CVD Growth and Characterization of SixGe1−x−ySny Alloys for High Efficiency Multi-Junction Solar Cells

Silicon-germanium-tin films were grown by an Epsilon® RPCVD single wafer CVD deposition system to be used as an intermediate cell in high efficiency multi-junction solar cells. Material and optical characterization of the samples are performed using transmission electron microscopy, X-ray diffraction, Rutherford backscattering, Raman spectroscopy, photoluminescence, and eillpsometry techniques. Thicknesses, absorption coefficients, refractive indexes, direct and indirect bandgap transitions were measured and compared for different Sn and Si composition samples. The results show that incorporation of Si in GeSn lattice lowers the lattice size and increases the energy bandgap simultaneously.