0510208 - ÚCHP 2020 RIV IT eng C - Conference Paper (international conference)
Bumba, Jakub - Dřínek, Vladislav - Fajgar, Radek - Kaštánek, František - Šolcová, Olga
Recycling of Photovoltaic Cells and other Si, Ge Elecronic Waste.
Proceedings Sardinia 2019. Padova: CISA Publisher, 2019, č. článku 082..
[International Waste Management and Landfill Symposium /17./. Cagliari (IT), 30.09.2019-04.10.2019]
R&D Projects: GA TA ČR(CZ) TN01000048
Institutional support: RVO:67985858
Keywords : electronic waste recycling * silicon * germanium
OECD category: Chemical process engineering

New technology for electronic waste recycling to produce ultrapure silicon, germanium or CVD precursors was thoroughly studied, designed and verified. The three-step-process is based on low-temperature synthesis of magnesium silicide (Mg2Si) and/or germanide (Mg2Ge) directly from end-of-life photovoltaic cells and waste magnesium chips in the case of magnesium silicide and from broken germanium optical lenses and magnesium chips in the case of magnesium germanide preparation. The prepared products were characterised by X-Ray Diffraction (XRD), Scanning Electron Microscopy (SEM) with Energy Dispersive X-Ray Spectroscopy (EDX) and Raman spectroscopy, which confirmed high conversion to desired products, its good crystallinity and also homogeneity. Prepared samples were then hydrolysed by phosphoric acid solution to produce silicon and/or germanium hydrides. Their presence was confirmed by Fourier Transform Infrared Spectroscopy (FTIR) and Gas Chromatography–Mass Spectroscopy (GC-MS). In the next step, it was also tested that silicon and also germanium hydrides are relatively instable to the point that they can be easily decomposed into ultrapure elements Si, Ge and hydrogen. Additionally, it is possible to use them as desirable precursors for the preparation of thin silicon and germanium layers or for the synthesis of metal silicides and germanides by Chemical Vapour Deposition (CVD) methods. The thin semiconductive layers are commonly used in microelectronic industry, while metal silicides and germanides could find potential use in the field of catalysis, thermoelectricity and electronics. The only by-product of the whole process, magnesium phosphate, can be used as a fertilizer.
Permanent Link: http://hdl.handle.net/11104/0300740