The two carriersrsquo; mobilityhyphen;lifetime products and their light intensity dependencies in hydrogenated amorphous silicon

摘要

The effect of the equilibrium (or dark) occupation of the recombination centers on the majorityhyphen;carrier mobilityhyphen;lifetime mgr;tgr; product and its light intensity dependence have been discussed by Rose many years ago lsqb;ConceptsinPhotoconductivityandAlliedProblems(Wiley Interscience, New York, 1963), p. 22rsqb;. The corresponding theory is extended and it is discussed in terms of the energy separation between the equilibrium Fermi level and the energy levels of the recombination centers. The theory is then generalized to include the corresponding dependencies of the minorityhyphen;carrier mgr;tgr; product. The results are shown to be useful in analyzing the available phototransport data of hydrogenated amorphous silicon,ahyphen;Si:H, indicating that the lsquo;lsquo;standard defectrsquo;rsquo; model, which is widely used for the description of the electronic structure and the recombination processes in this material, cannot account for the phototransport data associated with the minority carrier. On the other hand the lsquo;lsquo;defect poolrsquo;rsquo; model, suggested more recently, is shown to be in accord with the available data.