Supplementary data for

Downsizing gas sensors based on semiconducting metal oxide: Effects of

electrodes on gas sensing properties

Young Geun Songa,b,†, Young-Seok Shima,†, Sangtae Kima, Soo Deok Hana,c, Hi Gyu Moona,

Myoung Sub Noha,c, Kwangjae Leed, Hae Ryong Leee, Jin-Sang Kima, Byeong-Kwon Jub, and

Chong-Yun Kanga,c,*

a Center for Electronic Materials, Korea Institute of Science and Technology (KIST), Seoul,

02791, Republic of Koreab Display and Nanosystem Laboratory, College of Engineering, Korea University, Seoul,

02841, Republic of Koreac KU-KIST Graduate School of Converging Science and Technology, Korea University, Seoul,

02841, Republic of Korea d Contents Convergence Research Center, Korea Electronics Technology Institute (KETI),

Seoul, 03924, Republic of Koreae Smart Game Platform Research Section, SW•Content Research Laboratory, Electronics and

Telecommunications Research Institute, Daejeon, 34129, Republic of Korea

† These authors contributed equally.

*Corresponding author. Tel.: +82 2 958 6722; fax: +82 2 958 6720.

L

W

D

Figure S1. Simplified schematics of interdigitated electrodes (IDEs) for calculating the

resistance. Rt total resistance of In2O3 layer is calculated with the number of active area (n),

resistivity (ρ), width (W ), length (L), and depth (D) between electrodes.

Table S1. Characterization of commercialized metal oxide gas sensor properties.

Table S2. Base resistance of In2O3 thin film and nanocolumns at working temperature of

300ºC as a function of IDE size and tile angle.

Base resistance Thin film ( ) 78o nanocolumns ( ) 82o nanocolumns ( ) 85o nanocolumns ( )Commercial sensors 103 – 106

1 mm x 1 mm 3.64 x 101 2.02 x 102 3.34 x 102 5.84 x 104

0.5 mm X 0.5 mm 9.13 x 101 2.98 x 102 9.96 x 103 3.11 x 105

0.3 mm X 0.3 mm 3.34 x 102 1.40 x 103 1.55 x 104 1.06 x 106

0.1 mm X 0.1 mm 8.03 x 102 2.42 x 105 2.37 x 104 2.83 x 107

Table S3. Sensing resistance of In2O3 thin film and nanocolumns to 50 ppm C2H5OH at

working temperature of 300ºC as a function of IDE size and tile angle.

Sensing resistance Thin film ( ) 78o nanocolumns ( ) 82o nanocolumns ( ) 85o nanocolumns ( )

Commercial sensors 102 – 104

1 mm x 1 mm 32.15 29.74 78.24 71.03

0.5 mm X 0.5 mm 47.72 43.69 1.74 x 102 2.85 x 102

0.3 mm X 0.3 mm 72 80 3.26 x 102 8.67 x 102

0.1 mm X 0.1 mm 1.29 x 102 8.65 x 102 5.36 x 103 1.41 x 104

Table S4. Response of In2O3 thin film and nanocolumns to 50 ppm C2H5OH at working

temperature of 300ºC as a function of IDE size and tile angle.

Response ( ) Thin film 78o nanocolumns 82o nanocolumns 85o nanocolumns

Commercial sensors 102 – 104

1 mm x 1 mm 1.13 7.1 4.59 877

0.5 mm X 0.5 mm 1.49 7.06 60.71 1174

0.3 mm X 0.3 mm 4.63 17.91 49.7 13010.1 mm X 0.1 mm 6.22 27.95 46.12 2066