Growth Of Organic Semiconductor Thin Films with Multi-Micron Domain Size and Fabrication of Organic Transistors Using a Stencil Nanosieve

Abstract

To grow small molecule semiconductor thin films with domain size larger than modern-day device sizes, we evaporate the material through a dense array of small apertures, called a stencil nanosieve. The aperture size of 0.5 μm results in low nucleation density, whereas the aperture-to-aperture distance of 0.5 μm provides sufficient crosstalk between neighboring apertures through the diffusion of adsorbed molecules. By integrating the nanosieve in the channel area of a thin-film transistor mask, we show a route for patterning both the organic semiconductor and the metal contacts of thin-film transistors using one mask only and without mask realignment.

Epitaxy of an Organic Semiconductor Templated by Molecular Monolayer Crystals

“…One major reason for the #2 polymorph of C 10 -DNTT to occur is that the value of the c axis is approximately 5 times of the b axis (∼39 to ∼7.8 Å as summarized in Table ), so the bottom thin-film crystal can facilitate both its epitaxy (#1 polymorph) and the growth of the #2 polymorph (lamella). This also explains why the lamellae are the indicator of the bottom-lying grains and why the lamellae on the MMC template are straight and parallel over a much larger area (comparing Figure e,f and Figure b,c) …”

“…This also explains why the lamellae are the indicator of the bottom-lying grains and why the lamellae on the MMC template are straight and parallel over a much larger area (comparing Figure 2e,f and Figure 2b,c). 23 Grazing-incident X-ray diffraction (GI-XRD) experiments are further performed to support the SAED results in determining the crystal structure. In-plane phi scan (sample rotation) results at 2θ χ = 22.4°(corresponding to the (020) d spacing) for the monolayer templates before and after the deposition of 30 nm-thick C 10 -DNTT were compared in Figure 3f.…”

“…We noticed for the C 10 -DNTT thin films grown on either OTS/SiO 2 or the MMC template the long straight lamella structures occurring even from t n = 1 ML. In a previous study, these lamellae are found to be the indicator of the orientation of the bottom-laying grains . However, the exact crystal structure and reason for the lamellae in thin films, which is widely observed in the family of DNTT derivatives, have not yet been studied. − Herein, selected-area electron diffraction (SAED) was utilized to study the regularly aligned lamellae templated by the MMC.…”

Field‐Effect Transistors Based on 2D Organic Semiconductors Developed by a Hybrid Deposition Method

“…These whisker-like lamellas have been reported to be parallel with the direction of a-axis, i.e., [100]. [62] Consequently, we can judge the crystal orientation of each crystal domain using these lamellas as markers. In the case of HTE films, the thermally evaporated compact film with the same lamellas on the surface and almost all the lamellas are parallel to each other within each crystal domain (Figure 4c).…”

“…Each domain contains many tall crystal whiskers that are formed during the thermal deposition with the substrate temperature of 50 °C. These whisker‐like lamellas have been reported to be parallel with the direction of a ‐axis, i.e., [100] . Consequently, we can judge the crystal orientation of each crystal domain using these lamellas as markers.…”