# Fileset

[SI.pdf](https://mdr.nims.go.jp/filesets/f0000e00-7860-4a23-a2a1-07f456090522/download)

## Creator

[Ibrahima Gueye](https://orcid.org/0000-0001-5296-3894), Akira Yasui, [Yasumasa Takagi](https://orcid.org/0000-0001-8064-3345), Atsushi Ogura, [Osami Sakata](https://orcid.org/0000-0003-2626-0161), [Takahiro Nagata](https://orcid.org/0000-0002-8591-2943)

## Rights

This document is the Accepted Manuscript version of a Published Work that appeared in final form in ACS Applied Materials & Interfaces, copyright © 2025 American Chemical Society after peer review and technical editing by the publisher. To access the final edited and published work see https://doi.org/10.1021/acsami.5c13299.[In Copyright](http://rightsstatements.org/vocab/InC/1.0/)

## Other metadata

[Study of Local Band Bending in <i>n</i>-Channel In<sub>2</sub>O<sub>3</sub> Thin-Film Transistors under Gate and Drain Voltage Stress Using <i>Operando</i> Hard X-ray Photoelectron Spectroscopy](https://mdr.nims.go.jp/datasets/4f6fff5a-b36e-4e97-8744-6b220148856f)

## Fulltext

Supporting InformationStudy of Local Band Bending in n-Channel In2O3 Thin-Film Transistors Under Gate and DrainVoltage Stress Using Operando Hard X-ray Photoelectron SpectroscopyIbrahima Gueye*,1, 2 Akira Yasui,2 Yasumasa Takagi,2 Atsushi Ogura,3, 4 Osami Sakata,2 and Takahiro Nagata*1, 41Research Center for Functional Materials, National Institute for Materials Science (NIMS), 1-1 Namiki, Tsukuba, Ibaraki 305-0044, Japan2Japan Synchrotron Radiation Research Institute, Sayo, Hyogo 679-5198, Japan3Meiji Renewable Energy Laboratory, Meiji University,1-1-1 Higashimita, Tama-ku, Kawasaki, Kanagawa 214-8571, Japan.4Graduate School of Science and Technology, Meiji University,1-1-1 Higashimita, Tama-ku, Kawasaki, Kanagawa 214-8571, Japan.Corresponding Authors: ibrahima.gueye@spring8.or.jp; NAGATA.Takahiro@nims.go.jpThe purpose of this supporting information is to present some additional experimental data relatedto our article on the Study of Local Band Bending and Chemical Change of n-Channel In2O3 Thin-Film Transistor Under Gate and Source Voltage Stress By Using Operando Hard X-ray PhotoelectronSpectroscopy). This work focuses on the chemical change of In2O3 Thin-Film Transistor (TFT)induced by both the gate voltage (VGS) and drain voltage (VDS). Fig. S1 (a-b) shows the opticalimages of our narrow and wide In2O3-TFT, respectively. Using the atomic layer deposition In2O3film as a channel layer, top-contact In2O3-TFTs were fabricated by depositing 5/150 nm thick Ti/Auelectrodes on top of the In2O3-channel layer using electron beam evaporation through a shadowmask, forming the source and drain electrodes. It is observed that the In2O3 channels are wellpositioned between the Source/Drain electrodes. Fig. S2 and Fig. S3 report the current-voltage(I-V) characteristics of the In2O3-TFT recorded during the chemical analysis of the drain (spot II)and source (spot III), respectively, as reported in Figure 2 (b) from the main manuscript. The I-Vdata in Figure 3 were obtained in a static mode (fixed voltage for each step). The (a) label illustratesthe current IDS versus VDS while sweeping VGS at 0 V, 30 V, 100 V, and -20 V, and the (b) labelshows the current IGS versus VGS with VDS set to 0 V and +10 V. This characterization technique isemployed here to investigate the In2O3 film as well as the buried layers and interfaces under differentbias voltage operating conditions.From Table S1, we report the relative area ratio (%) of each In3d component from Figure 5(a) from the main manuscript. We underline that from VDS = 0V /VGS = 0V to VDS = 0V / VGS = 100V, the In0 (Red) increases from 0 % to 4 % at a fixed bindingenergy position (maximum intensity based on Figure 4 (a) from the main manuscript). FromVDS = 0V / VGS = -20V to VDS = 10V / VGS = -20V, we have released the In0 energy position andfixed the maximum intensity (based on Figure 4 (b) from the main manuscript). Finally, at VDS= -0V / VGS = -0V, the In0 comes back to its initial position, and we observe a slight appearanceof peak shoulder as observed in Figure 5 (a) at VDS = -0V / VGS = -0V from the main manuscript.In Fig. S4, we report Si 2s, In 4s, and Al 2s core levels shift and broadening, which are consistentwith the Si 2p3/2, Al 1s, and In 3d data from the main manuscript. From the Si 2s, we observe howthe increase of VGS affects the silicon shape and leads to a huge broadening of the core level. InFig. S5, we show the integrated area as the function of VGS and VDS recorded from the center ofthe TFT. we observed that at VGS = -20V and VDS = 10V, the In 3d highlights a splitting phase dueto the polarization. In Fig. S6, we report additional HAXPES data from a similar In2O3-TFT witha narrow 70 µm length channel. In 3d, Al 1s, Si 2p3/2, and O 1s core levels were obtained aroundthe center of the narrow channel. These data are consistent with the results in Figure 4 in the mainmanuscript, confirming our measurement’s reproducibility. Furthermore, with