GaAs-based resonant tunneling diode (RTD) epitaxy on Si for highly sensitive strain gauge applications
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GaAs-based resonant tunneling diode (RTD) epitaxy on Si for highly sensitive strain gauge applications Jie Li1,2, Hao Guo1,2, Jun Liu1,2, Jun Tang1,2*, Haiqiao Ni3, Yunbo Shi1,2, Chenyang Xue1,2, Zhichuan Niu3, Wendong Zhang1,2, Mifeng Li3 and Ying Yu3
Abstract As a highly sensitive strain gauge element, GaAs-based resonant tunneling diode (RTD) has already been applied in microelectromechanical system (MEMS) sensors. Due to poor mechanical properties and high cost, GaAs-based material has been limited in applications as the substrate for MEMS. In this work, we present a method to fabricate the GaAs-based RTD on Si substrate. From the experimental results, it can be concluded that the piezoresistive coefficient achieved with this method reached 3.42 × 10−9 m2/N, which is about an order of magnitude higher than the Si-based semiconductor piezoresistors. Keywords: RTD epitaxy on Si, Strain gauge, Highly sensitive, Piezoresistive coefficient
Background In recent years, resonant tunneling diode (RTD) has attracted growing interest on the applications of highly sensitive strain gauge. Wen et al. explained this phenomenon as the meso-piezoresistance effect, which is the resonant tunneling current of the RTD tuned by the external mechanical strain [1]. Our previous study has already proved that the strain gauge sensitivity of the GaAs-based RTD can be one to two orders of magnitude higher than the traditional Si-based piezoresistive sensing elements [2-4]. Combining with the microelectromechanical system (MEMS) fabrication process on GaAs substrate, RTD has been fabricated as the embedded mechanical sensing element for different MEMS sensors: accelerometers [5] and hydrophone [6]. Compared to Si, GaAs is quite fragile, a property which limited its applications in the field of MEMS sensors especially as mechanical structures. Meanwhile, GaAs is quite expensive in terms of the material and fabrication process. To further expand the application fields * Correspondence: [email protected] 1 Key Laboratory of Instrumentation Science & Dynamic Measurement, North University of China, Ministry of Education, Shanxi 030051, China 2 Science and Technology on Electronic Test & Measurement Laboratory, North University of China, Taiyuan, Shanxi 030051, China Full list of author information is available at the end of the article
of the excellent performances of GaAs-based mechanical sensing element, it is quite necessary to combine the highly sensitive GaAs-based strain gauge elements with the Si substrate. Due to lattice mismatch, GaAs is quite difficult to be fabricated on Si substrate [7]. Researchers have already worked for many years to combine the advantage of Si-based materials with other semiconductor materials for application in microelectronics and photonics, and different technologies have been reported: direct GaAs-on-Si epitaxy, GaAs-on-Si growth through Ge buffer layers, GaAs-on-SOI epitaxy, GaAs-on-STO-Si epitaxy, bonding, etc. [8-10]. From the literatures reported, it can be concluded that diff
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