Photoexcitation and Decay of Higher Order Bands in Neutron Irradiated Silicon

The optically induced excitation and decay processes of the higher order bands in fast neutron irradiated silicon have been investigated in detail using Fourier transform infrared spectrometer at low temperatures with a variety of illumination intensity. It is found that the excitation process follows an exponential time dependence and the decay follows a logarithmic. The present results suggest that the characteristic of the optically active of the higher order bands is associated with the slow relaxation of photoexcited carriers.