Microcrystalline and "micromorph" solar cells and modules: status and potential

Motivation and scope for introduction of microcrystalline silicon within thin-film silicon solar cells is described. Requirements for intrinsic layers in microcrystalline silicon solar cells are listed. The concept of a μc-Si:H/a-Si:H or "micromorph" tandem solar cell is presented, together with factors limiting efficiency increase, and above all J_sc. To increase J_sc, it is necessary to increase light trapping and reduce optical absorption in contact and reflector layers. Costs associated with module production are strongly influenced by the investment for plasma deposition. To reduce costs, use of professional production equipment and deposition rate increase are critical elements. For the latter, PE-CVD with higher deposition pressures has so far been the most successful method.