Modelling and simulation of oxygen transport during AlN crystal growth by the PVT method

Abstract

The oxygen impurity exists mainly in the form of Al2O during the AlN crystal growth by the PVT method. In this paper, 2D incompressible flow and mass transport models are developed by the FEM method and by taking into account the effects of three-phase (Al/N/Al2O) Stefan flow, buoyancy and vapor diffusion during the PVT AlN crystal growth process. The effects of the growth conditions, viz. the temperature and atmospheric pressure, on the Al2O transport in a 2-in. AlN crystal growth chamber are investigated by a series of numerical simulations using the developed models. The simulation results show that Al2O transport is strongly affected by temperature and atmospheric pressure. A high temperature is unfavourable for AlN crystal growth but is beneficial for the removal of oxygen from the powder source. An increase in the atmospheric pressure can decrease the Al2O partial pressure in the growth chamber and therefore reduce the oxygen content in the growing AlN crystal.