An Efficient Optimized RTP Process to Minimize Light Induced Degradation Phenomenon and Their Effect on Surface Roughness in p-Type Cz-Si Wafers
| Autor: | Kouhlane, Y., Bouhafs, D., Khelifati, N., Mezghiche, S., Guenda, A., Hetatache, W., Derkaoui, F. |
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| Jazyk: | angličtina |
| Rok vydání: | 2018 |
| Předmět: | |
| DOI: | 10.4229/35theupvsec20182018-2av.1.34 |
| Popis: | 35th European Photovoltaic Solar Energy Conference and Exhibition; 539-542 In this study, the carrier lifetime variation of p-type boron-doped Czochralski silicon (Cz-Si) wafers was investigated after a direct rapid thermal processing (RTP). Two wafers were passivated by silicon nitride (SiNx:H) layers, deposited by plasma-enhanced chemical vapor deposition (PECVD) system on both surfaces. Then the wafers were subjected to an RTP cycle at a peak temperature of 620°C. The first wafer was protected (PW) from the direct radiative heating of the RTP furnace by placing the wafer between two as-cut Cz-Si shield wafers during the heat treatment. The second wafer was not protected (NPW) and followed the same RTP cycle. The carrier lifetime eff was measured by the quasi-steady-state photoconductance (QSSPC) technique, before and after an illumination step at 0.5 suns for 5 hours duration. The immediate results of measured lifetime RTP after the RTP process have shown regeneration in the lifetime for the two wafers, but the PW wafer exhibited an important enhancement in RTP compared to the NPW wafer. The QSSPC measurements after 5h of illumination have indicated a good stabilization of lifetime (d) and a weak degradation effect was observed for the PW wafer compared to their initial lifetime. Additionally, to improve the correlation between the RTP heat radiation stress and carrier lifetime behavior, a simulation of the thermal stress and temperature profile by the finite element COMSOL software on the wafers surface at RTP peak temperature of 620°C was performed. The results confirm the reduction of the thermal stress and less heat loss for the protected wafer. Finally, the proposed method can lead to improving the lifetime of wafers by an RTP process with minimum energy costs. |
| Databáze: | OpenAIRE |
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