We report on the growth and optical characterizations of multicrystalline SiGe (mc-SiGe) with microscopic compositional distribution for solar cell applications. Mc-SiGe was grown by a simple technique based on the casting method. The compositional distribution and solidification structure of mc-SiGe were found to be strongly dependent on the cooling rate, suggesting that they can be controlled by the growth parameters. Spatial variation of the extinction coefficient, corresponding to the microscopic compositional distribution, was revealed by spectroscopic ellipsometry, and macroscopic optical properties were found to be controlled by the microscopic compositional distribution. The advantage of mc-SiGe was further revealed by the increased absorption in the lower energies compared with uniform SiGe with almost the same average composition.
- Microscopic compositional distribution
- Multicrystalline SiGe
- Solar cells