011)

Laser Focus World, vol. 47(7), pp. 37–41, (2011)

20 40 60

20

40

60

80

100

120

140

160

180

X Axis (mm)

Y A

xis

(mm

)

0

4.50m

9.00m

13.5m

18.0m

22.5m

27.0m

31.5m

36.0m

40.5m

45.0m

Imaging with MOSFET –0.3THz

“!!!!Cutting Edge Technology!!!”

0 10 20 30 40 50 60 700

10

20

30

40

50

60

70

80

90

X Axis (mm)

Y A

xis

(m

m)

0

0.02100

0.04200

0.06300

0.08400

0.1050

0.1260

0.1470

0.1680

0.1890

0.2100

Imagerie THz avec un Transistor MOSFET

Radiation : 0.3 THz (= 1 mm),

Puissance 2 mW

10 ms/point Scan-Time: qq min

Measurement Imaging at 300GHz, tree leaves

225x600 scanned points

PANASONIC GaN detector 2011

150 µm

200 µ

m

Other groups – Competitors/Collaborators

in Si CMOS Imaging

• Goethe University of Frankfurt group of

Prof.Roskos

• Dallas University /Texas Inst. USA

Ken.O

• Wuppertal University

Prof. Pfeifer

First 1000 pixel Si CMOS

camera

( February 2012)

(German –French project)

End of The Second Part










Magnetic field and plasma

Resonant detection



Emission

Temperature



THz communication






Magnetic field and plasma

Resonant detection



Emission

Temperature



THz communication

1) Can we have THz detection with Graphene??

2) Can we enhance nonresonat THz detection while

lowering temperature

3) THz polarization measurements with HEMTS

4) Can FETs be THz emitters???

Frequency of the plasma oscillations !!!300K!!! Vg

S D

L

24.006.0

1

11.0

m

VU

µmL

THzTHzf p 0.46.0

m

eU

Lf p

4

1

1

!!Only When Plasma waves are weakly damped!

THz detection by Graphene transistors

L. Vicarelli,1 M.S. Vitiello,1 D. Coquillat,2 A.C. Ferrari,3 W. Knap,2

M. Polini,1 V. Pellegrini,1 and A. Tredicucci1

Common project : Pise1, Montpellier2, Cambridge3

-1 0 1 2 3

-2

-1

0

1

2

Monolayer

Graphene

1/

d/d

Vg (

1/V

)

Gate Voltage (V)

CN

P

-1 0 1 2 31x10

-5

2x10-5

3x10-5

4x10-5

5x10-5

6x10-5

Monolayer

Graphene

(

1/O

hm

)

Gate Voltage (V)

CN

P

-1 0 1 2 3-1m

-500µ

0

500µ

1mP

hoto

response X

(V

)

Gate Voltage (V)

Monolayer

Graphene

CN

P

Electrons

Holes

MOTIVATION!!!

??300K RESONANCES

FOR SELECTIVE GATE TUNABLE

DETECTION AND EMISSION ???

NATURE MATERIALS DEC 2012






I ds (

A)

Pho

tore

sponse D

U (

mV

)


Sakowicz et al.

JAP, 2011

slide 72

1.0 1.2 1.4 1.6 1.8 2.00

10

20

30

40

50

T = 5 K

T = 10 K

T = 30 K

T = 50 K

T = 75 K

T = 100 K

T = 125 K

T = 175 K

T = 275 K

Photo

response (

mV

)

Vg (V)

Si

0.01

0.1

T = 5 K

T = 10 K

T = 30 K

T = 50 K

T = 75 K

T = 100 K

T = 125 K

T = 175 K

T = 275 K

Id (

µA

) (Klimenko et al

JAP 2012)

kTU

signalTHz

/1

_??

D

slide 73

10 1001

10

GaAs

GaN

Si

DU

max, m

V

T, K (Klimenko et al JAP 2012)

bandimpurityconstU

KabovediffusionekTU

where

UUandUU

____???_*

30_____/*

*/1____*/exp_

D

Physical limitations – U*

subthreshold

Klimenko et al Journal of Applied Phys 2012






J. Appl. Phys. 111 124504 (2012)

theory M.Dyakonov J. Appl. Phys.

(2013)

Linear polarization detection

Source drain voltage from FET at 800GHz






Shallow water analogy for a ballistic field effect transistor: New

mechanism of plasma wave generation by DC current

M. Dyakonov and M. S. Shur, Phys. Rev. Lett. 71, 2465 (1993)

Plasma Waves FET as THz Emitter

Introduction

Instability and THz generation

This mechanism of plasma wave generation is similar to sound generation in a whistle and wind musical instruments:

Ingredients:

a) Resonator

b) Asymmetric boundary conditions

Instability - Threshold

Plasma waves instability &Emission-

Threshold like - phenomena – laser analogy

2 2

0 0

0

exp( )

ln2

A t

s v s v

Ls s v

M. Dyakonov, M. Shur, Phys. Rev. Lett. 71, 2465, (1993)

0v s

1 0.5 0

83

Cryogenic THz Spectrometer

W. Knap et al.,

Rev. Scient. Instr. 63, 3293

(1992)

0 2 4 6 8 10 120

2

4

6

8

10

12

14

16

18

20

0 1 2 30.0

0.5

1.0

0.2 0.4 0.6 0.8

0.4

0.6

0.8

1.0

InGaAs-HEMT

f (T

Hz)

Usd

(V)f (THz)

Em

iss

ion

(a

.u.)

