Giant Resistivity Change of Transparent ZnO/Muscovite Heteroepitaxy

Abstract

The piezoresistive effect has shown a remarkable potential for mechanical sensor applications and been sought for its excellent performance. A great attention was paid to the giant piezoresistive effect and sensitivity delivered by silicon-based nanostructures. However, low thermal stability and complicated fabrication process hinder their practical applications. To overcome these issues and enhance the functionalities, we envision the substantial piezopotential in a zinc oxide (ZnO)/muscovite (mica) heteroepitaxy system based on theoretical consideration and realize it in practice. High piezoresistive effect with giant change of resistivity (−80 to 240%) and large gauge factor (>1000) are demonstrated through mechanical bending. The detailed features of heteroepitaxy, electrical transport, and strain are probed to understand the mechanism of such a giant resistivity change. In addition, a bending model is established to reveal the distribution of strain. Finally, we demonstrate a flex sensor featuring high sensitivity, optical transparency, and two-segment sensing with a great potential toward practical applications. Such an oxide heteroepitaxy exhibits excellent piezoresistive properties and mechanical flexibility. In the near future, the importance of flex sensors will emerge because of the precise control in the automation industries, and our results lead to a new design in the field of flex sensors.

Fabrication of Large-Scale High-Mobility Flexible Transparent Zinc Oxide Single Crystal Wafers

“…The functionality is shown in Figure d; with the decrease in the bending radius, the resistance of piezoresistive ZnO/ZnO FSCW decreases and increases monotonically under flex-in and flex-out modes, respectively. The changes in the resistance are −68 and 241% in both flex-in and flex-out modes at a bending radius of 7 mm, similar to the previous study of ZnO/muscovite . This bending creates a strain gradient-induced piezopotential resulting in the piezoelectric and piezoresistive coupling and the corresponding resistance change.…”

“…As a semiconductor wafer, standard semiconductor manufacturing processes, such as patterning, etching, deposition, and doping, will be implemented to build up the device. Thus, to demonstrate such feasibility, a homojunction by depositing a piezoresistive ZnO thin film on the insulating ZnO FSCW 33 was fabricated for the application of a flex sensor. The functionality is shown in Figure 5d; with the decrease in the bending radius, the resistance of piezoresistive ZnO/ZnO FSCW decreases and increases monotonically under flex-in and flex-out modes, respectively.…”

“…The changes in the resistance are −68 and 241% in both flex-in and flex-out modes at a bending radius of 7 mm, similar to the previous study of ZnO/muscovite. 33 This bending creates a strain gradient-induced piezopotential resulting in the piezoelectric and piezoresistive coupling and the corresponding resistance change. To confirm the robustness of the homojunction, the associated bending tests were conducted to demonstrate its mechanical stability.…”

All‐inorganic flexible high‐temperature strain sensor based on SrRuO3/muscovite heteroepitaxy

“…22,23 However, growing functional layer on high temperature tolerant flexible muscovite (mica) is one of the most promising strategies to fabricate the all-inorganic strain sensors. [23][24][25] Mica, KAl 2 (Si 3 Al)O 10 (OH) 2 , is a layered silicate structure. The basic structure of mica is composed of two silicate tetrahedral (SiO 4 ) sites and an aluminum octahedral (AlO 6 ) site, which are bound by interlayer cations (K + ).…”

“…Guo and coworkers have prepared flexible strain sensors based on La 0.7 Sr 0.3 MnO 3 (LSMO)/mica 21 and BaNb 0.5 Ti 0.5 O 3 (BNT)/mica, 23 but these films are all polycrystalline and have relatively low sensitivity. Although the single-crystal ZnO deposited on mica by Yen et al 25 has a huge resistive tunability, it is easy to absorb water during use and is not easy to be packaged.…”