march 2011 doc.: ieee 802.15-15-11-0214-00-0thz … objective and make possible the demonstration of...

doc.: IEEE 802.15-15-11-0214-00-0thz

Submission

March 2011

J. Mateos, University of Salamanca, SpainSlide 1

Project: IEEE P802.15 Working Group for Wireless Personal Area NProject: IEEE P802.15 Working Group for Wireless Personal Area Networks (etworks (WPANsWPANs))

Submission Title: Room temperature THz sources and detectors with semiconductor nanodevices, the ROOTHz projectDate Submitted: 11 March 2011Source: Javier Mateos, Universidad de SalamancaAddress: Facultad de Ciencias, Pza. Merced s/n, 37008 Salamanca, SpainVoice: +34 923 294436, FAX: +34 923 294584, E-Mail: [email protected]

Abstract: ROOTHz is a 3 year project funded within the European 7th Framework Program thataddresses the fabrication of room temperature, continuous wave, compact, tunable and powerful T-ray sources (at low cost, if possible). For this sake we propose to exploit THz Gunn oscillations in novel (narrow and wide bandgap) semiconductor nanodevices, which have been predicted by simulations but not experimentally confirmed yet. The fabrication of THz detectors with the same technology will complement this objective and make possible the demonstration of a simple THz detection/emission subsystem.Purpose: Dissemination of the ROOTHz project objectives and achievements

Notice: This document has been prepared to assist the IEEE P802.15. It is offered as a basis for discussion and is not binding on the contributing individual(s) or organization(s). The material in this document is subject to change in form and content after further study. The contributor(s) reserve(s) the right to add, amend or withdraw material contained herein.Release: The contributor acknowledges and accepts that this contribution becomes the property of IEEE and may be made publicly available by P802.15.

doc.: IEEE 802.15-15-11-0214-00-0thz

Submission

March 2011


Room temperature THz sources and detectors with semiconductor nanodevices, the ROOTHz project

Javier MateosUniversity of Salamanca, Spain

doc.: IEEE 802.15-15-11-0214-00-0thz

Submission

March 2011


Introduction: Importance of THz

ROOTHz Project

Self Switching Diodes (SSDs)

Slot Diodes

Conclusions

OutlineOutlineOutlineOutline

doc.: IEEE 802.15-15-11-0214-00-0thz

Submission

March 2011


Image of sea surface temperature (European Space Agency)

THz radiation can penetrate poor weather, dust and smoke far better than infrared or visible systems.

SatelliteSatellite TelemetryTelemetryAeronauticsAeronautics: :

guidanceguidance andand landinglanding

Importance of THz: TImportance of THz: T--raysrays

doc.: IEEE 802.15-15-11-0214-00-0thz

Submission

March 2011


THz radiation can penetrate organic materials without ionizing.

Readily absorbed by water: distinguish between materials with varying water content

Medical Medical imagingimaging

Courtesy of Teraview Courtesy of Teraview

Skin Skin CancerCancer DetectionDetection


doc.: IEEE 802.15-15-11-0214-00-0thz

Submission

March 2011


THz radiation can penetrate dielectrics such as windows, paper, clothing and in certain instances even walls


doc.: IEEE 802.15-15-11-0214-00-0thz

Submission

March 2011


WeaponWeapon oror ExplosiveExplosive DetectionDetection ((metallicmetallic oror non non metallicmetallic))

Courtesy of Qinetiq Courtesy of ThruvisionCourtesy of Qinetiq

Importance of THz: TImportance of THz: T--raysraysTHz radiation can penetrate dielectrics such as windows, paper, clothing

and in certain instances even walls

doc.: IEEE 802.15-15-11-0214-00-0thz

Submission

March 2011


WeaponWeapon oror ExplosiveExplosive DetectionDetection ((metallicmetallic oror non non metallicmetallic))



doc.: IEEE 802.15-15-11-0214-00-0thz

Submission

March 2011


NonNon--destructivedestructive testingtesting::lntegratedlntegrated CircuitCircuit PackagePackage lnspectionlnspection

