Laser-induced anisotropic thermoelectric voltages in thin films

Transverse thermoelectric voltages have been observed to occur when thin Mo and W films are excited by pulsed laser light at normal incidence to the film. Wavelengths in the range 0.46–1.06 μm and pulse widths of ∼ 3–300 nsec were used. A maximum thermoelectric voltage of ∼50 mV occurring across a load resistance of 50 Ω for an ∼ 1-kW incident laser pulse has been observed. A correlation between intrinsic film stress and output voltage suggests that the stress gives rise to a nonscalar absolute thermoelectric power (Seebeck coefficients) even though the transport properties of these bulk materials are isotropic.