A piezoresistive cantilever integrating an InAs-based semiconductor–superconductor junction

Targeting highly sensitive displacement and force sensors, we fabricated a piezoresistive cantilever that integrates a superconductor–semiconductor–superconductor (S–Sm–S) junction based on an InAs/AlGaSb heterostructure. The S–Sm–S junction is composed of a submicron Nb gap patterned on the InAs thin film, and a deflection of the cantilever is detected as a resistance change at the junction. We confirmed that the resistance change caused by induced strain (i.e., piezoresistance) has a strong dependence on bias current. When the maximum Josephson current (Ic) is biased to the junction, the resistance change is significantly enhanced by more than a factor of 10 compared to that at the bias current above Ic (the resistive state). The resulting maximum resistance change is 3.9 mΩ, which is three orders of magnitude larger than that obtained for our preliminary sample. This large piezoresistance at the S–Sm–S junction will lead to highly sensitive self-detective sensors.