Structural and electrical characterization of microcrystalline silicon films prepared by a layer-by-layer technique with a plasma-enhanced chemical-vapor deposition system

摘要

Microcrystalline silicon films have been prepared on indium-coated glass utilizing a layer-by-layer technique with a plasma-enhanced chemical-vapor deposition system. The microcrystalline films were fabricated by varying the number of cycles from 10 to 60 under a fixed H_(2) time (t_(2)) of 120 s, where the corresponding deposition time (t_(1)) of amorphous silicon thin film was 60 s. Structural properties, such as the crystalline volume fraction (X_(c)) and grain sizes were analyzed by using Raman spectroscopy and a scanning electron microscopy. The carrier transport was characterized by the temperature dependence of dark conductivity, giving rise to the calculation of activation energy (E_(a)). Optical energy gaps (E_(g)) were also investigated using an ultraviolet spectrophotometer. In addition, the process under different hydrogen plasma time (t_(2)) at a fixed number of 20 cycles was extensively carried out to study the dominant role of hydrogen atoms in layer-by-layer deposition. Finally, the correlation between structural and electrical properties has been discussed on the basis of experimental results.