Piezo-spectroscopy is a technique to understand how the mechanical stress can affect the optical and mechanical properties of materials. When the system scales down from bulk to nanostructures, a instrumental effort is required.
The Laser-atom probe tomography (La-APT) is a technique used to study the structure of nano-systems with needle shape and an apex radius (<100nm), under a high electric field at their apex (>10 V/nm). Pulsed laser radiation triggers the ion evaporation from the specimens and activates the emission from optically active centers present into the material. Diamond needles were studied and the influence of the electric field on the fine structure of some color centers were observed. The first study focused on the neutral nitrogen-vacancy center (NV0) which allowed to evaluate the mechanical stress (>1GPa) and the electric-field acting on diamond tips. These results demonstrated an original new method to perform contactless piezo-spectroscopy of nanoscale systems under uniaxial tensile stress generated by the electric field. Another color center, emitting at 2.65eV and more sensitive than the NV0 color centers to the stress/strain field, was studied through this new technique and new results on the opto-mechanical properties of this center were achieved.
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