The diffusion process of metastable carriers in bismuth

The diffusion process of electrons and holes which have been pumped into a metastable band in bismuth films by a 1.064-μm laser pulse is considered in the calculation of the induced thermal gradient. The fit between the temporal evolution of this calculated thermal gradient and that of the thermoelectric response of films to the laser excitation allows us to estimate an upper limit of the ambipolar diffusion coefficient of metastable carriers.