Courtesy of Teraview



doc.: IEEE 802.15-15-11-0214-00-0thz

Submission

March 2011


THz radiation can be used to identify spectral fingerprints of explosives, narcotics, or active pharmaceutical ingredients


doc.: IEEE 802.15-15-11-0214-00-0thz

Submission

March 2011


ELECTRONICSPHOTONICS THz Gap

All-optical sources

• Mixing lasers with close frequencies• Excitation of semiconductors orsuperconductors with femtosecond laser pulses• Quantum cascade lasers

Bulky and expensive equipment

The THz GapThe THz Gap

Semiconductor Semiconductor NanodevicesNanodevices for for Room Temperature THz Room Temperature THz Emission and DetectionEmission and Detection

((ROOTHzROOTHz Project)Project)

doc.: IEEE 802.15-15-11-0214-00-0thz

Submission

March 2011


Quantum cascade lasers (QCL)

QCL at cyogenic T

Frequency multipliers_ Other electronic devices:

amplifiers, RTDs, IMPATT and Gunn diodes

500 GHz – 2 THz

The THz GapThe THz Gap

Semiconductor Semiconductor NanodevicesNanodevices for for Room Temperature THz Room Temperature THz Emission and DetectionEmission and Detection


doc.: IEEE 802.15-15-11-0214-00-0thz

Submission

March 2011



ROOTHz Project


Slot Diodes

Conclusions


doc.: IEEE 802.15-15-11-0214-00-0thz

Submission

March 2011


• Funded under: 7th FWP (Seventh Framework Programme)• Area: FET Open (ICT-2007.8.0)• Project Reference: 243845• Total cost: 2.1 M€• EU contribution: 1.57 M€• Execution: from 1st January 2010 to 31st December 2012• Duration: 36 months• Web: www.roothz.eu

Semiconductor Semiconductor NanodevicesNanodevices for Room for Room Temperature THz Emission and DetectionTemperature THz Emission and Detection


doc.: IEEE 802.15-15-11-0214-00-0thz

Submission

March 2011


Semiconductor Semiconductor NanodevicesNanodevices


Slot Diodes (Ungated HEMTs)

Barrier

OhmicContact

OhmicContact

Buffer

Channel

Cap LayerTop View

CurrentInsulating Trenches

Contact

Contact

NarrowNarrow BandgapBandgapSemiconductors (NBG):Semiconductors (NBG):

InGaAsInGaAs//AlInAsAlInAsInAsInAs//AlSbAlSb

InSbInSb//AlInSbAlInSb

Wide Wide BandgapBandgapSemiconductors (WBG):Semiconductors (WBG):

GaNGaN//AlGaNAlGaN

doc.: IEEE 802.15-15-11-0214-00-0thz

Submission

March 2011


Institut d’Electronique Microélectroniqueet de Nanotechnologie

Lille, France

The University of ManchesterManchester, UK

Chalmers University of Technology Gothenburg, Sweden

PartnersPartners

Coordinator:University of Salamanca

Salamanca, Spain

doc.: IEEE 802.15-15-11-0214-00-0thz

Submission

March 2011



ROOTHz Project


Slot Diodes

Conclusions


doc.: IEEE 802.15-15-11-0214-00-0thz

Submission

March 2011


Self Switching Diodes (Self Switching Diodes (SSDsSSDs))

1 µm

V (V)-3 -2 -1 0 1 2 3

Cur

rent

( A

)

-0.5

0.0

0.5

1.0

1.5

2.0

2.5

3.0

W approx. 60 nmW approx. 70 nm

– +

+ + + + +

+ + + + +V>0, channel open

– – – – –V<0, channel closed

–+

– – – – –

InPInP

InP - substrate

InGaAs

doping

InGaAs channel

nanochannel

doc.: IEEE 802.15-15-11-0214-00-0thz

Submission

March 2011


Optimum geometry for the onset of Gunn

oscillations

Tuneable threshold voltage from almost zero to more than ten volts by adjusting

the channel width

Simple technological process: etching of

insulating trenches on a semiconductor surface

Easy downscaling and parallelization: THz

operation can be obtained


doc.: IEEE 802.15-15-11-0214-00-0thz

Submission

March 2011


• THz Detection: non-linear I-V characteristics Use of NBG materials (Room Temperature ballistic transport) for increased sensitivity and broadband

