Metastability studies in silicon thin films: From short range ordered to medium and long range ordered materials

The effects of disorder on the kinetics of creation of metastable defects on silicon thin films have been studied through the evolution of the dark conductivity, the photoconductivity and the subgap absorption. Hydrogenated amorphous silicon, representative of short range ordered materials has been compared to polymorphous silicon (medium range order) and to microcrystalline silicon (long range order). Changing from short range ordered to medium range ordered materials results in a faster kinetics of creation of metastable defects as well as to films with better properties in both as-deposited and light-soaked states. Microcrystalline silicon films with crystalline fractions above 60% present stability and an improvement of their properties during light-soaking.