Modeling analysis of AlN and AlGaN HVPE

Comprehensive model of AlN and AlGaN HVPE is developed. The model combines detailed description of the transport processes and quasi-thermodynamic model of surface kinetics at the Al/Ga metal surfaces and AlN/AlGaN crystal surfaces. It is shown with the model that HCl dominantly converts into trichloride AlCl(3) in the Al source but into monochloride GaCl in the Ga source. Then, AlN grows from AlCl(3) under essentially non-equilibrium conditions while GaN - from GaCl under near-equilibrium conditions. The revealed differences between the AlN and GaN growth features explain many experimentally observed phenomena, including a sharp saturated behavior of the AlN growth rate in variation of the precursors flow rates and a strong effect of carrier H(2) on the AlGaN composition. Generally, the model predicts a high sensitivity of the AlGaN composition to variation of the species flow rates due to their effect on the Ga incorporation. (C) 2009 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim