A single junction gallium arsenide (GaAs) solar cell on silicon (Si) substrate with energy conversion efficiency of 11.88% under the AM1.5 G spectrum at 1 sun intensity without an anti-reflection coating (ARC) has been developed.
This development was enabled by utilizing an intermediate, thin arsenic-doped germanium (As-doped Ge) buffer layer. The thin epitaxial Ge layer (< 2 µm) grown on the Si substrate created a virtual Ge-on-Si (Ge/ Si) substrate for subsequent growth of the GaAs solar cell, providing low threading dislocation density (TDD) of < 5 × 106 cm−2.
The energy conversion efficiency could be further improved to 16% upon optimizing the ARC and metal coverage. Hence, a manufacturable III-V photovoltaic on a large-area Si substrate has become possible.
Wang, Y., Ren, Z., Thway, M., Lee, K., Yoon, S.F., Peters, I.M., Buonassisi, T., Fizgerald, E.A., Tan, C.S. and Lee, K.H., 2017. Fabrication and characterization of single junction GaAs solar cells on Si with As-doped Ge buffer. Solar Energy Materials and Solar Cells, 172, pp.140-144.
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