Structure and property of directionally grown SiGe multicrystals with microscopic compositional distribution

Mullticrystalline SiGe with microscopic compositional distributions is an attractive material for a new high efficiency solar cell because it has a possibility to absorb the near infrared light, which is transparent to Si. In this study, structural property and absorption coefficient was investigated for mc-SiGe and those were compared with mc-Si. Columnar structure for mc-SiGe was obtained using directional growth method. It was found that the preferential crystallographic orientation of mc-SiGe is {110} plane, which is different from mc-Si. By measuring the absorption coefficient, we demonstrated that the introduction of microscopic compositional distribution in mc-SiGe is an effective way to increase absorption coefficient in longer wavelength. Mc-SiGe is therefore concluded to be promising for enabling the realization of low-cost and highly efficient solar cells.