Ultrapurification of Silicon for Photovoltaic Applications

Abstract

Abstract. The recent explosive growth of Photovoltaics and the relative avidity for silicon of the predominant solar cell technology have resulted in a dramatic change of the polysilicon industry structure. While in the past the polysilicon was manufactured almost exclusively for the semiconductor industry, now more than half of the market is devoted to the solar industry. The different alternative routes to purify silicon for photovoltaic applications are presented in the paper, analysing their advantages and drawbacks. Emphasis is made on the CENTESIL initiative, a new private-public partnership venture promoting a pilot plant that is in an advanced state of construction. The goal is to allow the photovoltaic companies worldwide to count with an independent research centre to help them to establish their own polysilicon plant.

Thermal Shields for Heat Loss Reduction in Siemens-Type CVD Reactors

“…for layer deposition in superconducting devices or for the epitaxial growth of silicon layers. 10,11 Several proposals have recently been made for polysilicon production, [12][13][14] but to our knowledge quantitative analysis supported by experimental data has not been provided in any of them.…”

“…One way to overcome these drawbacks would be to use a thermal shield made of purified silicon. 12 Not only will it avoid contamination, but one can also collect the silicon deposited on the shields, adding it to the silicon produced in a batch.…”

Understanding and improving the chemical vapor deposition process for solar grade silicon production

“…To obtain SoG Si, there was a vast effort on research and development (R&D) after the oil crisis in the 1970s, with many alternative paths being explored. Most of them did not reach an industrial scale, and PV kept relying on the traditional chemical route, the so called Siemens process [Ceccaroli and Pizzini, 2012], [del Cañizo et al, 2010], [Herring and Hunt, 1990]. Nowadays, the vast majority of SoG Si is still produced by the Siemens process -more than the 90%-; as this class of process is currently the only one available from technology suppliers and engineering firms [Bye and Ceccaroli, 2014].…”