Actual temperatures of growing surfaces of Ill-nitride-based materials depending on substrates and forced convection conditions in metal organic chemical vapor deposition

摘要

We have investigated the differences in the actual surface temperature of various substrates for the growth of Ill-nitride materials and the influence of this difference in the characteristics of the resulting epitaxial films. From calculations using the finite element method, high-thermal conductivity substrates have significantly higher surface temperature than substrates with low thermal conductivity in typical growth conditions of metal organic chemical vapor deposition. Also, the hydrodynamics of various growth parameters and the chamber condition play a significant role in establishing the actual surface temperature. The thickness of the substrate is found to be another important factor on the temperature of the surface. High resolution x-ray diffraction analysis of AlGaN epitaxial layers grown on bulk A1N substrates and sapphire substrates with different thicknesses supports our theoretical calculations, showing that the Al compositional discrepancy originated from the differences in the surface temperature during growth.