Conductive Domain-Wall Temperature Sensors of LiNbO<sub>3</sub> Ferroelectric Single-Crystal Thin Films
Wenping Geng, Jinlong He, Xiaojun Qiao, Liya Niu, Caiqin Zhao, Gang Xue, Kaixi Bi, Linyu Mei, Xiangjian Wang, Xiujian Chou
Abstract
Domain wall current (DWC) plays a key role in storage devices, logic devices and sensors due to its high on-off ratio and nano structure size in the era of nanoelectronics technology. In this work, the DWC of single crystal LiNbO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sub> thin film was studied by piezoresponse force microscope (PFM) and conducting atomic force microscope (c-AFM). We mainly focus on voltage and temperature dependence of DWC which increases with the voltage and temperatures. Based on this research, the packaged DWC temperature sensor is fabricated and applied in wide temperature range. The existence of domain walls makes the current on-off ratio as high as 10 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sup> at the voltage of 15 V. Our study shows that DWC has a negative temperature coefficient (NTC) from 140 K to 500 K. The current increases from 3 pA to <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$57 ~\mu \text{A}$ </tex-math></inline-formula> , which is attributed to the conductivity of switched domain. This work proposes a new type temperature sensor with wide temperature range and high compatibility and sensitivity. In addition, it provides support for harsh environment applications of ferroelectric domain engineering devices.