Contents lists available at ScienceDirect Ceramics International journal homepage: www.elsevier.com/locate/ceramint Formation of high ultraviolet transparent SrVOx/Ag-based conducting electrode Su-Kyung Kim a , Jin-Woo Cho b , Hyeong-Seop Im a , Weon-Cheol Lim c , Sun-Kyung Kim b , Tae-Yeon Seong a,* a Department of Materials Science and Engineering, Korea University, Seoul, 02841, Republic of Korea b Department of Applied Physics, Kyung Hee University, Gyeonggi-do, 17104, Republic of Korea c Advanced Analysis Center, Korea Institute of Science and Technology, Seoul, 02792, Republic of Korea ARTICLE INFO Keywords: SrVO x Ag layer Transparent conducting electrode Ultraviolet transparency Oxide/metal/oxide multilayer Phasor analysis ABSTRACT Sputter-deposited SrVO x was employed to create transparent conducting SrVO x /Ag/SrVO x films and their op- tical-electrical properties were examined as functions of SrVO x and Ag thicknesses. With the increase in the thickness of SrVO x films from 15 to 45 nm in the SrVO x /Ag/SrVO x films, the carrier concentration, sheet re- sistance, and electron mobility were in the range of 2.0 × 10 22 - 1.03 × 10 22 cm -3 , 3.15-2.76 Ω/sq., and 21.99-19.76 cm 2 /Vs, respectively. The 25 nm-thick SrVO x -based multilayer gave the highest average trans- mittance (T av ) of 91.5%. The 25 nm-thick SrVO x -based multilayer gave the largest Haacke's figure of merit (FOM) of 144.5 × 10 -3 Ω -1 . With increasing Ag layer thickness from 9 to 21 nm, the carrier concentration, mobility and sheet resistance of the multilayers were in the range of 1.05 × 10 22 - 1.99 × 10 22 cm -3 , 15.56-22.46 cm 2 /Vs, and 1.97-6.48 Ω/sq., respectively. The T av of the SrVO x (25 nm)/Ag/SrVO x (25 nm) multilayer gradually decreased from 95.5 to 82.6% with the Ag layer thickness. The rigorous coupled-wave (RCW) simulations were performed to describe the wavelength-dependent transmittance characteristics of the SrVO x (25 nm)/Ag (15 nm)/SrVO x (25 nm) samples. Based on the phasor examination, the effect of the SrVO x film thickness on the transmittance characteristics of the multilayers is described and discussed. 1. Introduction Transparent conducting electrode (TCE) films are of significant importance for their use in ultraviolet (UV) optoelectronic devices, in- cluding UV photodetectors and UV light emitting diodes (LEDs), which are important for curing, sterilization, and space-to-space communica- tions [1–4]. Indium tin oxide (ITO) has served as common TCE [5–7] because it has resistivity lower than 10 -4 Ω cm and transmittance higher than 85% in the visible spectra [8–10]. However, ITO has low transmittance in the wavelength region below 400 nm (i.e., bandgap of ~3.7 eV) and its electrical properties are degraded when its thickness decreases [11,12], limiting its application in UV optoelectronic devices. Thus, to overcome these problems, it is vital to develop alternative electrodes with high transmittance and conductivity in the 200–400 nm region. UV transmittance increases as the energy bandgap (E g ) of op- tical materials increases. However, in most cases, large E g materials have low carrier concentrations because of difficulty in inter band transition [13–15]. To simultaneously improve the opto-electrical characteristics of TCEs, oxide/metal/oxide (OMO) multilayers have been utilized because the multilayers can prevent reflection from the mid-metal layer, serving as a conducting path [16,17]. As the mid- metal layer, silver (Ag) has been generally adopted because of its merits, including good conductivity and low optical loss due to low refractive index and extinction coefficient [17,18]. Further, a Ag layer combined with oxide layers having large dielectric constants could re- sult in zero reflection because this structure can suppress the surface plasmon effect [17,19]. Thus, a variety of OMO structures, such as Zn:SnO 2 /Ag/Zn:SnO 2 , TiO 2 /Ag/TiO 2 , ZnO/Ag/ZnO, and IGZO/Ag/ IGZO [16,20–22], have been investigated. These OMO multilayer samples produced Haccke's FOM [23] in the range of 94 × 10 -3 – 112 × 10 -3 Ω -1 . However, the improvement in the FOMs was achieved in the visible wavelength region, but not in the UV range. Thus, the development of UV conducting electrodes is vital for the development of UV opto-electrical devices. For this, Le and Lee [24] explored the opto-electrical properties of ZnMgBeO (ZMBO)/Ag/ZMBO samples and showed that the optimized ZMBO (30 nm)/Ag (10 nm)/ ZMBO (30 nm) samples gave resistivity of ~6.5 × 10 -5 Ω cm and transmittance of 74–90% in the 300–400 nm spectral region. It was also https://doi.org/10.1016/j.ceramint.2020.04.300 Received 12 March 2020; Received in revised form 23 April 2020; Accepted 30 April 2020 * Corresponding author. E-mail address: tyseong@korea.ac.kr (T.-Y. Seong). Ceramics International 46 (2020) 19484–19490 Available online 04 May 2020 0272-8842/ © 2020 Elsevier Ltd and Techna Group S.r.l. All rights reserved. T