Photo-induced Absorption Spectroscopy
Photo-induced absorption (PIA) is a spectroscopic technique where small changes in the absorption coefficient in the presence of a modulated-monochromatic light source indicate the presence of carriers with a semiconductor conduction band. In the temporal regime PIA can be used to study excited state dynamics including carrier transport temperatures, inter-band transitions, and photo bleaching. Variations in the modulation frequency leads this technique to be sensitive to the bulk recombination coefficient in a semiconductor, allowing for a direct probe of the bi-molecular recombination.
Our home-built PIA setup is comprised of an Oriel TLS-260 monochromatic light source and various continuous wave laser diode as probe and pump respectively. This system is sensitive to PIA between 300-1200 nm and can be used to probe for both steady state carrier distributions as well as frequency dependent bi-molecular recombination dynamics.