THE USE OF AZO-COMPOUNDS AS PROBES OF CARBON INCORPORATION OF NOMINALLY UNDOPED METALORGANIC VAPOR-PHASE EPITAXY GROWN GAAS

Secondary ion mass spectroscopy has been used to quantitatively determine the carbon concentration in nominally undoped GaAs grown by metalorganic vapor phase epitaxy from TMG (C-13 99%) and AsH3. Both an increase in the V/III ration and the addition of supplemental gas phase radicals reduced the carbon incorporated from the TMG. Higher V/III ratios are proposed to increase the surface concentration of AsH(x) species. Supplemental gas phase t-butyl radicals, produced from the decomposition of azo-t-butane, are proposed to attack AsH3, also resulting in an increase in the surface concentration of AsH(x) species. Higher surface concentrations of AsH(x) are then proposed to reduce carbon incorporation by enhancing the desorption of carbon-containing species.