Determination of defect density of state distribution of amorphous silicon solar cells by temperature derivative capacitance-frequency measurement
| Autor: | Miro Zeman, Guangtao Yang, S. Dobrovolskiy, R.A.C.M.M. van Swaaij |
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| Rok vydání: | 2014 |
| Předmět: | |
| Zdroj: | Journal of Applied Physics. 115:034512 |
| ISSN: | 1089-7550 0021-8979 |
| DOI: | 10.1063/1.4862308 |
| Popis: | In this contribution, we demonstrate the application temperature dependent capacitance-frequency measurements (C-f) to n-i-p hydrogenated amorphous silicon (a-Si:H) solar cells that are forward-biased. By using a forward bias, the C-f measurement can detect the density of defect states in a particular energy range of the interface region. For this contribution, we have carried out this measurement method on n-i-p a-Si:H solar cells of which the intrinsic layer has been exposed to a H2-plasma before p-type layer deposition. After this treatment, the open-circuit voltage and fill factor increased significantly, as well as the blue response of the solar cells as is concluded from external quantum efficiency. For single junction, n-i-p a-Si:H solar cells initial efficiency increased from 6.34% to 8.41%. This performance enhancement is believed to be mainly due to a reduction of the defect density in the i-p interface region after the H2-plasma treatment. These results are confirmed by the C-f measurements. After H2-plasma treatment, the defect density in the intrinsic layer near the i-p interface region is lower and peaks at an energy level deeper in the band gap. These C-f measurements therefore enable us to monitor changes in the defect density in the interface region as a result of a hydrogen plasma. The lower defect density at the i-p interface as detected by the C-f measurements is supported by dark current-voltage measurements, which indicate a lower carrier recombination rate. |
| Databáze: | OpenAIRE |
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