Memory effect of sol–gel derived V-doped SrZrO 3 thin films Chih-Yi Liu a , Chun-Chieh Chuang a , Jian-Shian Chen a , Arthur Wang b , Wen-Yueh Jang b , Jien-Chen Young b , Kuang-Yi Chiu b , Tseung-Yuen Tseng a, * a Department of Electronics Engineering and Institute of Electronics, National Chiao-Tung University, Hsinchu 300, Taiwan b Winbond Electronics Corp., Hsinchu 300, Taiwan Available online 6 September 2005 Abstract V-doped SrZrO 3 (SZO) thin films on LaNiO 3 /SiO 2 /Si substrate are synthesized by sol – gel method to form metal – insulator – metal (MIM) sandwich structure. The physical and electrical properties of the MIM device are studied. The structure and surface morphology of the SZO films are also characterized by X-ray diffraction and scanning electron microscopy. Such a device has the bistable switching properties of current – voltage characteristics. The resistive switching between high state and low state can also be operated with voltage pulses. The device with the properties of long retention time and non-destructive readout is expected to be suitable for nonvolatile memory application. D 2005 Elsevier B.V. All rights reserved. Keywords: SrZrO 3 ; Memory effect; Nonvolatile memory; RRAM 1. Introduction Following the popularity of portable equipments, such as mobile phone, digital camera, and notebook computer, nonvolatile memory becomes one of the mainstreams of semiconductor industry. The nonvolatile memory device should keep the stored information for a long time without requiring power supply. The criteria for a perfect nonvolatile memory device include low operation voltage, low power consumption, long retention time, small cell size, high operation speed, low cost, high endurance, non-destructive readout, and simple structure [1]. However, so far there is no nonvolatile memory device that satisfies all these require- ments. Although flash memory is the mainstream among the nonvolatile memory devices nowadays, it has many draw- backs including high operation voltage, low operation speed, and poor endurance. In addition, as the device is continuously scaled down in size, the flash memory faces the challenge of gate oxide thinning that causes the unsatisfactory retention time. Therefore, many nonvolatile memories are eagerly investigated to replace flash memory. Resistance random access memory (RRAM) is one of the promising candidates for the next generation nonvolatile memory application. Perovskite materials are investigated for many applications, such as gate dielectrics [2], dynamic random access memory (DRAM) [3], and tunable microwave device [4]. Recently, Beck et al. proposed that Cr-doped SrZrO 3 (SZO) film had reversible bistable switching properties and was suitable for nonvolatile memory application [5]. We adopted the oriented LaNiO 3 film as the bottom electrode for the considerations of low cost and low process temperature. In this paper, we used the sol–gel method to deposited V-doped SZO films to investigate their electrical and physical properties. Sol – gel method has the advantages that include low cost, easy stoichiometric control, and high uniformity. The influence of process conditions of thermal treatment on the physical properties of the films was also investigated. The V-doped SZO film was found to have the reversible switching behavior and the memory effect. 2. Experimental procedures The 4-in. boron-doped p-type (100) silicon wafer was adopted as substrate for device fabrication. After the standard Radio Company of America (RCA) cleaning, the 0040-6090/$ - see front matter D 2005 Elsevier B.V. All rights reserved. doi:10.1016/j.tsf.2005.08.153 * Corresponding author. Tel.: +886 3 5731879; fax: +886 3 5724361. E-mail address: tseng@cc.nctu.edu.tw (T.-Y. Tseng). Thin Solid Films 494 (2006) 287 – 290 www.elsevier.com/locate/tsf