An experimental approach for real time mass spectrometric CVD gas phase investigations

Abstract

This is a report on the first setup of a recently developed, extremely sensitive and very fast 3D quadrupole ion trap mass spectrometer inline in a metalorganic vapour phase epitaxy (MOVPE) system. This setup was developed ultimately for the decomposition- and the interaction analysis of various established as well as novel metalorganic sources for MOVPE deposition of III/V semiconductors. To make in-situ gas phase and growth interaction analysis on a new level of sensitivity possible without disturbing the MOVPE growth process itself, an optimized experimental connection of the mass spectrometer to the MOVPE system is required. This work reports on the realization of such an experimental setup and provides first proof of concept for decomposition analysis. In addition, a comparison to previous studies and gas-phase analysis at MOVPE systems will be given in this work.

Thermal decomposition of CuProp2: In-situ analysis of film and powder pyrolysis

“…The sample temperature is measured with a thermocouple soldered to the platinum plate and controlled with an external tubular furnace placed around the quartz tube. Interpretation of the MS spectra of the volatiles was done according to NIST reference spectra, but it should take into account that the fragmentation pattern of the analyte can show temperature dependence in favor of lower molecular weight fragments [30,31]. X-ray diffraction curves (XRD) of powders and films (the latter were peeled off to be measured) were collected using an X-ray beam wavelength of 1.5406 Å (Cu-Kα) from two different diffractometersμ a Siemens diffractometer (model D-5000) from Bruker, operating at a 35-mA current and at a voltage of 45 kV; and a D8 ADVANCE diffractometer from Bruker AXS, with an X-ray beam of Cu-Kα, operating at a 40-kV voltage and with a 40-mA current.…”

Using evolved gas analysis – mass spectrometry to characterize adsorption on a nanoparticle surface

“…† Also, the contribution of fragments m/z ¼ 30 and 42 is larger than expected; the higher amount of small fragments is due to an enhancement of spontaneous dissociation with temperature. [28][29][30] The presence of acetate on the NP and supraparticle surface (Fig. 4) is conrmed although the relative intensities of the m/z peaks cannot be determined due to the overlapping with tetramethylammonium fragments.…”

“…Again, the lower intensity of the fragment m/z ¼ 68 can be attributed to thermally induced dissociation that favors the formation of smaller fragments. [28][29][30] From the EGA-MS curves, we can identify the presence of citraconic anhydride in YF 3 particles thanks to the peaks of the above fragments at 200 and 285 C (Fig. 5a).…”

In Situ Growth Analysis

“…Analysis of the gas composition behind the reactor yields results from a gas composition, which is not representative for the hot zone at the sample due to reactions during cooling. Therefor a gas probe is ingested in vicinity of the sample surface by a capillary [9,10] or, in an early experiment, via a small orifice in the sample susceptor [11]; the latter arrangement yields a short sample path length, so that short-lived reactive species like free radicals are not removed by wall reactions and gas-phase recombination reactions. This provides the most realistic pattern of the growth ambient.…”

“…In a more recent study of tertiarybutylarsine (TBAs, (C 4 H 9 )AsH 2 ) pyrolysis a sensitive ion-trap mass spectrometer was fed by a nozzle in an MOVPE reactor to probe the gas phase in an epitaxial environment and largely avoid fragmentation by ionization [10]. The results given in Fig.…”