Charge Carrier Relaxation after Subbandgap Excitation in Doped a-Si:H

Charge carrier dynamics in doped and undoped a-Si:H after subbandgap excitation at 1064 nm was followed by transient photoconductivity experiments. The kind of optical transitions induced by 1064 nm light is strongly dependent on the position of the Fermi-level. This allows the seperation of excess electron and excess hole kinetics as in n-doped samples mainly mobile electrons and in moderately p-doped samples mainly free holes are generated by 1064 nm light. From comparison of the photoconductivity after 532 nm and 1064 nm excitation it is inferred that the rate controlling step for the electron decay is the availability of free holes.