Investigations Into Near Infrared Sensitive Solar Cells
In the solar industry today many new endeavors rely on improving efficiency on existing solar technologies such as silicon and gallium arsenide based solar cells. Other new technologies tend to lean towards cadmium or organic based devices in an attempt to produce more effective, less costly solar devices. While this is good for business and growth, the underlying problem of improving efficiency will not be solved by staying in a low cost box of a handful of choices. This research is focused outside this material box by looking into improving the hybrid multi-junction silicon germanium (HMJ-SiGe) solar cell structure, a germanium based solar cell device. An antimony doped germanium substrate is used in conjunction with germanium telluride, in an approximate 1:1 ratio in order to produce a functional solar cell device. Using standard processing techniques already in use in the commercial industry, samples are created and tested using solar simulator, spectroscopic equipment and standard electronics testing equipment. Layering germanium telluride on top of a doped germanium sample, followed by contacts and an anti-reflective layer of silicon nitride allowed for a functional solar cell producing 103.7mV and 470 uA developing a 0.049 efficient device. These results show that a device is feasible, however more research into improving efficiency and lowering costs are required before it can be adapted for use in other device structures.