Supporting Information Fabrication of High-Performance Ultrathin In 2 O 3 Film Field-Effect Transistors and Biosensors Using Chemical Lift-Off Lithography Jaemyung Kim,,,# You Seung Rim,,,# Huajun Chen,, Huan H. Cao,, Nako Nakatsuka,, Hannah L. Hinton,, Chuanzhen Zhao,,, Anne M. Andrews,*,,,± Yang Yang,*,, and Paul S. Weiss*,,, California NanoSystems Institute, University of California, Los Angeles, Los Angeles, California 90095, United States Department of Chemistry and Biochemistry, University of California, Los Angeles, Los Angeles, California 90095, United States Department of Materials Science and Engineering, University of California, Los Angeles, Los Angeles, California 90095, United States Department of Materials Science and Engineering, Beijing Institute of Technology, Beijing, China 100081 ± Department of Psychiatry and Semel Institute for Neuroscience and Human Behavior, University of California, Los Angeles, Los Angeles, California 90095, United States *To whom correspondence should be addressed: aandrews@mednet.ucla.edu (A. M. A.); yangy@ucla.edu (Y. Y.); psw@cnsi.ucla.edu (P. S. W.)
Figure S1. Field-effect transistor device patterns on a SiO2/Si substrate produced by chemical lift-off lithography with a short processing time (5 min self-assembled monolayer deposition, 5 min stamping process). Figure S2. Scanning electron microscope images of channel regions. (a) A representative source-drain electrode pair used for device fabrication. (b) A transmission line measurement (TLM) pattern with varying channel lengths. S1
Figure S3. Bottom-gate bottom-contact field-effect transistor transfer characteristics of ultrathin In 2 O 3 layers annealed at (a) 200 C, (b) 250 C, and (c) 300 C for 1 h. Coating Method Channel Thickness (nm) µ sat (cm 2 V -1 s -1 ) I ON /I OFF SS (V dec -1 ) Sol gel 4 12 10 7 1.6 Our work Sol gel 30 0.7 10 6 5.7 S1 Sol gel 25 2.24 10 8 0.45 S2 Sol gel 6 7.5 10 7 N/A S3 Sol gel 30 3.37 10 7 N/A S4 Sputtering 8 15.3 10 8 0.25 S5 Sputtering 10 15 10 6 N/A S6 Ref. Table S1. Device performance of previously reported In 2 O 3 field-effect transistors. S2
Figure S4. Bottom-gate top-contact field-effect transistor (a) transfer and (b) output characteristics of ultrathin In 2 O 3 layers. Geometry Annealing Temperature ( C) µ sat (cm 2 V -1 s -1 ) I ON /I OFF SS (V dec -1 ) V th (V) a BGBC 200 2.3 ± 0.2 ~10 6 1.2 ± 0.1 19.5 ± 2.1 BGBC 250 11.5 ± 1.3 ~10 7 1.6 ± 0.1 15.6 ± 2.0 BGBC 300 10.4 ± 1.8 ~10 7 2.7 ± 0.9 18.2 ± 1.2 BGTC 250 12.1 ± 3.5 ~10 8 0.9 ± 0.2 9.5 ± 2.7 a Threshold voltage Table S2. Summary of In 2 O 3 field-effect transistor device performance. S3
Figure S5. Scanning electron microscope images of submicrometer-channel devices with gap lengths measuring (b) 300 nm and (c) 150 nm. S4
Figure S6. Cyclic voltammogram of a Pt wire in 0.1 PBS with (red: C DA = 1 mm, green: C DA = 1 µm) or without (blue) dopamine. S5
Figure S7. Transfer characteristics of devices with (green) or without (blue) the In 2 O 3 channel layer, confirming that the leakage current through a liquid electrolyte (blue) is negligible. S6
Figure S8. Transfer characteristics of In 2 O 3 field-effect transistors without aptamer immobilization. For C DA 1 µm, non-specific binding of dopamine on the channel surface becomes significant and causes upward shift in the drain current even without aptamer functionalization. No significant change in drain current was observed for C DA <1 µm. S7
Figure S9. Transfer characteristics of In 2 O 3 field-effect transistors constructed using (a) an aptamer with mutations at the binding sites or (b) a DNA with a random base sequence. In both cases, the addition of 10 nm dopamine to 0.1 PBS induced only small changes in drain currents. (c) ΔV cal of both devices were measured to be less than 15% of the responses from devices constructed using the correct dopamine (DA) aptamer. References (S1) Kim, H. S.; Byrne, P. D.; Facchetti, A.; Marks, T. J. High Performance Solution-Processed Indium Oxide Thin-Film Transistors. J. Am. Chem. Soc. 2008, 130, 12580-12581. (S2) Rim, Y. S.; Lim, H. S.; Kim, H. J. Low-Temperature Metal-Oxide Thin-Film Transistors Formed by Directly Photopatternable and Combustible Solution Synthesis. ACS Appl. Mater. Inter. 2013, 5, 3565-3571. (S3) Choi, C.-H.; Han, S.-Y.; Su, Y.-W.; Fang, Z.; Lin, L.-Y.; Cheng, C.-C.; Chang, C.-H. Fabrication of High-Performance, Low-Temperature Solution Processed Amorphous Indium Oxide Thin-Film Transistors Using a Volatile Nitrate Precursor. J. Mater. Chem. C 2015, 3, 854-860. (S4) Kim, M.-G.; Kanatzidis, M. G.; Facchetti, A.; Marks, T. J. Low-Temperature Fabrication of High-Performance Metal Oxide Thin-Film Electronics via Combustion Processing. Nat. Mater. 2011, 10, 382-388. (S5) Joo Hyon, N.; Seung Yoon, R.; Sung Jin, J.; Chang Su, K.; Sung-Woo, S.; Rack, P. D.; Dong-Joo, K.; Hong Koo, B. Indium Oxide Thin-Film Transistors Fabricated by RF Sputtering at Room Temperature. IEEE Electron Device Lett. 2010, 31, 567-569. (S6) Jiao, Y.; Zhang, X.; Zhai, J.; Yu, X.; Ding, L.; Zhang, W. Bottom-Gate Amorphous In 2 O 3 Thin Film Transistors Fabricated by Magnetron Sputtering. Electron. Mater. Lett. 2013, 9, 279-282. S8