Optical constants of rf sputtered hydrogenated amorphous Si

Abstract

The transmission spectra of $a\ensuremath{-}{\mathrm{Si}}_{1\ensuremath{-}x}{\mathrm{H}}_{x}$ alloys prepared under various combinations of substrate temperature ${T}_{s}$ and hydrogen partial pressure ${p}_{\mathrm{H}}$ have been measured over the region of the spectrum encompassing the absorption edge. The dependence of the refractive index on ${T}_{s}$ and ${p}_{\mathrm{H}}$ and the photon energy has been established. The displacement of the absorption edge with ${T}_{s}$ and ${p}_{\mathrm{H}}$ has been studied and related to the hydrogen content of the films and the detailed parameters of deposition. Changes in the absorption edge spectrum resulting from annealing have been correlated with the evolution of hydrogen. The addition of P and B dopants produces absorption at photon energies below the edge of the undoped material. Finally, the temperature dependence of the absorption edge between 4 and 300 K has been measured.