HIGH PERFORMANCE SiC-FET GAS SENSORS FOR HIGHLY … · 2016. 10. 16. · Ir-gate SiC-FET 330 °C < 0.5 Pt-gate Ir-gate Detection limits under threshold of legal requirements 7 Faster

ESF provides the COST Office

through a European Commission contractCOST is supported

by the EU Framework Programme

European Network on New Sensing Technologies for Air Pollution Control

and Environmental Sustainability - EuNetAir

COST Action TD1105

Final Meeting at PRAGUE (CZ), 5-7 October 2016

New Sensing Technologies for Air Quality Monitoring

Action Start date: 01/07/2012 - Action End date: 15/05/2016 - EXTENSION: 15/11/2016

HIGH PERFORMANCE SiC-FET GAS SENSORS FOR

HIGHLY SENSITIVE DETECTION OF HAZARDOUS

INDOOR AIR POLLUTANTS

Donatella Puglisi

Participant

Linköping University / Sweden

[email protected]

2

Scientific context and objectives in the Action

• Background / Problem statement

Indoor air is 2x... 5x (even 100x) more polluted than outdoor air (EPA).

Adverse effects on health, environment, economy.

Inadequate ventilation

as a primary cause of

indoor air pollution.

Why Indoor Air Pollution is such an important issue?

• Brief reminder of MoU objectives:

• WG1: Development of gas-sensitive nanomaterials for detection of

specific air pollutants, and integration in gas sensor devices for indoor AQC

• WG2: Design, fabrication, testing, characterization of low-cost, high-

performance gas sensors using innovative SiC-FET sensor technology

3

Current research activities at Linköping University

• Current research topics / Problem statement:

• Highly sensitive, selective, low-cost gas sensors for indoor/outdoor AQC

applications (NOx, NH3, SO2, methane, VOCs,…), e.g.:

• Combustion control in car exhausts

• Monitoring ammonia slip in selective catalytic reduction (SCR)

systems of diesel trucks

• Sulfur dioxide monitoring in power plants

• Particle detectors

• Within SENSIndoor:

• Development of high performance SiC-FETs (LiU, SenSiC)

• Characterization of optimized sensing layers (LiU, U. Oulu, Picodeon)

• Smart operation and advanced data evaluation (USAAR)

• Field tests (ongoing)

4

SiC-FET – Transducer platform

Innovation SiC-FET: • Detection limits under threshold of legal requirements • Discrimination and quantification of specific VOCs • Stability during long-term operation

2 mm × 2 mm

Adapted from C. Bur,

Doctoral Thesis (2015)

Source of the

charge carriers

Metal contact, crucial to make a

MISFET gas sensitive

The current ID flows

from drain to source

Highly favorable for gas

sensing applications

5

Fabrication of the sensing layer

Pulsed Laser Deposition (PLD)

WO3, (V2O5)

DC Magnetron Sputtering

Ir, Pt

Reproducibility of chemical composition

Control of crystal

structure, stochiometry

• Pure metal

(Ir, Pt)

• Pure metal oxide

(WO3, V2O5)

• Metal/Metal oxide

(Ir/WO3, Pt/WO3)

0 5 10 15 20 25 30 35 40 45 50 55 60

235

240

245

250

255

260

265

270

275

12.525

50100150

200

200150

10050

2512.5

Ir-gated SiC-FET @ 300 °C

Sensor

Sig

nal, I

D (

A)

Time (h)

Formaldehyde (ppb)

Sensor Signal

6

Current at a

constant voltage

Repeatability and

low ppb detection

Operating temperature

High sensor

response

10 30 40 600.00

0.05

0.10

0.15

0.20

0.25 Naphthalene

Formaldehyde

Benzene

Rela

tive

Re

spo

nse (

%)

Relative Humidity (%)

< 0.5

10 30 40 600

2

4

6

8

10

Dete

ctio

n L

imit (

pp

b)

Pt-gate SiC-FET

0 10 20 30 40 50 60

0

1

2

3

4

5

6

7

8

9

10

Det

ectio

n Li

mit

(ppb

)

Relative Humidity (%)

Formaldehyde

Benzene

Naphthalene

Ir-gate SiC-FET

330 °C

< 0.5

Pt-gate Ir-gate Detection limits under

threshold of legal

requirements

7

Faster response time Higher relative response

Detection limits under

threshold of legal

requirements

Challenge addressed: extremely high sensitivity

dry air 10 20 30 40 60 20+EtOH

0

5

10

15

20

25

30

Rel

ativ

e R

espo

nse

(%)

Relative Humidity (%)

10 ppb

5 ppb

1 ppb

0.5 ppb

Ir-gate SiC-FET

Naphthalene

Morphology Surface potential

Height (nm) 60 nm ΔVpot (mV) 200 mV

10 µm

Insulator Gate Insulator Gate

ΔVpot (mV) 30 mV Height (nm) 30 nm

3 μm × 3 µm

Pt-gate Ir-gate

Degradation of sensing

layer

No degradation of sensing

layer

≈ 25 mV

Delamination

ΔVpot (mV) 30

mV

3 μm × 3 µm

Height (nm) 50

nm

≈ 10 mV Nanoparticle formation

J. Eriksson (2014)

8

Challenge addressed: long-term operation

Ir-gate SiC-FET: extremely high sensitivity

and robustness!

