Determination of Bulk Minority-Carrier Lifetime in BaSi_2 Earth-Abundant Absorber Films by Utilizing a Drastic Enhancement of Carrier Lifetime by Post-Growth Annealing

摘要

We have successfully determined the bulk minority-carrier lifetime in BaSi_2 epitaxial films by utilizing a drastic enhancement of lifetime by post-growth annealing at 800℃, which is attributed to strain relaxation. From the film-thickness dependence of lifetime, we reveal that the bulk lifetime is 14μs, which is long enough for thin-film solar cell applications. In addition, the sum of surface and interface recombination velocities is found to be as low as 8.3 cm/s presumably due to the ionic nature of BaSi_2. This confirms that BaSi_2 is promising as an absorption-layer material for earth-abundant thin-film solar cells.