Printed Electronics: Device Production, Printed Electronics: Device Production, Characterisation and Simulation Characterisation and Simulation D. M . Taylor School of Electronic Engineering Bangor University Dean Street, Bangor, Gwynedd LL57 1UT, UK IeMRC Meeting, Loughborough 19 th March 2012
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Printed Electronics: Device Production, Printed Electronics: Device Production, Characterisation and SimulationCharacterisation and Simulation
D. M . TaylorSchool of Electronic Engineering
Bangor UniversityDean Street, Bangor, Gwynedd LL57 1UT, UK
IeMRC Meeting, Loughborough19th March 2012
1
Roll-to-roll Vacuum-processedCarbon Based Electronics
(RoVaCBE)
DALMATIAN TECHNOLOGY
Outline of PresentationOutline of Presentation
Fabrication/characterisation of vacuum-prepared TFTs
Parameter extraction with Silvaco UTMOST 4
Inverter characteristics
Circuit simulation with Silvaco Gateway
Conclusions
Evaporation zone 5 × 10-4 mbar
Winding zone
Unwind
Selective Metallising
Process Drum
Rewind
Anilox Roller and Oil Boiler Cliché Plate
Magnification x 200
Magnification x 60
Magnification x 200
50 μm lines,
gap 80 μm
REGISTRATION ACCURACY
MD: 500 micron
TD: 500 micron
PRINTING RESOLUTION
MD: 30-50 micron
TD: 30-50 micron
{---
----
Sou
rce/
Dra
in E
lect
rode
s---
---}
250 μmSource/DrainW/L = 16
0.4 μm diacrylate
Gate
90 nm pentacene
75 μm PET substrate
Diacrylate monomer
E-beam cure
Pentacene
Abbas et al (2011) J.Vac.Sci.Technol.B, 29, 052401
RR--22--R Vacuum Deposition ProcessR Vacuum Deposition Process
250 μmSource/DrainW/L = 16
0.4 μm diacrylate
Gate
90 nm pentacene
75 μm PET substrate
Diacrylate monomer
E-beam cure
Pentacene
Abbas et al (2011) J.Vac.Sci.Technol.B, 29, 052401
μ=0.09 cm2/VsVT = 10VOn/Off ratio ~ 103
RR--22--R Vacuum Deposition ProcessR Vacuum Deposition Process
Pentacene TFTs on PENPentacene TFTs on PEN
-5.E-06
-4.E-06
-3.E-06
-2.E-06
-1.E-06
0.E+00
1.E-06
-50 -40 -30 -20 -10 0 10
VD (V)
I D (A
)
Vg=-10VVg=-20VVg=-30VVg=-40VVg=-50V
-12
-11
-10
-9
-8
-7
-6
-5
-50 -40 -30 -20 -10 0 10 20
VG (V)
Log 1
0(ID/A
)
I (Vd=-10V)I (Vd=-20V)I (Vd=-30V)
Good saturation, no hysteresis, on/off ratio ~105
0.0E+00
5.0E-04
1.0E-03
1.5E-03
2.0E-03
-50 -40 -30 -20 -10 0 10 20VG (V)
ID0.
5 (A)0.
5
Vd=-10VVd=-20VVd=-30V
0.00
0.01
0.02
0.03
0.04
0.05
-50 -40 -30 -20 -10 0 10 20
VG (V)
Mob
ility
(cm2 /V
s)
VT = -17V to -21V
Pentacene TFTs on PENPentacene TFTs on PEN
Mobility extracted from
⎟⎠⎞
⎜⎝⎛= i
GC
LW
dVId μ
2
Test StructureTest Structure
DNTT Devices on HMDSDNTT Devices on HMDS--treated Si/SiOtreated Si/SiO22S
S
Dinaphthothieno thiophene
DNTT Devices on HMDSDNTT Devices on HMDS--treated Si/SiOtreated Si/SiO22
Device Modelling with UTMOST 4Device Modelling with UTMOST 4Parameter Extraction
Universal Organic TFT Model (Level=37)
The UOTFT model:An extension of unified charge control model previously used for a-Si and poly-Si TFTs.
Based on:Operation in accumulation mode in the presence of an exponential density of states and interface trapsUnified expression for gate induced charge in the conductive channelUnified charge-based description of mobility and drain-source currentA universal power mobility law valid in all operation regions
Device Modelling with UTMOST 4Device Modelling with UTMOST 4Parameter Extraction
Unified Charge Description of Mobility
( )864.150
4839.841 2 +−=
xxk
O
Tgs
VVV
u−
=
( )( ) ( )⎥⎥⎦
⎤
⎢⎢⎣
⎡
++++⋅=⋅=− +
+
1
1
0 1ln211ln u
u
Oigseiacc eukeVCVCQ
( ) γ
μμ ⎟⎟⎠
⎞⎜⎜⎝
⎛⋅
−⋅=
ACCi
accACC VC
Q 0
μACC characteristic effective mobility in channelVACC characteristic voltage of the effective mobilityVO characteristic voltage of the trap density of
statesVT zero bias threshold voltageγ power law mobility parameter
VG
VDIDMISFET
+ + + + + + +
Device Modelling with UTMOST 4Device Modelling with UTMOST 4Optimisation Routine
Set: TINS, εINS, εS
Extract: VO, VT, μACC and γ from ID-VG plots at low VD
Extract: RS, ASAT and λ from ID-VG plots at high VD
Extract: MSAT,RD from ID-VD plots
Iterate to obtain best fit using different optimisation procedures
Genetic
Marquand-Levenberg
Simulated Annealing
SimulationsEvaporated pentacene bottom-gate TFT on acrylate dielectric