Photoluminescence of microcrystalline silicon at low temperatures

Abstractauthoren Photoluminescence (PL) from semiconductors can be related with the quasi‐Fermi level splitting of the electron‐hole‐ensemble from which the radiation originates. For the interpretation of the temperature‐dependent μ c‐Si:H PL Planck's generalized law is extended and applied to describe the radiative recombination via band‐tail states. This substantial refinement of existing approaches allows for the modeling of temperature‐dependent spectra over the entire measured temperature range and furthermore provides access to the quasi‐Fermi level splitting (qFL) of electron‐hole ensembles in the thin film and furthermore yields quantitative information on band‐tail energies. In crystalline silicon, an increase in the quasi‐Fermi level splitting causes only an increase in the overall PL‐intensity, while the spectral shape of the spectrum is unaffected. In contrast, the PL‐spectra of μ c‐Si:H differ with varying qFL‐splitting both in intensity and shape. Only by introducing variations of qFL‐splitting and constructing an overall PL‐spectrum that is a superposition from excitation states with different qFL‐splittings, the experimental temperature‐dependent PL spectra from μ c‐Si:H can be reconstructed for the entire temperature range. Temperature‐dependent PL spectra of μ c‐Si:H silicon (symbols) and fits according to our proposed model (lines).