Lifetime Measurements on Attached Epilayers and Detached Epifoils Grown on Reorganised Porous Silicon Showing a Bulk Lifetime Exceeding 100μs
| Autor: | Kris Van Nieuwenhuysen, Ferenc Korsos, Valerie Depauw, Ivan Gordon, Hariharsudan Sivaramakrishnan Radhakrishnan, Jef Poortmans, Maarten Debucquoy, Robert Mertens |
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| Rok vydání: | 2013 |
| Předmět: |
Recombination velocity
PL Photoluminescence Materials science business.industry High cell Substrate (electronics) Porous silicon surface recombination velocity QSSPC epilayer porous silicon Energy(all) μ-PCD Optoelectronics PC1D bulk lifetime Diffusion (business) business Microwave Order of magnitude |
| Zdroj: | Energy Procedia. 38:950-958 |
| ISSN: | 1876-6102 |
| DOI: | 10.1016/j.egypro.2013.07.369 |
| Popis: | This paper discusses on-going efforts towards reliable lifetime measurements on epilayers and the subsequent decoupling of the bulk and surface recombination components, both while it is still attached to the p+ substrate on which it is grown (“attached epilayer”) and after its detachment from the substrate (“detached epifoil”). For the “attached epilayers”, microwave photoconductance decay (^-PCD) and simulation-assisted photoluminescence (sim-PL) were applied together with a variation in the epilayer thickness to evaluate the bulk lifetime (Tbulk) and total effective surface recombination velocity (Stot) of p-type epilayers. By applying linear fits to reciprocal effective lifetime versus reciprocal epilayer thickness data, Stot of all samples were reliably extracted, resulting in Stot of ∼265 cm/s in the absence of porous silicon at the epilayer/substrate interface compared to ∼9220 cm/s when present and ∼775 cm/s when shielded by a thin back surface field. Based on these Stot values, sim-PL was used to estimate Tbulk to be ∼160 |us in the porous silicon area. For the n-type “detached epifoils”, quasi-steady state photoconductance (QSSPC) was used. However, reliable Tbulk could not be extracted, despite the lower Stot because Tbulk was too high. However, a lower limit to Tbulk was estimated to be >138 μs. Such high bulk lifetimes imply bulk diffusion lengths that are an order of magnitude longer than the epilayer thicknesses, potentially leading to high cell efficiencies. |
| Databáze: | OpenAIRE |
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