Fabrication of optically enhanced thin film a‐SiH_x solar cells

Fabrication methods used to produce the first optically enhanced thin film solar cells are described. Optically enhanced 0.6–1 μm thick a‐SiH_x solar cells have been fabricated which yield short circuit currents ∼3 mA/cm² greater than comparable unenhanced cells. This respresents a ∼20% improvement in the short circuit current and is due to trapping of weakly adsorbed photons in the semiconductor that have been scattered by textured surfaces within the cell. Texturing of the cell must be such that light is efficiently scattered, and the roughness must not produce shorting of the front surface transparent conductor with the rear electrical contact. To produce the required texture, thin film solar cells are deposited on the surface of substrates patterned with microstructures created using a new lithographic method (natural lithography). Other considerations for fabrication of enhanced PIN a‐SiH_x cells include (1) production of reflector geometrics which minimize parasitic optical absorption and (2) creation of a carrier collection width nearly equal to the cell thickness.