Deep-level sensitization in Ge-SiO2 composite films observed by photocurrent spectroscopy

We studied the temperature dependence of the photocurrent spectra of a Ge-SiO2 composite thin film. We found that the spectral position of the photocurrent peak is determined by the competition between absorption and non-radiative recombination and that its temperature dependence is associated with the population variation of the energetically deep levels in the system under “thermal quenching” conditions. Combining these results with our previous deep-level transient spectroscopy data enables the association of these levels with the quantum confinement effect. We thus identify here a non-radiative recombination process associated with deep-level sensitization that stems from quantum confinement.