Optimization of the piezoresistive AFM cantilever design for use at cryogenic temperatures

We have developed heavily boron-doped piezoresistive single-crystalline silicon AFM cantilevers for operation at low temperatures, including the cryogenic temperature range. The optimization of the design to increase sensitivity and reduce noise at cryogenic temperatures is considered by controlling the dopant concentration. The relatively low concentration of 6×1018 atoms/cm3 shows the lowest minimum detectable force (MDF) at room temperature (RT) by calculation. However, it was predicted by calculation that the optimal concentration of dopant for MDF was shifted to a higher concentration at cryogenic temperatures. First, we developed AFM cantilevers integrated with piezoresistive elements at the support of the cantilever. The actual fabricated heavily doped cantilever shows that the sensitivity at cryogenic temperature increased by 1.6 times at 5 K compared to that at RT.