Selective Boron Elimination from B₂H₆–SiH₄Gas Mixtures for Purifying Si

Abstract

A boron elimination method based on the difference in the pyrolysis temperatures of SiH4 and B2H6 is proposed for purifying metallurgical grade Si feedstock for photovoltaic applications through direct hydrogenation using high-pressure hydrogen plasma. A simple kinetic model is constructed to estimate the proposed boron elimination filter performance. The filter performance is experimentally evaluated. It is confirmed that there is a significant temperature difference between the B2H6 and SiH4 transmission behavior through the filter. However, when SiH4 and B2H6 gases are simultaneously supplied to the filter at the same flow rate of a few standard cubic centimeters per minute, the SiH4 transmission curve is affected by B2H6 and almost overlaps with the B2H6 curve. In contrast, by decreasing the B2H6 flow rate to one thousandth the SiH4 flow rate, B2H6 co-supply has little influence on the SiH4 transmission curve. The type of carrier gas (H2 and He) also affects the transmission curve. With increasing filter temperature, the B elimination effect of the filter becomes greater. The B concentration in Si films prepared by a single elimination process can be reduced to about 1/3000 of the value estimated from the concentration ratio in the unfiltered gas mixture.

Synthesis of Sodalite Zeolite and Adsorption Study of Crystal Violet Dye

“…High values of specific area and SAR contribute to the formation of zeolites, as a result of lesser number of non-reactive phases during synthesis. [80][81][82][83][84][85][86] Adsorption study of dye in sodalite.-The adsorption process of the dye was investigated in five different concentrations (100, 75, 50, 25, 10 and 5 mg/L) and the results (removal percentage of dye) are exhibited in Figures 6A-6F. In Figures 6A, 6B and 6C, we have the initial concentrations of 100, 75 and 50 mg/L of the dye which remained in contact with the zeolitic material (SAR of 1.0 -2.5) throughout the period of 6 to 72 hours.…”