3PA-TCT in SiC

This work presents the first experimental demonstration of the Three-Photon Absorption Transient Current Technique (3PA-TCT) in silicon carbide (SiC) detectors. By employing a femtosecond laser operating at 800 nm—corresponding to the fundamental wavelength of the laser system—localized charge generation is achieved through simultaneous absorption of three photons, enabling deep-substrate excitation without requiring frequency conversion. The experimental setup is significantly simplified compared to standard TPA-TCT, with moderate pulse energies and reduced surface photoabsorption (SPA) interference. A cubic dependence of the signal strength on laser intensity confirms the 3PA mechanism. Depth-resolved scans were performed on both non-irradiated and neutron-irradiated p-in-n SiC pad diodes, revealing clear signals and electric field dependence. The method demonstrated excellent spatial selectivity and robustness even after high-fluence irradiation (1×1015 neq/cm21 \times 10^{15}\,\text{n}_{\text{eq}}/\text{cm}^21×1015neq/cm2). These results open the door to compact, table-top 3PA-TCT systems using standard telecom and Ti:sapphire lasers, and represent a promising direction for wide bandgap semiconductor detector characterization.