Publications by authors named "Eric Colegrove"
A general problem for semiconductor applications is that very slow deposition on expensive single-crystal substrates yields high crystalline quality with excellent electro-optical properties, but at prohibitive costs and throughput for many applications. In contrast, rapid deposition on inexpensive substrates or nanocrystalline films yields low costs, but comparatively inferior crystallinity, carrier transport, and recombination. Here, we present methods to deposit single-crystal material at rates 2-3 orders of magnitude faster than state-of-the-art epitaxy with low-cost methods without compromising crystalline or electro-optical quality.
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- Thin film materials for photovoltaics, like CdTe and CIGS, promise lower costs and better performance compared to microcrystalline silicon, but managing electron and hole concentrations in these materials has been a long-standing challenge.
- Ionic bonding in these films leads to difficult-to-control defect chemistries, complicating the enhancement of charge carrier concentrations.
- Research shows that doping and annealing processes can significantly increase hole density in CdTe films, potentially boosting solar cell efficiency to 25% and paving the way for cheaper solar energy compared to traditional sources.
Using two-photon tomography, carrier lifetimes are mapped in polycrystalline CdTe photovoltaic devices. These 3D maps probe subsurface carrier dynamics that are inaccessible with traditional optical techniques. They reveal that CdCl treatment of CdTe solar cells suppresses nonradiative recombination and enhances carrier lifetimes throughout the film with substantial improvements particularly near subsurface grain boundaries and the critical buried p-n junction.
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