Mass-spectrometric study of the pyrolysis reactions in the MOVPE of Ga2Se3 by in-situ gas sampling

A study of the mechanism of the reaction of trimethylgallium with hydrogen selenide

“…on the quartz reactor chamber tube liner in front of and at the rear of the susceptor, on the outside of the GaMe 3 inlet nozzle. 3 The inside surface of the sampling tube becomes similarly coated during the sampling process as became evident on examination after completing the experiment. The white/buff coloured material that deposits on the walls is removable using simple methods (aqua regia).…”

“…The basic layout of the sampling system has been described previously. 3 The differentially pumped sampling system was designed to minimise the time that the sampled gases are subjected to gas phase interactions en route to the ionisation chamber of the mass spectrometer. We have considered the possibility that surface catalysed reactions in the sampling tube may have a signi®cant effect on the interpretation of our results due to the large surface/volume ratio (#5) of the sampling tube.…”

“…1,2 The MOCVD growth of Ga 2 Se 3 has been carried out using trimethylgallium (GaMe 3 ) with hydrogen selenide (H 2 Se). 3 Although Ga 2 Se 3 with adequate structural properties could be obtained, 4±6 a severe pre-deposition gas phase reaction occurs with these reagents, compromising the compositional uniformity and surface morphology of the epilayers. More recent attempts to improve Ga 2 Se 3 materials quality have resulted from the use of alternative organoselenium reagents 7,8 and this has been shown to enhance the structural quality of the Ga 2 Se 3 ®lms.…”

“…The work described here was undertaken in an effort to understand the pre-deposition gas phase reactions involved in the growth of Ga 2 Se 3 using GaMe 3 and H 2 Se and to obtain, if possible, kinetic data which could be incorporated in a model of the pre-deposition reaction. Mass spectrometry has been used extensively to study reaction chemistry in MOCVD 3,8,15 although little of the work has led directly to an improvement in the understanding of the relevant reaction kinetics due to the complex nature of the processes involved. In this work mass spectrometry was chosen to study gas phase reactions since it has been used successfully in the past in elucidating the reaction kinetics of the triethylindium/arsine system, 16±17 a precursor combination which undergoes a similiar pre-deposition reaction on mixing.…”

Conformal Coating by High Pressure Chemical Deposition for Patterned Microwires of II–VI Semiconductors

“…A further increase of the ratio (>2.5) leads to columnar growth in the (111) direction, with a greater relative intensity of the (111) diffraction peak (Figure 3c). Elemental Se formation at even higher ratios (>5) is not observed, due to the high temperature needed for decomposition of H 2 Se in H 2 31. For ZnS deposition, the more stable sulfur‐carbon bonds of the (CH 3 ) 2 S molecule result in a smaller Reaction 2 rate constant, requiring a higher VI/II ratio (≈10).…”