Microcrystalline silicon thin films using DC saddle-field glow discharge

Microcrystalline silicon (muc-Si:H) thin films offer the potential of increased stability against photoinduced degradation, improved spectral utilization in all silicon multi-junction amorphous-microcrystalline solar cells, and efficient doping. Recently we have prepared mucSi:H films, consisting of crystalline grains embedded in an amorphous network, using the dc saddle-field glow discharge deposition method. Increasing presence of microcrystallinity with decreasing silane concentration has been observed with Raman spectroscopy. Electron diffraction, TEM and HRTEM examination confirms the presence of nanocrystallites of Si. Optical measurements show an increase in the Tauc gap from about 1.9 eV to 2.5 eV with decreasing silane concentration. Doping studies show that n-doped microcrystalline silicon can have electrical resistivity of less than 1 Omega cm. Application to photovoltaic devices shows potential for a significant improvement in solar cell performance.