The composition of phosphorus and arsenic vapor in view of thermal processing of III-V wafers

In-situ Raman scattering results on vapor of phosphorus and arsenic at temperatures up to 1400 K are presented. The ratio of partial pressures of the dimer and the tetramer is proportional to the ratio of the corresponding Raman intensities. With respect to the quantitative comparison of the experimental Raman data with thermodynamical calculation (ChernSage) the Raman activities were determined by first principles calculations on these molecules. In particular, we comment on the presence of trimer components in these gases as conjectured in thermodynamics.