Article ID | Journal | Published Year | Pages | File Type |
---|---|---|---|---|
6535709 | Solar Energy Materials and Solar Cells | 2014 | 7 Pages |
Abstract
With the final goal of integrating III-V materials on silicon substrates for tandem solar cells, the influence of the metal-organic vapor phase epitaxy (MOVPE) environment on the minority carrier properties of silicon wafers has been evaluated. These properties will essentially determine the photovoltaic performance of the bottom cell in a III-V-on-Si tandem solar cell. A comparison of the base minority carrier lifetimes obtained for different thermal processes carried out in a MOVPE reactor on Czochralski silicon wafers has been carried out. An important degradation of minority carrier lifetime during the surface preparation (i.e. H2 anneal) has been observed. Three different mechanisms have been proposed for explaining this behavior: (1) the introduction of extrinsic impurities coming from the reactor; (2) the activation of intrinsic lifetime killing impurities coming from the wafer itself; and finally, (3) the formation of crystal defects, which eventually become recombination centers. The effect of the emitter formation by phosphorus diffusion has also been evaluated. In this sense, it has been reported that lifetime can be recovered during the emitter formation either by the effect of the P on extracting impurities, or by the role of the atomic hydrogen on passivating the defects.
Related Topics
Physical Sciences and Engineering
Chemical Engineering
Catalysis
Authors
Elisa GarcÃa-Tabarés, Ignacio Rey-Stolle,