Fig. S7 and Fig. S8,we respectively present an extended Al 1s and Si 2p3/2 core-level analysis from the 130 µm lengthchannel (complementary data to Figure 7 in the main manuscript) at various X-ray beam positionsand under different VGS (0 V, 30 V, 100 V, and -20 V) and VDS (0 V and +10 V) configurations.This position-dependent investigation (drain side, center, and source side) enables us to evaluatechemical changes along the channels horizontal direction of the L/W (130 µm/ 500 µm) thin filmtransistor. These data were obtained during the measurement of In 3d from Figure 7 in the mainmanuscript. From Fig. S9, a schematic description of the photoelectron transport process throughthe upper stacked layer under applied VDS is presented. By applying a bias along the drain-sourcedirection, we assume a change of the binding energy (BE) of Al 1s and Si 2p3/2 photoelectrons frominitial BE1 to the final BE f = BEi + α(x) VDS when crossing the Al2O3/In2O3 interface. Since In2O3is a semiconductor, we expect that the potential will be constant from the Al2O3/In2O3 interface tothe In2O3 surface. Therefore, no additional binding energy change will occur inside the channel fora constant (x) position (α(x) constant) along the channel length. However, by moving the X-raybeam from the drain side to the source side, we expect a variation of the α(x) and therefore BE f .Due to the modification of the potential (ACS Appl. Mater. Interfaces 2016, 8, 38, 2563125636,10.1021/acsami.6b10332) along the x-axis. Finally, with Fig. S10, we investigate the underneathsource/drain electrodes by using thinner Au/Ti (5nm / 5 nm) stacks. Results point out similar trendsof In 3d. Conversely to the In 3d data from the channel, under the Au/Ti electrodes, we underlinea progressive reduction of the In2O3 underneath the source/drain over the measurement time. Thisresult suggests an impact of the Ti/In2O3 interface on the chemical change of In2O3. We also notethat except for the presence of the In0, no binding energy shift was observed under VGS and VDS.The progressive variation of the In0, In2O3 and In-(OH)x relative area ratio under VDS andVGS is also reported in Fig. S10(c). These quantitative results show that the In0 goes from 10 toaround 30% with the applied bias voltages.S-2Figure S1: Optical microscopy images of the (a) narrow and (b) wide channel of In2O3 thin-film transistors (TFTs) with Au/Tisource and drain electrode.Figure S2: Operando-HAXPES analysis at spot II (drain side of 130 µm length channel TFT): (a) IDS-time curve for differentdrain-source (VDS= 0V and 10V) voltages, (b) IGS-time curve for different drain-source (VGS= 0V, 30V, 100V and -20V)voltages.Figure S3: Operando-HAXPES analysis at spot III (Source side of 130 µm length channel TFT): (a) IDS-time curve for differentdrain-source (VDS= 0V and 10V) voltages, (b) IGS-time curve for different drain-source (VGS= 0V, 30V, 100V and -20V)voltages.S-3Table S1: Quantitative peak fitting of the In 3d core level spectra to distinguish components evolution under varying appliedVDS and VGS bias voltage conditionsBinding energy (eV) as function of the VDS / VGS (Volt / Volt)Components (%) 0 / 0 0 / 30 0 / 100 0 / -20 10 / 0 10 / 30 10 / 100 10 / -20 -0 / -0In0 (Red) 0 1.3 4 4 4 4 4 4 4In2O3 (Blue) 85 83.7 81 81 81 81 81 81 81In-(OH)x (Yellow) 15 15 15 15 15 15 15 15 15Figure S4: HAXPES spectra of Si 2s and In 4s/Al 2s core level from the center of wide 130 µm length channel from theIn2O3/Al2O3/SiO2/p+-Si thin film transistor under varying VGS and VDS.Figure S5: HAXPES spectra of integrated area of In 3d core level from the center of wide 130 µm length channel from theIn2O3/Al2O3/SiO2/p+-Si thin film transistor under varying VGS and VDS.S-4Figure S6: HAXPES spectra of (a)In 3d, (b) Al 1s, (c) Si 2p3/2/Au 4f and (d) O 1s core level from the center of narrow 70 µmlength channel from the In2O3/Al2O3/SiO2/p+-Si thin film transistor under varying VGS and VDS.Figure S7: Al 1s core level shifts under varying VGS and VDS: (a) drain side from spot II, (b) center area from spot I, and (c)source side from spot III (130 µm length channel).S-5Figure S8: Si 2p (Au 4f) core level shifts under varying VGS and VDS: (a) drain side from spot II, (b) center area from spot I,and (c) source side from spot III (130 µm length channel).Figure S9: Schematic potential distribution between the drain and the channel electrode at VDS ̸= 0V and the binding energychange of photoemitted electron from the Al2O3 and SiO2 layers when going through the In2O3 semiconducting layer.S-6Figure S10: Deconvolution of the In 3d and Ti 2p core levels under varying VGS and VDS on the Au(5 nm)/Ti(5 nm) thin (a)drain, (b) source electrodes of the In2O3/Al2O3/SiO2/p+-Si thin film transistor with a 130 µm length channel. (c) Relative ratioof In0, In2O3 and In-(OH)x under varying VGS and VDS.S-7 Study of Local Band Bending in n-Channel In2O3 Thin-Film Transistors Under Gate and Drain Voltage Stress Using Operando Hard X-ray Photoelectron Spectroscopy Abstract