Large-area germanium dendritic TPV cells

The primary object of the work was to demonstrate the feasibility of fabrication of TPV cells of several square cm of area on germanium web, which can be grown at 1-cm widths in lengths of several meters. Such cells were successfully made, but have not as yet attained the performance afforded by other cells of conventiorLal manufacture. The first efforts concerned alloyed-junction cells. Small area diodes were made in this way, but difficulties with non-uniformity of alloy wetting over large areas prevented the fabrication of acceptable large-area devices. Attention was therefore given to diffused junctions, and an open-tube gallium diffusion process was developed by which large-area diodes could readily be made. These were used as front-junction cells with vacuum-deposited titanium-silver contacts. The largest device evaluated was 0.8 cm × 9.5 cm.