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Supporting Information
On the correlation between gate dielectric, film growth, and charge transport in organic
thin film transistors: the case of vacuum-sublimed tetracene thin films
Julia Wünsche, a
Giuseppe Tarabella, b
Simone Bertolazzi, a
Maimouna Bocoum, a
Nicola Coppedè,
b Luisa Barba,
c Gianmichele Arrighetti,
c Luca Lutterotti,
d Salvatore Iannotta,
b
Fabio Cicoirae and Clara Santato*
a
a Département de génie physique, École Polytechnique de Montréal, CP 6079, Succursale Centre-Ville, Montréal, Québec H3C 3A7 (Canada); Tel: 514 340-4711 # 2586; E-mail: [email protected]
b IMEM-CNR, Parco Area delle Scienze 37/A, 43100 Parma (Italy)
c Institut of Crystallography, CNR, Strada Statale 14, Basovizza, Km 163,5 in AREA Science Park, 34149
Basovizza, Trieste, Italy
d Dipartimento di Ingegneria dei Materiali, Università di Trento Via Mesiano, 77, 38123 Trento (Italy); E-mail:
e Département de génie chimique, École Polytechnique de Montréal, CP 6079, Succursale Centre-Ville,
Montréal, Québec H3C 3A7 (Canada)
Electronic Supplementary Material (ESI) for Journal of Materials Chemistry CThis journal is © The Royal Society of Chemistry 2012
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Figure S1. Surface inclination for 3 µm 3 µm regions of 35 nm thick tetracene films on polystyrene
(PS), parylene C (PARY C), polymethylmethacrylate (PMMA), hexamethyldisilanzane (HMDS) and
untreated SiO2. Please note the different color scales. The plots were obtained by taking the first
derivative of the corresponding Atomic Force Microscopy height images. Tetracene films on HMDS
have the flattest island surface followed by PS, while the surface of tetracene islands is the most
curved on PARY C.
PS PARY C
PMMA HMDS
SiO2
Electronic Supplementary Material (ESI) for Journal of Materials Chemistry CThis journal is © The Royal Society of Chemistry 2012
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Figure S2. Fluorescence Microscopy images of 17 nm thick tetracene films deposited on the different
dielectric layers. The images were obtained on a Zeiss Axio Imager.M1 fluorescence microscope. The
insets show the corresponding Atomic Force Microscopy (AFM) images. While tetracene films on PS,
PARY C, and PMMA have reached full substrate coverage at 17 nm nominal thickness, the black
regions on the fluorescence images for tetracene on HMDS and SiO2 reveal the existence of voids
down to the substrate. We associate the bright spots on the fluorescence images to the higher islands,
visible on the AFM images.
Electronic Supplementary Material (ESI) for Journal of Materials Chemistry CThis journal is © The Royal Society of Chemistry 2012
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PS PARY C
PMMA HMDS
SiO2
Figure S3. Reconstructed pole figures for the (001) crystallographic plane of 50 nm thick tetracene
films deposited on different dielectric layers. The reconstruction is based on the Orientation
Distribution Function calculated in the extended Rietveld refinement. The center of the pole figure
corresponds to the sample normal. Tetracene grains on PS, HMDS, and SiO2 are aligned along the
sample normal. In contrast, most grains on PMMA and PARY C are aligned under a certain angle to
the sample normal. Tetracene films on PMMA and PARY C thus have an inclined texture.
Electronic Supplementary Material (ESI) for Journal of Materials Chemistry CThis journal is © The Royal Society of Chemistry 2012
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PMMA HMDS
Figure S4. Transfer characteristics at saturation for tetracene OTFTs with PMMA and HMDS (VDS = -
60 V). The linear fit of √| | vs VGS is used to extract the hole mobility and the threshold voltage.
OTFT geometry: W = 4 mm and L = 100 µm.
PMMA HMDS
Figure S5. Output characteristics (drain-source current, IDS, versus drain-source voltage, VDS) at
different gate-source voltages, VGS, for tetracene OTFT with PMMA and HMDS. Channel length
L=100 μm and channel width W = 4 mm.
0 -20 -40 -6010-11
10-10
10-9
10-8
10-7
10-6
10-5
10-4
VGS
[V]
0
3x10-3
6x10-3
|I
DS|
[A1/2
]
|I D
S| [A
]
0 -20 -40 -6010-11
10-10
10-9
10-8
10-7
10-6
10-5
10-4
|I
DS|
[A1/2
]
VGS
[V]
|I D
S| [A
]
0
3x10-3
6x10-3
0 -10 -20 -30 -40 -50 -60
0
-2x10-6
-4x10-6
-6x10-6
VGS
= -30 V
ID
S [A
]
VDS
[V]
VGS
= -60 V
VGS
= -45 V
0 -10 -20 -30 -40 -50 -600
-2x10-6
-4x10-6
VGS
= -30 V
ID
S [A
]
VDS
[V]
VGS
= -60 V
VGS
= -45 V
Electronic Supplementary Material (ESI) for Journal of Materials Chemistry CThis journal is © The Royal Society of Chemistry 2012