MASS-SPECTROMETRIC STUDY OF THE PYROLYSIS REACTIONS IN THE MOVPE OF GA2SE3 BY IN-SITU GAS SAMPLING

An investigation of the thermal decomposition reactions of trimethylga llium (Me(3)Ga) and hydrogen selenide (H2Se) using hydrogen as a carri er gas involved in the growth of Ga2Se3 (and/or GaSe) was undertaken, using a simple mass spectrometric sampling system on a conventional at mospheric pressure metalorganic vapour phase epitaxy reactor, MOVPE, r eactor. The mass fragments corresponding to the unreacted precursor sp ecies as well as stable volatile hydrocarbon products were monitored u sing a quadrupole mass spectrometer as the temperature of the suscepto r, the VI/III ratio and the precursor mole fractions were varied. The only gas phase hydrocarbon product detected was methane. Possible mech anisms for the reaction of Me(3)Ga with hydrogen selenide have been in vestigated theoretically and the implications of these results for the growth of Ga2Se3 (and/or GaSe) epilayers are discussed.