Em

issio

n In

ten

sity (

a.U

.)

Detection Frequency (THz)

InSb-bulka)

b)

APL-2004

Threshold behaviour in the magnetic field

0.0 0.2 0.4 0.6 0.810

1

102

103

104

105

Em

issio

n in

ten

sity

(arb

. u

.)

UDS

( V )

B=0

B=1

B=2

B=3

B=4

B=5

B=6

N. Dyakonova et al. J. Appl. Phys. 97, 114313 (2005),

The shift of the threshold voltage - the magnetoresistance of the ungated

http://www.cnrs.fr/

0 1 2 3 4 5 6 7 8 9 100,0

0,1

0,2

0,3

0,4

0,5

0,6

Lg= 50 ,60 ,80 ...100nm W = 20µ mE

mis

sio

n,

a.u

.

f , T H z

Transistors of different gate length

• Vg dependence is not observed

• Spectra is broad and there is no strong dependence on L

Emission spectra

T = 4.2K

Deep/shallow water analogy -

GateSource Drain

3D gas 3D gasUngated2D gas

Gated 2D gas

Deep WaterWaves

Deep WaterWaves

Shallow WaterWaves

Discussion on plasma modes Broadening

• W/L ~ 100

• roughness on the gate bounderies

M.I. Dyakonov Semiconductors, 2008, Vol. 42, No. 8

Dyakonov-Shur theory

geometry

Experimental geometry

S D

Only longitudinal

modes

All modes are permitted

Top view Top view

L

w

L

W S D

Additional broadening mechanism

ky

ω

y

x M. Dyakonov and M. Shur, IEEE

Vol. 43, No. 3, (1996)

So

urc

e

Dra

in

Gate

So

urc

e

Dra

in

Gate

Shallow , deep and white water instabilities

Field Plate GaN transistor for THz emission

1,5 3,0 4,50,0

0,1

0,2

0,4

0,5

0,6

0,7

0,8

0,9

1,1

Vg=-4VNo

rma

lized

sig

na

l (a

u)

Frequency (THZ)

Vg=0

Fourier Transform analysis

GaN/alGaN 200nm transistor

T=300K Vd=8V

0 200 400 600 800 10004

6

8

10

12

14

Sig

nal,

u.a

Wavenumber, cm-1

0 1 2 3 4 5 6 7 80

1

2

3

4

5

6

(b)

-4 -3 -2 -1 01.6

1.8

2.0

2.2

2.4

2.6

FW

HM

, T

Hz

Vgs, Volt

Vgs=0 V

Em

issio

n,

u.a

Frequency, THz

0.75 THz

2.1 THz

Vgs=-3.5 V

Vds =4V (a)

THZ emission from GaN/AlGaN

-5.0 -4.5 -4.0 -3.5 -3.0 -2.5 -2.0 -1.5 -1.0 -0.5 0.0 0.5

0.5

1.0

1.5

2.0

2.5

0.5

1.0

1.5

2.0

2.5

F

req

ue

ncy, T

Hz

Ugs, V

Lg=250nm

Lg=150nm

2DEG at AlGaN/GaN

10 100

2x1012

3x1012

4x1012

5x1012

6x1012

sample A

sample B

sample C

nH

all (c

m-2)

Temperature (K)

103

104

105 GaN/AlGaN

Mo

bili

ty (

cm

2/V

s)

Skierbiszewski et. al. Phys Stat Sol (b) 2004

Skierbiszewski et. al. Appl. Phys Lett. 2005

HIGH MOBILITY at 300K :

2500 cm2/Vs

World record!

Important for device

performance

UNIPRESS

THz Source Based on GaN

THZ Emission ( UNIPRESS – UM2)

L = 75 µm

W =

30

µm

Multi GaInAs HEMT

Emitters






1)Plasma and dimensionality (THz in gated 2DEG)

2)FET transistors and THz plasma oscilations(nano)

3)Experimental proofs of existence (f(B))


votage tunable THz detection ?? (Yes …broad &LT)


votage tunable THz emission ?? (Yes ….broad)

6)Ovedamped Plasma and THz 300K imaging with Si

MOSFETS (Leading current application)

7) Current and Future Research

( 300K Res plasma in Graphene for detectors

Polarization, GaN THz emitters )

Documents

Terahertz Plasma Oscillations in semiconductor ...web.nano.cnr.it/scuolafotonica2013/wp-content/uploads/2013/06/Kn… · • Plasma resonances can reach THz range for sub- micron