Properties like high efficiency, flexibility and light weight, resistance to UV radiation and moisture and a coffee temperature coefficient make CPV cells more favorable than the ubiquitously-used silicon for solar cells. In spite of their high efficiency, gallium arsenide have found limited use in various application thanks to high cost of the GaAs or Ge wafer used.
In an approach to supply low cost CPV cells, we've developed a technology to grow epitaxial semiconductor thin films on low-cost flexible epi-ready metal tapes which will replace the expensive wafers. The template layers on the epi-ready metal tapes are grown via a roll-to-roll process using inoic beam Assisted Deposition. Metal organic chemical vapor deposition is employed to epitaxially grow CPV cells structure on 'single-crystalline-like' germanium film on epi-ready metal foils.
These epitaxial GaAs films exhibit excellent crystalline alignment, excellent crystalline alignment with high carrier mobility, and optoelectronic properties. These grown thin films were processed via etching, photo-lithographyand get in touch with deposition to fabricate single-junction (1J) gallium arsenide photovoltaic cell devices. The fabricated photovoltaic cell underwent a process of cap layer removal (passivation) and anti-reflection coating. Efficiency greater than 6% with circuit voltage (VOC) of 566mV, fill factor (FF) of 68%, short current density (JSC) of 17.4mA/cm2 was obtained.
Steps were taken to enhance the standard of contact by improving the standard of Ge template and incorporating an intrinsic layer with p-i-n photovoltaic cell structures. a tool efficiency of 11.5 you bored with VOC of 566mV, FF of 68%, JSC of 17.4mA/cm2 was obtained at 1 Sun on improved Ge template, using CVD germanium rather than sputtered germanium used before. Solar cells fabricated with the improved p-i-n structure showed a tool efficiency of 13.2% at 1 sun with VOC of 650 mV, JSC of 28 mA cm−2, and FF of 72 %. These thin film GaAs photovoltaics, with further improvement in quality, can potentially cause light-weight, inexpensive and scalable photovoltaic cell manufacturing.