The hydrogen collision model: theory and experiment

Abstract The H collision model of the Staebler–Wronski effect in hydrogenated amorphous silicon attributes light- and carrier-induced metastability to the association in pairs of mobile H that have diffused long distances after excitation from Si–H bonds. This microscopic model is consistent with the constraints imposed by electron spin resonance and other experiments. Mobile H density is the key variable of the quantitative theory describing metastable dangling-bond creation. As predicted, pulsed illumination experiments show that there is an intermediate precursor between electron–hole recombination and metastable dangling-bond (DB) creation. I suggest this precursor is mobile H, whose density normally requires about a millisecond to respond to changes in illumination. The numerical constants describing H emission and trapping within the H collision model are estimated from recent pulsed-illumination experiments. A representative numerical solution of the model is shown.