Objectives
Objective 01
Experimental and numerical study of natural convection effect on impurity segregation and coating stability in a Bridgman method for multicrystalline Si growth (WUT, INES)
Activities - Objective 01
1.1. Growth of multicrystalline silicon for various types of coatings, temperature gradients and growth rates (WUT)
1.2. Characterization of obtained silicon crystals by FTIR to measure the level of contamination (WUT)
1.3. Characterization of obtained silicon crystals by other techniques at CEA-INES (Glow discharge Mass Spectroscopy and Inductively Plasma Mass Spectroscopy) (WUT+INES, one student from Romania to INES, 6 months)
1.4 Numerical simulation of the crystallization processes in order to evaluate the level of convection (WUT)
1.5 Comparison of experimental results with numerical simulations and dissemination of the results (WUT)
Objective 02
Modelling of Si crystal growth process in furnaces with stirring devices (WUT)
Activities - Objective 02
2.1 Two dimensional global modelling of CEA pilot scale furnace, in order to optimize growth conditions and to obtain boundary conditions for 3D simulations
2.2. Build up a 3D model(convection, diffusion, segregation) for CEA pilot scale furnace with a stirring device
2.3. Perform numerical simulations to achieve a complete mapping of the parameter space (temperature gradients, blade speeds and growth rates)
2.4. Build up a 3D model for CEA pilot scale furnace with a multi blade stirring device
2.5 Comparison of experimental results with numerical simulations and dissemination of the results (WUT+INES)
Objective 03
Growth of multicrystalline silicon in laboratory (2 kg ingots) and pilot scale (60 kg ingots) furnaces with a stirring device (INES)
Activities - Objective O3
3.1. Implementation of a single rotating blade on the crucible axis in the laboratory scale furnace
3.2. Analysis of the influence of the stirring induced flow on impurity segregation and Si3N4 coating stability for various blade speeds
3.3. Growth experiments and sample characterization by FTIR to identify secondary phases within silicon matrix. If necessary, improve the cohesion of the coating
3.4. Implementation of a single rotating blade on the crucible axis in the pilot scale furnace
3.5 Silicon growth experiments in pilot scale furnace at various prescribed growth rates (5, 10, 15, 20 cm/h)
3.6 Sample characterizations (GDMS, ICP-MS, minority carrier lifetimes and diffusion lengths)