Probing Silicon Carbide with Phase-Modulated Femtosecond Laser Pulses: Insights into Multiphoton Photocurrent

Abstract

Wide-bandgap semiconductors are widely used in photonic technologies due to their advantageous features, such as large optical bandgap, low losses, and fast operational speeds. Silicon carbide (SiC) is a prototypical wide bandgap semiconductor with high optical nonlinearities, large electron transport, and a high breakdown threshold. Integration of SiC in nonlinear photonics requires a systematic analysis of the multiphoton contribution to device functionality. Here, the multiphoton photocurrent in a SiC photodetector is investigated using phase-modulated femtosecond pulses. Multiphoton absorption is quantified using a 1030 nm phase-modulated pulsed laser. Our measurements show that although the bandgap is less than the energy of three photons, only four-photon absorption has a significant contribution to the photocurrent. We interpret the four-photon absorption as a direct transition from the valence band to the conduction band at the Γ point. More importantly, SiC withstands higher excitation intensities compared to other wide bandgap semiconductors, making it an ideal system for high-power nonlinear applications.