| Popis: |
Thin-film AlGaAs-GaAs double-heterostructure concentrator cells were fabricated which exhibit total-area conversion efficiencies as high as 23.5% AM0 at 100 suns, 25 degrees C. This is one of the best space concentrators measured to date at NASA and is designed for a thin-film cell without a prismatic coverglass. This solar cell structure consists of a GaAs/AlGaAs film less than 5 mu m thick mounted to a glass cover/superstrate, with coplanar back-side contacts. The coverglass is not prismatic. The CLEFT process, a method for mechanically separating epitaxial. layers from their substrate, is used to process these cells into thin films. The advantages of single-crystal GaAs are thereby retained, while reducing weight and cutting cost by allowing for substrate reuse. Thin-film cells also have better thermal management capabilities and can be stacked for use in tandem structures. Cell fabrication and performance are described, and directions for further improvements are identified. > |
