Photo-Induced Tellurium Segregation in MoTe₂

Herein, coherent phonon spectroscopy of polymorphic (Formula presented.) single crystals using a femtosecond-pulsed laser is used to investigate the relationship between structural phase transitions and photo-thermal effects induced by high-density laser excitation. Even when a femtosecond-pulsed laser is used, which generally induces fewer heat accumulation effects than the case for a continuous-wave (CW) laser, tellurium segregation is observed in coherent phonon spectra with increasing excitation density, while no structural phase transition among the polymorphs of (Formula presented.) is observed. The use of higher photon-energy excitation, however, is found to suppress tellurium segregation.