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 ( I c ) 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 I c (the resistive state). The resulting maximum resistance change is 3.9 m Ω , 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.