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Improvement of charge carrier lifetime in heat exchange method multicrystalline silicon wafers by extended phosphorous gettering process
| Content Provider | Semantic Scholar |
|---|---|
| Author | Bouhafs, Djoudi Boumaour, Messaoud Moussi, A. Khelifati, Nabil |
| Copyright Year | 2011 |
| Abstract | External phosphorous diffusion gettering were applied using homogenous and extended schemes on multicrystalline silicon (Mc-Si) wafers obtained from solar grade (SOG) silicon feedstock by the heat exchange method (HEM) growth technique. X-ray fluorescence (XRF) characterization shows the presence of transition metals like Chromium (Cr), manganese (Mn) and iron (Fe) in the analyzed as-cut Mc-Si substrates with a predominance of Mn and Fe elements. Before and after gettering process, we have observed that the Cr atoms concentration drop from 4.10 15 at.cm -3 in the as-cut Mc-Si samples to 2.5 10 15 at.cm -3 with homogeneous gettering and to 3.10 14 at.cm -3 in the wafer undergoes extended gettering. The quasi-steady-state photo conductance (QSSPC) technique is used to characterize the minority charge carrier's lifetime τn before and after gettering process. It was found that the response of Mc-Si wafers is better (form point of view of lifetime improvement) to the extended process but in some regions it is less effective and the homogenous process give the best amelioration due probably to the spatial distribution of crystalline defects and metallic precipitates densities. With τn initial values before gettering in the range of 2.5-8 µsec, we have measured lifetime values in the range of 15 to 37 µsec with extended process and from 10 to 30 µsec with the homogenous one which ensure cell efficiencies in the range of 15 to 16%. Resume- Les techniques d'effet Getter externe par diffusion du phosphore ont ete appliquees en utilisant des procedes homogenes et etendus sur les plaquettes de silicium multi cristallin 'mc-Si' obtenues a partir des matieres premieres de silicium de qualite solaire (SOG) par la methode de l'echangeur de chaleur (HEM) en technique de croissance. La caracterisation par la fluorescence X (XRF) revele la presence de metaux de transition comme le chrome 'Cr', le manganese 'Mn' et le fer 'Fe' dans les substrats analyses brutes 'mc-Si' avec une predominance des elements 'Mn' et 'Fe'. Avant et apres le procede Getter, nous avons observe que la baisse de la concentration des atomes Cr se fasse a partir de 4×10 15 at.cm -3 dans les echantillons brute 'mc-Si', les echantillons a 2,5×10 15 at.cm -3 avec l'effet Getter homogene et a 3×10 14 at.cm -3 dans la plaquette |
| File Format | PDF HTM / HTML |
| Alternate Webpage(s) | https://www.cder.dz/vlib/revue/pdf/v014_n4_texte_9.pdf |
| Language | English |
| Access Restriction | Open |
| Content Type | Text |
| Resource Type | Article |
