A novel technique for in-situ mass spectrometry of elemental Hg in an atmospheric pressure MOVPE reactor is presented for the first time. A quadrupole mass spectrometer was used together with a differentially pumped, heated by-pass line to probe gas samples from the reactor chamber, allowing fast response times and negligible Hg condensation. Preliminary results on Hg detection by the present apparatus are reported for the case of typical Hg-H2 gas mixtures probed from the reactor. The expected contributions relative to Hg+ and Hg++ were found in the mass spectra, but in several cases the additional formation of mercury hydride molecular ions, HgH+, was observed, for which two different mechanisms are suggested. A signal intensity calibration study of the spectrometer is presented for the Hg-H2 gas mixtures; as a result of this study, the actual value of the p(Hg)/p(H2) partial pressure ratio in the gas phase can be measured within a 10-15% error and a calibration equation is given. The present technique should have the potential to study Hg vapour conditions during the MOVPE growth of II-VI compounds.
In situ mass spectrometry of mercury vapour during MOVPE growth of II-VI compounds
LOVERGINE, Nicola;
1991-01-01
Abstract
A novel technique for in-situ mass spectrometry of elemental Hg in an atmospheric pressure MOVPE reactor is presented for the first time. A quadrupole mass spectrometer was used together with a differentially pumped, heated by-pass line to probe gas samples from the reactor chamber, allowing fast response times and negligible Hg condensation. Preliminary results on Hg detection by the present apparatus are reported for the case of typical Hg-H2 gas mixtures probed from the reactor. The expected contributions relative to Hg+ and Hg++ were found in the mass spectra, but in several cases the additional formation of mercury hydride molecular ions, HgH+, was observed, for which two different mechanisms are suggested. A signal intensity calibration study of the spectrometer is presented for the Hg-H2 gas mixtures; as a result of this study, the actual value of the p(Hg)/p(H2) partial pressure ratio in the gas phase can be measured within a 10-15% error and a calibration equation is given. The present technique should have the potential to study Hg vapour conditions during the MOVPE growth of II-VI compounds.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