• THz Emission: Gunn Effect in InGaAs, and GaN! Use of WBG materials for increased power

• Planar geometry (and antennas) allow for a better coupling

• Parallelization for enhanced performances (and correct thermal management)


doc.: IEEE 802.15-15-11-0214-00-0thz

Submission

March 2011



ROOTHz Project


Slot Diodes

Conclusions


SSDs as THz detectors SSDs as THz emitters

doc.: IEEE 802.15-15-11-0214-00-0thz

Submission

March 2011


SSDsSSDs as THz detectors: Experimentsas THz detectors: Experiments

0.1 1 10 1001

10

100

V out (

mV)

Freq. (GHz)

Ibias = 6 A Ibias = 0 A

300 K, 75 mV/mW @110 GHz

C. Balocco, A. M. Song, M. Aberg, A. Forchel, T. González, J. Mateos et al., Nano Lett. 5, 1423 (2005)

2.5 THz 1.3 THz

C. Balocco, M. Marshall, N. Q. Vinh and A. M. Song, J. Phys.: Condens. Matter 20, 385203 (2008)

10 K, operative in the THz range(drop in the response above 70 K) 6 diodes in parallel

18 diodes in parallel

doc.: IEEE 802.15-15-11-0214-00-0thz

Submission

March 2011


SSDsSSDs as THz detectors: Monte Carlo Simulationsas THz detectors: Monte Carlo Simulations

LC=250 nm

WC=50 nm

WV=20 nm

WH=5 nm

175 nm175 nm

In0.53Ga0.47AsT=300 K

• THz Detection: non-linear I-V characteristics Use of NBG materials (Room Temperature ballistic transport) for increased sensitivity and broadband

AC to DC rectification

Frequency (THz)

0.1 1R

ectif

ied

DC

cur

rent

(A/m

)

0.0

0.5

1.0

1.5

2.0

Vo=0.25 V

V=Vosen(2pf)

I

1.4 THz

Enhanced rectification in the THz range

(tunable by geometry)

doc.: IEEE 802.15-15-11-0214-00-0thz

Submission

March 2011


First Experimental ResultsFirst Experimental Results

600nm

Interdigital InGaAs mesa with 2000 etched SSDs

RF power detector up to 110 GHz

0 20 40 60 80 100 120

0.01

0.1

1

10

A

DC

out

put (

mV)

Freq. (GHz)-20 -15 -10 -5 0

0.01

0.1

1

10 B

DC

out

put (

mV)

Power (dBm)

110GHz 50GHz 10GHz 1GHz

doc.: IEEE 802.15-15-11-0214-00-0thz

Submission

March 2011



ROOTHz Project


Slot Diodes

Conclusions


SSDs as THz detectors SSDs as THz emitters

doc.: IEEE 802.15-15-11-0214-00-0thz

Submission

March 2011


SSDsSSDs as THz emitters: Gunn Oscillationsas THz emitters: Gunn Oscillations

Suitable Focused electric field geometry Electron concentration increased by the side field effect

Electric Field (kV/cm)10-1 100 101 102

Elec

tron

velo

city

(105 m

/s)

0.5

1.0

1.5

2.0

2.5

3.0

In0.53Ga0.47As (n.i.d.)

In0.53Ga0.47As (ND=6x1018cm-3)

In0.7Ga0.3As (n.i.d.)

- Pronounced NDM- Low saturation velocity (low frequency)- Low threshold field low power

- InGaAs channels (narrow band gap)

Electric field (kV/cm)

200 400 600 800

Drif

t vel

ocity

(107

cm/s

)

0.0

0.5

1.0

1.5

2.0

2.5

3.0

GaN

GaN channels (wide band gap)

- Less pronounced NDM- High saturation velocity +

Low energy relaxation time- High threshold field high power

high frequency

doc.: IEEE 802.15-15-11-0214-00-0thz

Submission

March 2011


V (V)25 30 35 40 45 50 55 60 65

Freq

uenc

y (G

Hz)

