Investigation of the thermal charge “trapping-detrapping” in silicon nanocrystals: Correlation of the optical properties with complex impedance spectra

The charge confinement in silicon nanocrystals over the temperature range 35–300 K was investigated by complex impedance spectroscopy (CIS). A charge response found in the “dark” (i.e., no laser pumping) CIS spectrum indicated a frequency shift with temperature, which was well correlated with the temperature dependent photoluminescence (PL) intensity. From equivalent circuit analyses of this frequency shift, we were able to determine the charge “trapping-detrapping” mechanism giving rise to the luminescence. We find that the luminescence decay transient, expressed as a stretched exponential function, can be mathematically converted to a CIS spectrum.