Electron mobility-lifetime product and D° defect density in hydrogenated amorphous silicon

The electron deep-trapping mobility lifetime product μτt and spin defect (D°) density Ns in hydrogenated amorphous silicon (a-Si:H) were studied using transient photocharge and electron spin resonance measurements. Three series of specimens were prepared in two different reactor geometries, with and without argon dilution of silane, and for varying substrate temperatures. For several specimens the effects of light soaking were also measured. For two of the series μτt was roughly inversely proportional to the spin density, in agreement with the model that electrons are deep-trapped by D° defects; these series yielded μτtNs ≈ 109cm−1V−1. For a third series of specimens a more rapid decline of μτt with Ns was observed.