Research on High-Bandgap Materials and Amorphous Silicon-Based Solar Cells: Annual Technical Report, 15 May 1995 - 15 May 1996

In this report, the researchers present a technique for using modulated electroabsorption measurements to determine the built-in potential in semiconductor heterojunction devices. The technique exploits a simple relationship between the second-harmonic electroabsorption signal and the capacitance of such devices. The researchers apply this technique to hydrogenated amorphous silicon (a-Si:H)based solar cells incorporating microcrystalline Si p+ layers. For one set of cells with a conventional plasma-deposited intrinsic layer, they obtain a built-in potential of 0.98-0.04V; for cells with an intrinsic layer deposited using strong hydrogen-dilution, they obtain 1.25-0.04 V. The researchers speculate that interface dipoles between the p+ and intrinsic layers significantly influencethe built-in potential.