300

350

400

450 (b)

LC=900 nm

WC=75 nm

WV=100 nm

WH=50 nm

500 nm150 nm

GaNT=300 K

Time (ps)

10 15 20 25 30 35 40 45 50

I (m

A)

0.4

0.8

1.2

1.6

2.0(a)

30 V

40 V

50 V

60 V

V (V)

-40 -20 0 20 40 60

I (m

A)

-0.2

0.0

0.2

0.4

0.6

0.8

1.0

Gunn Oscillations

in GaN SSDs

Monte Carlo Simulations

Oscillation frequencies above 400 GHz (voltage controlled and tunable by geometry)

SSDsSSDs as THz emitters: Gunn Oscillationsas THz emitters: Gunn Oscillations

doc.: IEEE 802.15-15-11-0214-00-0thz

Submission

March 2011



16 parallel GaN SSDs

doc.: IEEE 802.15-15-11-0214-00-0thz

Submission

March 2011



‐1.5

‐1.0

‐0.5

0.0

0.5

1.0

1.5

2.0

‐20 ‐15 ‐10 ‐5 0 5 10 15 20Curren

t (mA)

Voltage (V)

1 SSD

4 SSD's

16 SSD's

32 SSD's

RF detection demonstrated even if with small sensitivity (maximum of 50 V/W)

0

10

20

30

40

50

60

220 240 260 280 300 320

Sensitivity (V/W

)

Frequency (GHz)

DC curves: Fabrication of 32 SSDs in parallel validated

Gunn oscillationsnot observed yet

doc.: IEEE 802.15-15-11-0214-00-0thz

Submission

March 2011



ROOTHz Project


Slot Diodes

Conclusions


doc.: IEEE 802.15-15-11-0214-00-0thz

Submission

March 2011


Slot Diodes: Ultra fast Gunn effect for THz generationSlot Diodes: Ultra fast Gunn effect for THz generation

200 nm

15 nm

17 nm

10 nm

LSSource Drain

LR

LD

n.i.d.

n.i.d.

n.i.d.

n.i.d.

ND=6x1018cm-3

=6x1012cm-2

InGaAs

InAlAs

InAlAs

InGaAs

InAlAs

InAlAs

InP

Fast drift of a high field domain along the drain region

Ballistic electrons

Oscillations in the THz range

• Planar geometryand Parallelization

The recess focuses the High Electric

field region

doc.: IEEE 802.15-15-11-0214-00-0thz

Submission

March 2011


Applied voltage (V)0.0 0.2 0.4 0.6 0.8 1.0 1.2

Cur

rent

den

sity

(x10

3 A/m

)

0

1

2

3

4

Time (ps)0 1 2 3

Cur

rent

(x 1

03 A/m

)

0.60.81.01.21.41.61.82.02.2

Time (ps)0 1 2 3

VDS=0.1 V

VDS=0.6 V

VDS=0.8 VVDS=1.0 V

VDS=1.2 V

VDS=0.4 V

VDS (V)0.0 0.2 0.4 0.6 0.8 1.0 1.2 1.4M

ain

Pea

k A

mpl

itude

(10-7

A2 m

-1s)

10-4

10-3

10-2

10-1

100

101

Mai

n P

eak

Freq

uenc

y (T

Hz)

0

1

2

3

4

5

GunnOscillations

PlasmaOscillations

Ultra fast Gunn-like oscillations in the THz range(voltage controlled and tunable by geometry)

Low-amplitude plasma oscillations High-amplitude Gunn-like oscillationsV

V 6.06.0

thDS

thDS

VVVV

Monte Carlo Simulations


doc.: IEEE 802.15-15-11-0214-00-0thz

Submission

March 2011


Intervalley energy level (0.6 eV)

Injection into the upper valleys when there is enough potential

drop in the recess region (and current decreases)

Concentration decrease due to the small velocity of electrons injected into the drain region

(and fast -electrons run away)

High electric field domain created, increase of the potential

drop within the drain region (and injection of -electrons)

Elec

tric

Pot

entia

l(V)

