Photothermal dynamics in functionally graded semiconductors with size-dependent effects under pulsed laser excitation

This study investigates the photothermal behavior of nonlocal, functionally graded (FG) semiconductor materials under ultra-short pulsed laser heating, addressing a critical gap in understanding the interplay of plasma, thermal, and elastic waves. Limited research has explored the combined effects of spatio-temporal nonlocality, FG material properties, and photothermal interactions under pulsed laser excitation in transient conditions. The novelty of this work lies in integrating spatio-temporal nonlocal elasticity theory with the Green–Naghdi (GN-II) thermoelasticity model, which accounts for non-Fourier heat conduction without energy dissipation, and modeling material properties with a power law distribution for advanced semiconductor applications. The research formulates governing equations for a two-dimensional, transversely isotropic FG semiconductor with exponentially varying properties, employs normal-mode analysis to derive exact solutions for displacement, temperature, carrier density, and thermal stresses, and uses numerical simulations to assess the influence of thermoelectric coupling, carrier lifetime, and transient time under non-Gaussian laser pulses and surface recombination boundary conditions. Results show that nonlocal and photothermal effects markedly alter thermal and mechanical responses: thermoelectric coupling reduces temperature and stress magnitudes while increasing displacement, and the GN-II model predicts finite heat-wave speeds consistent with experimental observations. Variations in carrier lifetime and time strongly influence all field variables, underscoring their critical role in dynamic behavior. These findings offer valuable insights for optimizing thermal management in microelectronics and optoelectronic devices and have practical implications for laser-based material processing and non-destructive testing.