Independent regulation of electrical properties of VO2 for low threshold voltage electro-optic switch applications

作者：Qi, Jiahua; Zhang, Dongping^*; He, Qicong; Zeng, Lanxuan; Liu, Yi; Wang, Zhuangbing; Zhong, Aihua; Cai, Xingmin; Ye, Fan; Fan, Ping

来源：Sensors and Actuators, A: Physical , 2022, 335: 113394.

DOI：10.1016/j.sna.2022.113394

• Vanadium dioxide
• Metal insulator transition
• Threshold voltage
• Optical switch

Vanadium dioxide has a unique insulator-metal phase transition characteristic near room temperature, meeting optical switches' requirements. However, due to its high resistance in the insulator state, the working voltage threshold of the VO2-based optical switch is also high. It is one of the obstacles for VO2-based optical switch applications. In this work, high-quality VO2 films were prepared by DC pulsed magnetron sputtering. By inserting a conductive ITO buffer layer, VO2 sheet resistance reduced about 2 orders, and the electrical phase change characteristics have almost disappeared. Still, the high optical modulation ability is hardly affected. The interesting results meet the requirements of a low threshold working voltage electro-optic switch. In the case of a 40 mu m electrode gap size, the threshold voltage for VO2/ITO is only 1.4 V, which is much lower than 20 V of pure VO2 in the same condition, and the optical switch modulation depth at the wavelength of 1550 nm reaches 35%. For the switch with 5 mu m electrode gap size, the threshold voltage is only 1.3 V, and the response times of "ON " and "OFF " are 0.24 ms and 2.1 ms, respectively. This result is valuable for the practical application of VO2-based optical switches.