Emploi de lasers dans la technologie des photopiles

Dans cet article on passe en revue les différentes applications des lasers de puissance continus ou impulsionnels dans la technologie des cellules solaires à base de silicium. On considère tout d'abord les différents modèles développés pour calculer les effets de ces flux lumineux intenses sur le silicium ; puis, on analyse les possibilités d'emploi de ces dispositifs pour préparer des films autosupportants ou des couches sur substrat. Finalement, trois méthodes de réalisation de la jonction sont décrites : activation de dopants diffusés, implantation ionique conventionnelle ou simplifiée et dépôt de films en surface

Electron spin and cyclotron resonance of laser annealed silicon

EPR and cyclotron resonance investigations have been performed on laser annealed Si wafers, leading to the identification of the [V + O i]- complex in virgin Si and to a donor signal quenching in P-implanted Si

Hydrogen ion passivation of multicrystalline silicon solar cells

It has been recognized that hydrogen can be chosen to passivate the defects present in polycrystalline materials. Technically, the best approach is to use hydrogen ion implantation at low energy (0.5 to 5 keV) by means of a Kaufman or similar type ion source in order to reduce the processing time. For our multiple beam ion source, we have determined the effective concentration profile of the introduced hydrogen, the modification of the optical properties of the implanted wafers and the conditions under which two multicrystalline materials (POLYX and SILSO) will give the greatest improvement in solar cell performance

Recrystallization of silicon by pulsed lasers

Calculation of the evolution of temperature during pulsed laser annealing has been performed. The results are presented in directly useful figures for the two kinds of laser generally used (YAG, Ruby). The results are compared to various experimental measurements performed by RBS. If the crystallographic quality is quite good, TSC and DLTS measurements have shown that electrically active defects are still present after laser annealing

ELECTRON SPIN RESONANCE INVESTIGATION OF THE EFFECTS OF THE H2+ IMPLANTATION AND DIFFUSION ONE THE LASER INDUCED DEFECTS IN VIRGIN SILICON

Electron paramagnetic resonance of the defects induced by laser annealing at high power density (2 J/cm-2) has been investigated in virgin FZ semi-insulating Silicon. A further H2+ implantation and diffusion is inactive on the signal observed at gx = 2.0055 ± 0.0005. This is consistent with the attribution of X to the dangling bonds, created by the mechanical stresses during the thermal shock, as they are not passivated by molecular hydrogen

Polyx multicrystalline silicon solar cells processed by PF+ 5 unanalysed ion implantation and rapid thermal annealing

Rapid thermal annealing of damage induced by implantation in silicon can be a cost effective technology for the processing of terrestrial solar cells as compared to classical furnace or pulsed laser annealing. Unfortunately, drawbacks as poor bulk lifetime or low open-circuit-voltage occur as well. We have attempted to overcome these limitations for POLYX multicrystalline cast silicon grown by CGE (France) by keeping the annealing temperature of the phosphorus doped layer as high as 800 °C (to ensure a good crystalline quality and a high dopant activation) while being less than 900 °C (to minimize the effect of degradation of the base properties). The purpose of the present work is to investigate the I-V characteristics of the cells and to compare to those obtained with classical furnace annealing or with classical diffusion process