Growth of hydrogenated microcrystalline silicon (μc-Si:H) films by HWCVD using a Graphite catalyzer

A graphite catalyzer has been used to grow muc-Si:H films using the thermo-catalytic (HW) chemical vapor deposition (CVD) technique. The films grown in the amorphous-microcrystalline transition regime' have been found to exhibit a high photosensitivity of the order of 10(2-)10(3) at a crystalline volume fraction of 0.2-0.4. The effects of deposition parameters such as silane concentration, pressure and substrate temperature on the microstructure and electrical properties of the films have been studied. It has been found that the graphite catalyzer offers a wider window of the deposition parameters for the growth of the 'transition regime' films as compared to the conventional W and Ta catalyzers. In addition, the graphite wires also exhibit significantly greater chemical as well as mechanical stability than the W and Ta wires, which results in improvement of the reproducibility of the technique. However, at the same filament temperature and other conditions, the deposition rates are about 10 times lower than for W or Ta filament. Increasing of the filament temperature, on the contrary, lead to radiative heating and carbon contamination of the growing film.