Direct Growth of GaN on Al2O3(0001) by Two-Flow Metalorganic Vapor Phase Epitaxy.

We have investigated a method for obtaining GaN films with smooth surface using two-flow metalorganic vapor phase epitaxy, in which one main flow carries a reactant gas parallel to the substrate, and the other subflow carries an in active gas perpendicular to the substrate for the purpose of changing the direction of the reactant gas flow. It is most important to place the substrate toward the subflow gas within the accuracy of 0.05°. This arrangement contributes to the long stay of NH3 on the substrate, which means higher NH3 decomposition rate and leads to good surface morphology