Spherical Photovoltaic Device With Tailored Emitter Structure

The design and fabrication of a spherical photovoltaic device with a tailored emitter are presented. A reactive ion etching process is used to thin the emitter, providing a progressively varying junction depth and sheet resistance along the spherical surface. The surface of the transparent emitter is passivated by a silicon nitride layer to improve the spectral response and the photocurrent. The tailored variation in emitter depth is also shown to provide a lower ohmic loss path for the current, compared to a uniformly thinned emitter, where the high sheet resistance adds to the series resistance, thereby degrading the fill factor of the device.