Optical determination of mobility and carrier concentration in heavily doped polycrystalline silicon

Abstract

Optical absorption of phosphorus-doped polycrystalline Si films observed at photon energies below the energy gap has been interpreted in terms of free-carrier absorption, which obeys the Drude theory. As a result, we can simultaneously determine conductivity, electron mobility, and carrier concentration of heavily doped polycrystalline Si films from their optical transmission spectra alone. The new technique offers a contactless measurement of electrical properties for heavily doped polycrystalline Si thin films.