Improved crystal quality of GaN film with the in-plane lattice-matched In_0.17Al_0.83N interlayer grown on sapphire substrate using pulsed metal—organic chemical vapor deposition

We report on an improvement in the crystal quality of GaN film with an In_0.17Al_0.83N interlayer grown by pulsed metal—organic chemical vapor deposition, which is in-plane lattice-matched to GaN films. The indium composition of about 17% and the reductions of both screw and edge threading dislocations (TDs) in GaN film with the InAlN interlayer are estimated by high resolution X-ray diffraction. Transmission electron microscopy (TEM) measurements are employed to understand the mechanism of reduction in TD density. Raman and photoluminescence measurements indicate that the InAlN interlayer can improve the crystal quality of GaN film, and verify that there is no additional residual stress induced into the GaN film with InAlN interlayer. Atomic force microscopy measurement shows that the InAlN interlayer brings in a smooth surface morphology of GaN film. All the results show that the insertion of the InAlN interlayer is a convenient method to achieve excellent crystal quality in GaN epitaxy.