Simulation analysis on impurity distribution in mc-Si grown by directional solidification for solar cell applications

Abstract

We carried out global transient simulation of impurity distribution in multi-crystalline silicon grown by directional solidification using appropriate software. Non-metallic impurities such as carbon, nitrogen and oxygen originate from the furnace parts and each impurity atom was segregated into the mc-Si ingot based on their solubility in the crystal. During the solidification process the temperature distribution causes melt fluctuation in the Si melt, which is controlled by applying an external body force that leads to a uniform distribution of impurity atoms. Here the uniform distribution of impurity atoms was obtained by rotating the crucible at 10 rpm and the investigations were also carried out without crucible rotation and with a crucible rotation rate of 3 rpm. In this paper we have analyzed the segregation of non-metallic impurity atoms and chemical reactions between the impurity atoms, wherein three types of simulations were carried out and their results analyzed.

Effect of high frequency vibrations on PV silicon purification

“…13. In all these cases (Gr v ranging from 500 to 10000), the flow direction at the center of the melt is inverted in the (90°,180°) range between the values 1 and 2 depending on Gr v and given by (11). These limit values 1 and 2 , where the flow is the weakest, correspond to peaks in the , curves (maximum impurity level).…”

“…The main objective of these control techniques is to enhance the level of mixing in the melt, in the vicinity of the growth interface, in order to achieve silicon ingots containing less impurities. Impurities segregation during directional solidification processes has also been investigated in different papers taking into account the rejection of solute at the solid-liquid front and its transport by diffusion and natural convection [11][12][13][14][15][16][17]. In the present work, we propose to use high-frequency vibrations of the crucible to control the flow and therefore the heat and mass transfer in the melt, with the objective to reduce the rate of impurities in silicon ingots grown by the horizontal Bridgman technique.…”

Analysis of the Effect of a Vertical Magnetic Field on Melt Convection and Oxygen Transport During Directional Solidification of Multi-Crystalline Silicon by Numerical Simulation

“…is volume force in the melt when no magnetic field is applied [1,28]. The density in the silicon melt [29,30] is ρ = 3194 − 0.3701T.…”