TEMPERATURE-DEPENDENCE OF THE DIELECTRIC FUNCTION OF SI

A method is described for calculating the real (epsilon-1) and imaginary (epsilon-2) parts of the dielectric function of Si for temperatures between 30 and 793 K and for photon energies ranging from 1.7 to 5.7 eV. The model reveals distinct structures at energies of the E1 [two-dimensional (2D) M0 critical point (CP)], E2 [a mixture of damped harmonic oscillator (DHO) and 2D-M2 CP], E'0, and E'1 (DHO). The Kramers-Kronig transformation is employed in developing the 2D-M2 CP model. Since the excitonic effects profoundly modify the E1-gap CP structure at low temperatures, the model also accounts for the excitonic effects at this CP. Results are in satisfactory agreement with the experimental information over the entire range of photon energies. The temperature dependence of the strength and broadening parameters at each CP are also given and discussed.