Contents lists available at ScienceDirect Materials Science in Semiconductor Processing journal homepage: www.elsevier.com/locate/mssp Impact of yttrium concentration on structural characteristics and pH sensing properties of sol-gel derived Y 2 O 3 based electrolyte-insulator-semiconductor sensor Kanishk Singh a , Bih-Show Lou b,c , Jim-Long Her d , Tung-Ming Pan a,e,* a Department of Electronics Engineering, Chang Gung University, Taoyuan, 33302, Taiwan, ROC b Chemistry Division, Center for General Education, Chang Gung University, Taoyuan, 33302, Taiwan, ROC c Department of Nuclear Medicine and Molecular Imaging Center, Chang Gung Memorial Hospital, Taoyuan, 33305, Taiwan, ROC d Division of Natural Science, Center for General Education, Chang Gung University, Taoyuan, 33302, Taiwan, ROC e Division of Urology, Chang Gung Memorial Hospital, Taoyuan, 33305, Taiwan, ROC ARTICLE INFO Keywords: Electrolyte-insulator-semiconductor (EIS) Sol-gel Y 2 O 3 sensing film ABSTRACT The complementary metal-oxide-semiconductor compatible electrolyte-insulator-semiconductor (EIS) platform is a promising tool for the detection of ions and biomolecules. In this investigation, we fabricated a Y 2 O 3 sensing membrane based EIS pH sensor by Pechini sol-gel method. X-ray diffraction, atomic force microscopy and X-ray photoelectron spectroscopy were implemented to analyze the effect of yttrium concentration (0.1, 0.2 and 0.3 M) on the crystalline structure, surface morphology and chemical composition of the sensing membrane, respec- tively. The Y 2 O 3 based EIS sensor fabricated under the 0.2 M concentration manifests the near-super-Nernstian pH response (63.80 mV/pH) and high stability in terms of a low hysteresis voltage (5.7 mV) and a small drift rate (0.18 mV/h). We ascribe that the optimal yttrium content increases the surface roughness of the sensing membrane and the formation of a well-crystallized Y 2 O 3 film as well as a stoichiometric Y 2 O 3 film. 1. Introduction In order to diagnose numerous kinds of ailments, the quantification and minute analysis of biomarker or biomolecules are a significant parameter for biomedical applications [1]. However, the transduction of biological signals in electronic data is a troublesome and challenging task. To overcome these problems, complementary metal-oxide-semi- conductor (CMOS) compatible Si-based sensor integrated with micro- electronic circuits provides an effective dimension for the development of a biosensor platform. In the recent few decades, Si-based devices have been drawn immense attention as a potential tool to quantify an accurate concentration of biomolecules. The Si-based micro-sensor ex- hibited several advantages including, small size and weight, ultra- sensitive, quick measurement capabilities, low cost, high stability, compact instrumentation, and the probability of packaging at wafer level [2,3]. A field-effect transistor (FET) is highly popular and most common semiconductor devices. The fundamental sensing mechanism of FET depends on the alteration of charge carrier distribution on its surface [4,5]. In addition, the intrinsic charge on the biomolecule and diverse biological activities facilitates the change in electrical potential which ultimately affects the sensor characteristics. As the development of FET sensing devices, ion-sensitive field-effect transistor (ISFET) based sensor was originally reported by P. Bergveld in 1970 [6]. It is basically a retrieve version of a metal-oxide-semiconductor field-effect transistor (MOSFET) structure where the metal gate was replaced by a reference electrode and electrolyte solution. After the development of ISFET based sensor, other FET sensing devices, e.g. light-addressable potentiometric sensor (LAPS) [7], extended-gate field-effect transistor (EGFET) [8], silicon nanowire FET (SiNW-FET) [9], and electrolyte- insulator-semiconductor (EIS) [10], gain considerable attention of re- search community. Due to the continuous exposure of source and drain region of ISFET in electrolyte solution results in the degradation of its performance and reliability for long term operations. An EIS based sensor without source and drain electrode provides extra advantages over ISFET which com- prise low cost, ease of fabrication and low drift problem [11]. EIS based sensors have been extensively employed in various kinds of biological applications, for instance, detection of a change in pH from the catalytic reactions from the enzyme, binding of intrinsic charge molecule-like protein and cytochrome, gold nanoparticle, DNA hybridization, and https://doi.org/10.1016/j.mssp.2019.104741 Received 1 July 2019; Received in revised form 11 September 2019; Accepted 13 September 2019 * Corresponding author. Department of Electronics Engineering, Chang Gung University, Taoyuan, 33302, Taiwan, ROC. E-mail address: tmpan@mail.cgu.edu.tw (T.-M. Pan). Materials Science in Semiconductor Processing 105 (2020) 104741 1369-8001/ © 2019 Elsevier Ltd. All rights reserved. T