Zinc and
Tin oxide
precursors
Solvents
and
Additives
Source; Drain
and Gate
Development
of the
printable ink
Daniela Salgueiro
PhD. Student
Ink
Rheology
Ink-jet printing process
Inkjet printed
ZTO
semiconductor
Substrate
Supervisor: Prof. Elvira Fortunato
Co–Supervisor: Prof. Pedro
Barquinha
Objectives
 Development of indium free amorphous metal oxide semiconductors produced by solutionprocessed techniques (ZTO-based semiconductors).
Auto-Combustion Reaction
 Deposition by Spin-coating, Spray-Coating and Inkjet printing techniques.
 Production of high-performance TFTs with (post-)processing temperature compatible with flexible
and low cost substrates such as polymers or paper.
 Demonstrate circuit integration capability by fabrication of a flexible n-type inverter circuit using
ZTO-based TFTs produced by ink-jet.
Methods and techniques
1.Materials synthesis and formulations. Solutions characterization
•Choice of adequate ZTO precursors, adequate solvents and other additives considering the
deposition technique
Deposition techniques
•Characterization of ZTO solution (DSC-TG and Rheology)
2.Deposition and characterization of thin films
•Tuning of deposition parameters for spin- and spray-coating and inkjet printing
•Thin film characterization (SEM, EDS, AFM, XRD, FTIR, PL, TEM, XPS)
3.TFTs and inverters fabrication and characterization
•Shadow masks, optical lithography, simultaneous deposition and patterning (inkjet)
•Static and dynamic electrical measurements, bias and illumination stress
Results
Obtained Results
• Si/SiO2 and Glass/ITO/ATO substrates were used to deposited ZTO by spin-coating with similar
performance as a thin film transistor.
• Reduction of the gate current by optimization of the semiconductor patterning.
Electrical Characterization of TFT
• Deposition of ZTO-based amorphous semiconductors at low temperature (T<300 °C) with good
10-3
uniformity and reproducibility up to 2.5x2.5 cm substrate areas and good stability over time.
10-4
10-5
ZTO – WP (without pattern)
W/L = 1400/100
VDS=15V
µFE=2 cm2VS-1
On/Off=106
10-6
Expected Results
• Solution-processed ZTO-based TFTs with µ>10 cm2/Vs and ∆VT<2 V under negative bias illumination
stress.
ID _WP
IG _WP
ID _P
IG _P
-7
I D (A)
10
10-8
10-9
SiO2
Al
Si
10-10
ZTO – P (patterned)
10-11
10-12
-5
0
5
10
15
SiO2
20
VG (V)
Si
• N-type inverters operating above 10 kHz based on transparent ZTO TFTs produced by inkjet printing
on flexible substrates.
Publications
10-3
ZTO – WP
Cycloadditions of Erythrose Benzylidene-acetal 1,3-Butadienes with Maleimides", Synlett, 2012, 23,
1765-1768.
 Salgueiro, D., Alves, M.J., Sousa C., Gil Fortes, A., “Diels-Alder Cycloaddition in the Synthesis of 1Azafagomine, Analogues, and Derivatives as Glycosidase Inhibitors”, Mini Reviews in Medicinal
Chemistry, 2012, 12 (14), 1465-1476.
10-5
Al
W/L = 1400/100
VDS=15V
µFE=2 cm2VS-1
On/Off=106
10-6
ATO
ITO
Glass
 Salgueiro, D., Duarte, V., Sousa, C., Alves, M.J., Gil Fortes, A., "Diastereoselectivity in Diels–Alder
10-4
I D (A)
CENIMAT – Materials Research Centre, New
University of Lisbon
Ink-jet printing of amorphous oxide
semiconductors for high performance TFTs
10-7
10-8
10-9
10-10
ID _WP
IG _WP
10-11
10-12
-5
0
5
10
VG (V)
15
20