Internal contacts to photovoltaic structures using ion beam milling

Characterization of individual junctions within a multilayered semiconductor structure is beneficial to understanding overall performance. Ion beam milling with masks to profile selected areas, followed by metallization, is used to make internal contacts to multilayered photovoltaic structures. Junctions deep within the structure may be analyzed using a straightforward model tested previously on the nSi/SnO₂/CdSe/electrolyte tandem solar cell. Internal contacts are made to the CdS/CuInSe₂/Mo thin film solar cell. In this type of cell, an undesirable Schottky barrier may occur at the CuInSe₂/Mo interface; its effects should be separated from those of the primary CdS/CuInSe₂ barrier. In addition to specific results, problems and limitations of the technique are discussed.