Engineering Quartz Sand for Next Generation Solar Crucibles

Most solar cells in the world today are made of thin silicon wafers (Si). The efficiency of the solar cells depends on the number of impurities and defects in the Si wafer are kept at low as possible. Therefore, both the Si which the Si-mono crystal is made out of, and the quartz glass crucible must be very pure. Impurities and defects from the quartz glass can end up destroying the efficiency of the solar cell. The quartz glass crucible must also withstand many hours of use at high temperatures. The quartz glass crucible is made of some of the world's cleanest natural quartz deposits. The Quartz Corp produces high purity quartz to be applied in solar crucibles. In the project, The Quartz Corp, together with SINTEF and NTNU, will try to understand how to make quartz sand even more suitable for quartz glass crucibles. To understand this, one must understand the fundamental characteristics of quartz before and after melting, and for this you need to develop advanced characterization methods and tools. So far in the project, the characterization method toolbox required to measure fundamental properties of quartz sand has been developed.The spectroscopic techniques have been proved and established as the suitable quantitative methods for analysis of the fundamental properties of quartz sand. A melting furnace setup for melting quartz sand under controlled conditions has been built, and instrumentation for measuring the viscosity of quartz glass has been developed.The reproducibility of the results has been checked to ensure that the setup is stable and can be used to investigate quartz glass produced from the quartz sand with modified properties.

Improved fundemenatal knowledge of a significant process has led to product improvements and anticipated market share gains. Additionally new 'in-application' knowledge has helped us gain reputation among our customers.

The underlying idea of this innovation project is to develop an engineered quartz sand for next generation solar cell quartz glass crucibles. This will be achieved by the establishment and implementation of an optimised purification process for quartz sand at The Quartz Corp (TQC) production facilities in Drag, Norway. The purification process will be tailored to robustly remove impurities more efficiency than today's process and at the same time stabilize the surface of the quartz sand particles. TQC has reached a point where empirical experience is not enough to optimize their purification process, and implementation of new and optimised purification process for quartz sand are not possible without research. To develop an engineered quartz sand a crucial first step will be to achieve knowledge of how the fundamental properties of the quartz depend upon different process parameters, and how these properties again influence the melting process of the quartz glass. Establishment of a characterization toolbox for how different fundamental properties can be measured will be a key. The effect of processing steps will be mapped and characterised. The development of a melting process with the possibility to alter melting properties needs to be developed. This knowledge will further be used to understand how the quartz sand quality affect the properties of solar and semiconductor CZ crucibles before and after use. Simulation tools needs to be developed in order to predict how the glass properties are affected by the quartz sand properties. The innovation will form the basis for TQC to take part in the market growth. TQC will prepare for realization by clarifying interfaces with existing production processes, requirements specification and master plans. The innovation will be a key element for TQC to be the number one supplier in high purity quartz sand.