Description
The project aims to create a more energy-efficient technology to produce polycrystalline rod. Project main task is to create an energy-efficient technology through which polycrystalline rods in the ingot form are produced by pulling from the melt, created with electron beam as the heat source. Rods are produced by an electron beam directed to the heat source. Obtaining experimental polycrystalline rods in small samples as the basis for a possibility to get dislocation free float zone silicon single crystals, and dimensional crystals for an industrial application have not been accomplished yet. It is planned to create such a control method for the industrial manufacture of Latvia. The project will achieve electrical power saving, reaching 1 225 000 kWh/per year and reduction of CO2 emissions 133,5 t/per year. The project will be implemented in cooperation with Institute of Solid State Physics, University of Latvia.
Summary of project results
The aim of the project was to create an alternative technology for the production of polycrystalline silicon rods from a melt with electron beam heating. The design of the electron beam heater has been studied, a new design of a copper bath with water cooling has been developed, in which a thermal unit has been assembled, impurity concentrations have been measured. The impurity concentration was determined by spectroscopy in rods obtained in the project on single crystals, which were extracted from such rods. It is established that the metals from the structural elements of the electron beam heater enter the melt. At the same time, the concentration of impurities in the resulting crystals is smaller than in solar silicon but is worse than required for the growth of single crystals. In this connection, experiments were conducted to create and optimize the shape of the gas-dynamic window for the gas insulation of guns and the process chamber. Two solutions are patented. The documentation for manufacturing of the corresponding devices is developed. The composition of impurities in the obtained samples was studied at the Institute of Solid State Physics of the University of Latvia using low-temperature spectroscopy on single crystals of grown from the described rods.
Summary of bilateral results