9

WO3: porous or thin film? PLD depositions at Univ. Oulu

• Porous as-deposited WO3 layers by

PLD at RT and (a) p(O2) = 0.2 mbar or

(b) 0.08 mbar (SEM images).

(a) (b)

(a) (b)

The gate contact is processed by sputter deposition of porous Ir on top of WO3 (Ir/WO3).

The gate contact is pure WO3.

• Dense WO3 thin films deposited in-situ by PLD at 450 °C and (a) p(O2) = 0.02 mbar or (b) 0.05 mbar (AFM images).

• Poor sensitivity and lack of selectivity due to

• Wide band gap, high resistivity, low reactivity of the MOX

• Short life time, lack of stability

• Addition of a noble metal to enhance sensitivity and selectivity

• Ir is among the most effective catalysts for sensing reducing

gases (e.g. HC)

10

Temperature dependence

6 8 10 12 14 16359

360

361

362

363

364

Sensor

Sig

nal, I

D (

A)

Time (h)

Linear region

VDS

= 1.0 V

201

202

203

204

205

206

1010

50

100Saturation regionV

DS = 4.0 V

Ir/WO3 SiC-FET

300 °C

C6H

6 (ppb)

100

5010

0 1 2 3 4 50

100

200

300

400

500

600

700

400°C

350°C300°C

250°C

200°C

150°C

Dra

in C

urr

en

t (

A)

Drain-Source Voltage (V)

Ir/WO3-gated

SiC-FET Oper. point

Sat. reg.

Effect of the electrical

operating point

Electrical characterization

0 50 100 150 200 2500.0

0.5

1.0

1.5

2.0

2.5

225 °C

300 °C

S

enso

r R

esp

on

se

, I D

(

A)

Concentration of Benzene (ppb)

Ir/WO3 SiC-FET

Linear region

Onset of saturation

300 °C

225 °C

Gas tests

10 50 1000.0

0.5

1.0

1.5

2.0

2.5

Ir/WO3 SiC-FET

300 °C

Sensor

Respo

nse, I D

(

A)

Concentration of Benzene (ppb)

Linear region

Onset of saturation region

Saturation region

D. Puglisi et al., Mat. Sci. Forum 858 (2016) 997-1000.

11

Sensitivity Ir vs Ir/WO3 SiC-FETs

10 1000

1

2

3

4

5

6

7

8

SiC-FET

300 °C

R

ela

tive R

esponse (

%)

Formaldehyde (ppb)

Ir

Ir/WO3

10 100

Benzene (ppb)

Ir

Ir/WO3

SiC-FET

300 °C

D. Puglisi et al., Conf. Proc. Indoor Air 2016.

12

Discrimination of naphthalene independent of ethanol’s presence

M. Bastuck et al., Thin Solid Films (2016), in press.

Challenge addressed: Enhanced selectivity

to naphthalene with Ir/WO3

0 10 20 30 40 50 60 700

2

4

6

eth

anol (p

pm

)

0 10 20 30 40 50 60 70

time (h)

0

10

20

30

40

naphth

ale

ne (

ppb)

Gas exposure profile

13

Field test setup Montessoriskolan Trilobiten, Linköping

Jun. – Sept. 2016

~80 cm

FET 3S electronics

FM-801

CH2O monitor

Mini-PC/

Computer stick

4G modem

NI-DAQ 6215

SenseAir CO2 Temp.

Hum.

14

Screenshot of the field test running

VDS = 4V

ID

Temp. cycles

15

Research Facilities available for current research

• Clean room, ISO 6 (magnetron sputtering, lithography, CVD, etc.)

• Sensor processing and characterization (gas mixing systems,

readout electronics, bonding machine, spot welding, scribers,

thermal evaporation, shadow masks, optical microscopes, AFM,

SEM, etc.)

• Hardware and software for data acquisition and data analysis

• Gas bottles: CH2O, C6H6, CO, NO, NO2, NH3, N2, O2, synthetic air

• Other facilities available at: Saarland University, SenSiC,

University of Oulu, Picodeon, 3S

16

Suggested R&I Needs for future research

Research direction

• Field tests: evaluation and testing

• Networking / complementary cooperation

• Dissemination of results / press release within and outside Europe, web

R&I Needs

• Creation of a sustainable environment for the future generations and ourselves: healthy, comfortable, energy-efficient

• Development of low cost, user-friendly sensors/sensor systems for detection of specific hazardous VOCs (formaldehyde is hot topic) – today CO2, TVOC

Innovation SiC-FET

• Versatile technology – operation over a wide temperature range

• Extremely high sensitivity – detection limits under threshold of current legal requirements

• Enhanced selectivity through optimization of the sensing layer and dynamic operation (TCO) – discrimination and quantification (formaldehyde, benzene, naphthalene)

Benefits

• Our SiC-FET sensor will work as a switcher: for on demand ventilation, «below threshold» means ventilation not needed – low cost, energy-efficient, user-friendly

Acknowledgements

17

Thank you for your attention! incl. STSM at USAAR (2013)