GaN buffer layer growth by MOCVD using a thermodynamic non-equilibrium model

Abstract

In this work, a gallium nitride (GaN) buffer layer was grown on a sapphire substrate (α-Al 2O 3) in a horizontal reactor by low pressure metal-organic chemical vapor deposition (LP-MOCVD). Trimethylgallium (TMGa) and ammonia (NH 3) were precursors of gallium and nitrogen, respectively, and hydrogen (H 2) was used as carrier gas. TMGa and NH 3 fluxes were kept constant, with flow rates of 3.36 μmole/min and 0.05 standard liter/min, respectively. The fluence of hydrogen was also kept constant with the flux rate of 4.5 standard liter/min. GaN was deposited at 550 °C and 100 mbar. According to the X-ray diffraction spectra, a buffer layer was formed with a wurtzite structure, which is the stable phase. The thermodynamic affinities were estimated as A 1 = 175.9 kJ/mole and A 2 = 62.88 kJ/mole.