Nanosens 

The goal of this project is to significantly improve the performance of non contact atomic force microscopy (NC-AFM) by developing new force sensors (or cantilevers). 

In NC-AFM, the minimal detectable force is inversely proportional to the square root of the resonance frequency and the quality factor. Improving the instrument sensitivity can then be done by increasing the resonance frequency and/or the quality factor of the CL. 

Increasing the resonance frequency of CL while keeping the stiffness at values compatible with NC-AFM requires a decrease of the effective mass of the device, hence a size reduction. Here, we aim at developing CLs with submicronic dimensions from monocrystalline silicon carbide 3C-SiC films grown on Si. The excellent mechanical properties of SiC, combined with the small size of these devices allow reaching resonance frequencies as high as 100 MHz, leading to a 100-fold increase relative to the cantilevers in use presently. 

The small size of these nano-cantilevers (typically 3 x 1 x 0.4 μm³) disqualifies the usual optical techniques (beam deflexion or interferometric methods) for measuring their motion. The method to detect the CL displacement will be based on the strain-induced variations of the resistance of a thin metallic film deposited on the cantilever. This metallic piezoresistivity based approach is radically different from the semiconducting piezoresistivity based approach that has been developed and used for about 10 years for AFM CLs. 

This project gathers in the same consortium experts in SiC thin film growth and polishing, in SiC based MEMS and NEMS and finally in NC-AFM instrumentation and modelling.