Ele

ctro

nC

once

ntra

tion

(1019

cm-3

) Lon

gitu

dina

l Ele

ctic

Fiel

d(k

V/cm

)

Domain moves at the very fast velocity of -electrons

that refill the depleted region


doc.: IEEE 802.15-15-11-0214-00-0thz

Submission

March 2011


Y D

ata

LR(m -1)0.2 0.3 0.4 0.5 0.6 0.7 0.8

Freq

uenc

y (T

Hz)

0 .5

0.6

0.7

0.8

0.9

1.0


InGaAs - 10nm

=6x1012 cm-2

ND=6x1018 cm-3

InGaAs - 15nm

InAlAs 17nm

InAlAs - 200nm

InP - 200nm

n.i.d.

n.i.d.

n.i.d.

n.i.d.

Source (LS)

Recess (LR)

Drain (LD)

X position

1/LD(m-1)0.0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0

Freq

uenc

y (T

Hz)

0.2

0.4

0.6

0.8

1.0

1.2

1.4

1.6

1.8

2.0

1/LD

Transit time and frequency scale for long LD

Frequency not scaling for short LD due to the increase

of L-valley population

Longer recess lengths decrease the oscillation frequency due to the attenuation of the

“electron-launching effect”

Influence of LD

Influence of LR

doc.: IEEE 802.15-15-11-0214-00-0thz

Submission

March 2011



Strong kink in the I-V curve of all the slot diodes fabricated

0 0.5 1 1.5 2 2.5 30

20

40

60

80

100

120

140

160

180

200

Drain voltage [V]

Dra

in c

urre

nt [

mA

/mm

]

R1A, = 61012 cm-2

W=50 Lr=0.3 Ld=0.55 (μm)

7.6513 [*mm]W=50 Lr=0.5 Ld=0.55 (μm)

9.8717 [*mm]

W=50 Lr=0.9 Ld=0.55 (μm)

15.416 [*mm]

0 0.5 1 1.5 2 2.5 30

20

40

60

80

100

120

140

160

180

200

Drain voltage [V]D

rain

cur

rent

[m

A/m

m]

R2A, = 81012 cm-2

W=50 Lr=0.3 Ld=0.55 (μm)

6.8151 [*mm]W=50 Lr=0.5 Ld=0.55 (μm)

9.9598 [*mm]

W=50 Lr=0.9 Ld=0.55 (μm)

17.3416 [*mm]

doc.: IEEE 802.15-15-11-0214-00-0thz

Submission

March 2011



ROOTHz Project


Slot Diodes

Conclusions


doc.: IEEE 802.15-15-11-0214-00-0thz

Submission

March 2011


Conclusions: Conclusions: ROOTHzROOTHz objectivesobjectives

• THz Detectors: sensitivity above 500 mV/mW in the 0.5-2.0 THz band

• THz Emitters: power exceeding 1mW Narrowband emitters at discrete frequencies of: 1.0, 1.5 and 2.0 THz Broadband emitter in the 0.5-2.0 THz

• Integrated THz detector/emitter prototype: broadband emitter-detector in the range of 0.5-2.0 THz able to obtain the transmission or reflection spectrum of certain benchmark substances

• Room Temperature operation

• Demonstration of Gunn oscillations in GaN SSDs

Exploiting the special geometry and versatility of SSDs and Slot Diodes based on NBG and WBG semiconductors we aim to confirm the results of MC simulations for fabricating and demonstrating:

doc.: IEEE 802.15-15-11-0214-00-0thz

Submission

March 2011


ROOTHzROOTHzSemiconductor Nanodevices for Room Temperature

THz Emission and Detectionwww.roothz.eu

AcknowledgementsAcknowledgements

T. GonzálezD. PardoS. PérezB. G. VasalloH. RodillaI. Íñiguez-de la-TorreA. Íñiguez-de la-Torre

A. M. SongA. RezazadehM. HallsallC. BaloccoL. ZhangY. Alimi

C. GaquiereG. DucournauP. Sangaré

J. GrahnP. A. NilssonA. WestlundH. Zhao

march 2011 doc.: ieee 802.15-15-11-0214-00-0thz … objective and make possible the demonstration of...

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