Enhanced absorption in ultrathin Si by NiSi2 nanoparticles. Issue 1 (1st January 2013)

• Record Type: Journal Article
• Authors: Sachan, R.; Wu, Y.; Rack, P. D.; Kalyanaraman, R.; Pennycook, S. J.; Dyck, O.; Garcia, H.; Duscher, G.; Gonzalez, C.
• Is Part Of: Nanomaterials and energy. Volume 2:Issue 1(2013)
• Page Start: 11
• Page End: 19
• Publication Date: 2013-01-01
• Subjects: modeling; -- photovoltaics; -- nanoparticles; -- electron energy-loss spectroscopy; Nanostructured materials -- Periodicals; Nanostructures -- Periodicals; 620.115
• DOI: 10.1680/nme.12.00020
• Languages: English
• ISSNs: 2045-9831

Abstract

Abstract : Various forms of Si including amorphous Si (a-Si) are important photovoltaic (PV) materials. However, in order to improve the cost-to-performance aspects of Si solar cells, such as by enabling ultrathin (<500 nm) Si solar technology, new strategies are required to improve optical absorption within Si, which is a relatively poor absorber of light in the visible solar spectrum. In this study, the authors demonstrate a potential approach to enhance optical absorption in ultrathin a-Si films by embedding nickel di-silicide (NiSi2) nanoparticles (NPs). The Ni silicide NPs were engineered inside 50 nm thick a-Si by thermal annealing of co-deposited Ni and Si thin films on Si and quartz substrates. A quantitative electron energy-loss spectroscopy analysis was used to accurately determine the composition of silicide NPs. From broadband absorption optical studies, integrated optical absorption was found to increase by ∼85% in the visible solar range (350-750 nm) and by ∼150% in the infrared range (750-3000 nm) for the NiSi2 NP incorporated amorphous Si films. Optical modeling captured the absorption behavior of NP embedded a-Si thin films, thus suggesting an efficient route to design new photo-absorber NPs for future Si based PV devices. Various forms of Si including amorphous Si (a-Si) are important photovoltaic (PV) materials. However, in order to improve the cost-to-performance aspects of Si solar cells, such as by enabling ultrathin (<500 nm) Si solar technology, new strategies are required to improve optical absorption within Si, which is a relatively poor absorber of light in the visible solar spectrum. In this study, the authors demonstrate a potential approach to enhance optical absorption in ultrathin a-Si films by embedding nickel di-silicide (NiSi2) nanoparticles (NPs). The Ni silicide NPs were engineered inside 50 nm thick a-Si by thermal annealing of co-deposited Ni and Si thin films on Si and quartz substrates. A quantitative electron energy-loss spectroscopy analysis was used to accurately determine the composition of silicide NPs. From broadband absorption optical studies, integrated optical absorption was found to increase by ~85% in the visible solar range (350-750 nm) and by ~150% in the infrared range (750-3000 nm) for the NiSi2 NP incorporated amorphous Si films. Optical modeling captured the absorption behavior of NP embedded a-Si thin films, thus suggesting an efficient route to design new photo-absorber NPs for future Si based PV devices.