Fast light-induced metastability and thermal recovery for protocrystalline silicon multilayers proved by sub-bandgap absorption spectra

Light soaking and thermal annealing behaviors of an alternately hydrogen-diluted hydrogenated protocrystalline silicon (pc-Si:H) multilayer are investigated using a constant photocurrent measurement. The pc-Si:H multilayer includes isolated nano-sized silicon (nc-Si) grains embedded in a hydrogenated amorphous silicon (a-Si:H) matrix with a vertically regular distribution. A wide optical bandgap of the pc-Si:H multilayer is inspected mainly due to an non-uniform hydrogen distribution and quantum size effect. Compared to a conventional a-Si:H film, the pc-Si:H multilayer exhibits a superior light-induced metastability with a fast stabilization and low degradation. In addition, the pc-Si:H multilayer shows a reversible thermal recovery in a short annealing time.