Received 21 November 2020; accepted 29 December 2020. Date of publication 1 January 2021; date of current version 28 January 2021. The review of this article was arranged by Editor C. Surya. Digital Object Identifier 10.1109/JEDS.2020.3048725 Exceptionally Linear and Highly Sensitive Photo-Induced Unipolar Inverter Device MUHAMMAD NAQI 1 , JI YE LEE 2 , BYEONG HYEON LEE 3,4 , SUNKOOK KIM 1 , SANG YEOL LEE 5 , AND HOCHEON YOO 5 1 Department of Advanced Materials Science and Engineering, Sungkyunkwan University, Suwon 16419, South Korea 2 Department of Semiconductor Engineering, Cheongju University, Cheongju 28503, South Korea 3 Korea University, Seoul 136-701, South Korea 4 Research Institute of Advanced Semiconductor Convergence Technology, Chongju 28503, North Korea 5 Department of Electronic Engineering, Gachon University, Seongnam 13120, South Korea CORRESPONDING AUTHORS: S. Y. LEE AND H. YOO. (e-mail: sylee2020@gachon.ac.kr; hyoo@gachon.ac.kr) This work was supported in part by the National Research Foundation of Korea under Grant NRF-2018R1A2B2003558; in part by the Basic Science Research Program through the National Research Foundation of Korea (NRF) funded by the Ministry of Education under Grant NRF 2017R1D1A3B06033837; in part by the Korea Institute of Energy Technology Evaluation and Planning (KETEP); in part by the Ministry of Trade, Industry and Energy (MOTIE) of the Republic of Korea under Grant 20172010104940; and in part by the MSIT (Ministry of Science and ICT), Korea, under the Grand Information Technology Research Center Support Program under Grant IITP-2020-0-01462 supervised by the IITP (Institute for Information & Communications Technology Planning & Evaluation). The work of Hocheon Yoo was supported by the National Research Foundation of Korea Grant funded by the Korea Government (MSIT) under Grant NRF-2020M3A9E4104385 and Grant NRF-2020R1A2C1101647. (Muhammad Naqi and Ji Ye Lee contributed equally to this work.) ABSTRACT Oxide semiconductors are of particular interest in the field of integrated electronics due to their large-area fabrication, high uniformity, and superior performance. Here, we report an exceptionally sensitive photo-induced inverter device with high linearity based on the unipolar n-type channel material amorphous silicon indium zinc oxide (a-SIZO). The field-effect transistor (FET) based on a-SIZO exhibits maximum mobility of 9.8 cm 2 /Vs at V D of 5 V, high on/off ratio of ∼ 10 6 , and stable threshold voltage (V Th ) of -0.35 V. Additionally, the optical properties of the proposed FET include excellent V Th shift and photocurrent (I photo ) with high linearity under various red-light illumination. The proposed enhancement- load type inverter device shows reliable electrical and optical characteristics with an inverter gain of 0.7 at V DD of 1 V and linear photo-response in terms of inverter gain and voltage shift, demonstrating promising potential in the field of integrated electronics for optoelectronic applications. INDEX TERMS Unipolar inverter, amorphous silicon indium zinc oxide (a-SIZO), field-effect transis- tor (FET), phototransistor, photo-induced inverter. I. INTRODUCTION Oxide semiconductors have gained tremendous attention in the field of integrated electronics due to their high- electrical performance, large-area fabrication, and simple processing techniques [1], [2]. Recently, the use of vari- ous organic and oxide semiconductor material systems for p- and n-type material in high-electrical performance com- plementary metal-oxide-semiconductor devices have been reported but limited by the complex structure and costly and complicated processing techniques [3], [4]. To over- come this issue, unipolar integrated circuits (ICs) have been reported to achieve greater electrical performance and high integration using only n- or p-type semiconductor material, having relatively simple structure and pro- cessing methods [5], [6]. Previously, oxide semiconduc- tor material systems gained much attention in the elec- tronic and optoelectronic field due to their wide bandgap (>3.2 eV) and superior carrier transport properties despite their amorphous structure and low-temperature process- ing requirements [2], [7]–[9]. Among the various types of photo-sensitive devices, amorphous oxide semiconduc- tors (AOSs) are exceptionally promising channel materials due to their visible spectral wavelength detectivity and intensity-selectivity of incident light [9], [10]. Despite their integration in high-performance FET devices, much effort is still required to investigate the properties of AOS-based This work is licensed under a Creative Commons Attribution 4.0 License. For more information, see https://creativecommons.org/licenses/by/4.0/ 180 VOLUME 9, 2021