Abstract
Lifetime resolved measurements of photoluminescence (PL) have been done under pulsed excitation for a-Si:H based films including those having nanometer sized structure. The results of the lifetime resolved PL are understood by considering two components. We observed a component of lifetimes longer than 1 μs which is considered to be due to localized electron-hole pairs. Another component was observed around 10 ns in the lifetime distributions. In the case of a-Si:H the PL is dominated by the longer lifetime component and the 10 ns component is observed only for high energy PL. On the other hand, the 10 ns component is dominant and stable against raising temperature in the case of the films in which the confinement effect of electrons and holes is significant. In the case of a-Si1-xNx:H alloy films, the 10 ns component is also dominant and stable against raising temperature. These results suggest that the 10 ns component is due to singlet excitons being stable by confinement effect or decreasing dielectric constant. These results are also consistent with triplet exciton model which was used to explain the results of lifetime resolved PL in millisecond region in a-Si:H based films in our previous paper.
