Mobility-lifetime products in hydrogenated amorphous silicon

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Abstract
The most important parameters characterizing the photoelectronic quality of a semiconductor are its charge-carrier mobility lifetime, μτ, products. The two common experimental methods used to determine these parameters in hydrogenated amorphous silicon, a-Si:H, are the steady-state photoconductivity measurement and the life-of-flight charge-collection measurement. The two methods yield quite different results. We show that the difference can be resolved by an understanding of the physics involved in each of the measurements. We show that the steady-state μτ is expected to be up to three orders of magnitude larger than the time-of-flight μτ in undoped a-Si:H. This prediction is in excellent agreement with the corresponding experimental results.