Optical properties of microcrystalline materials

We use optical, photocurrent and photothermal deflection spectroscopies to study defects in microcrystalline silicon Ž . mc-Si thin films and diamond layers. Enhanced light absorption in mc-Si films and solar cells is due to several contributions: light scattering, change in the optical transition probability for strained and surface atoms and residual Ž y1 amorphous fraction. Low defect density optical absorption with a coefficient, a , smaller than 0.1 cm at about 0.8 eV, as . measured by the constant photocurrent method , amorphous volume fraction below 10% and a distinct surface texture is typical for a material yielding a good efficiency mc-Si solar cells. Main defects in heteroepitaxial chemical vapor deposition diamond films are discussed.