REMOVAL OF METALLIC HYDRIDES FROM GASEOUS WASTES OF AN LP-MOVPE (LOW-PRESSURE METALLOORGANIC VAPOR-PRESSURE EPITAXY) REACTOR FOR THE GROWTH OF (IN, GA) (AS, P) COMPOUNDS

We have realized a new system for treating gaseous wastes from a metallorganic vapour phase epitaxy (MOVPE) reactor used for the low pressure epitaxial growth of intrinsic and doped semiconducting crystals in the InGaAsP family. The system is based on a series of 5 successive phases of destruction: dilution, combustion pyrolysis, condensation and filtering. The design minimizes the cost remarkably and optimizes the incineration of toxic gases. After the combustion of 138 m3 of H-2 and the incineration of 276 L of phosphine, we observe that the reaction chamber does not show any corrosion nor any deposit of chemical products, which are daily eliminated together with the water produced during the combustion. For the maximum phosphine concentration that has been used (7340 ppm), no phosphine concentration has been detected in the output with a detecting system having a sensitivity of 0.001 ppm. For the total fluxes entering the reaction chamber (10-25 L/min), the transit time (1s) of gas molecules does not limit the efficiency of conversion of toxic gases. This is important if one wishes to adapt this system to a MOVPE production reaction using a higher flux of phosphine.