Highly Sensitive Pressure Sensor Based on h-BN/Graphene/h-BN Heterojunction and Cu–Sn Solid–Liquid Interdiffusion Bonding
Junqiang Wang, Changzheng Xie, Mengwei Li, Jingyu Bai
Abstract
Graphene with atomic layer thickness has excellent mechanical properties and provides tremendous potential for developing high-performance pressure sensors. However, bare graphene is sensitive to humidity, and oxygen in the air also significantly affects the stability of graphene pressure sensor. In this work, a highly sensitive pressure sensor was fabricated through the MEMS process and nanofilm transferring. The graphene sensing element is entirely isolated from the external environment by the initial protection of h-BN, followed by the secondary protection of Cu–Sn solid–liquid interdiffusion bonding. After the static test, an average sensitivity of <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$2.9\times10$ </tex-math></inline-formula> <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">−4</sup> kPa <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">−1</sup> was achieved over a pressure range from −80 to 0 kPa. Also, it exhibited excellent repeatability and minimal hysteresis. As graphene pressure sensor was exposed to ambient air for 30 days, the relative resistance change was just 2.3%. The resistance of graphene pressure sensor can also keep stable even if the device was stored in a high-temperature or high-humidity environment. Thus, this work provides a promising approach for the practical application of high-performance graphene pressure sensors.