MODEL FOR IN-SITU ETCHING AND SELECTIVE EPITAXY OF ALXGA1-XAS WITH HCL-GAS BY METALORGANIC VAPOR-PHASE EPITAXY

In-situ etching and selective epitaxy of AlxGa1-xAs by introducing a s mall amount of HCl gas were carried out by low-pressure metalorganic v apor phase epitaxy (MOVPE). A thermodynamic model based on the equilib rium state is presented to explain the etch and growth rates. These re sults show that the reaction between gas phase and surface is in quasi -equilibrium. An increase in material migration length on the surface caused by introducing HCl gas is thought to be the main reason for imp rovement in selective epitaxy.