Effect of AlN interlayer on the impurity incorporation of GaN film grown on sputtered AlN

We investigated the influence of AIN interlayer with varied VIM ratio on the impurity incorporation of GaN films grown on sputtered AIN layer by metal organic chemical vapor deposition (MOCVD). It is found that the V/III ratio of AIN interlayer significantly influences on the growth mode and leads different impurity distribution and electron properties. In the case of AIN interlayer with an optimized V/III ratio, incorporation of oxygen impurity in GaN epitaxial films is suppressed. Leading to the GaN film shows a high sheet resistivity. However, at a lower V/III ratio, an unexpected three-dimensional growth mode plays dominant role. While at a higher V/Ill ratio, the GaN polarity would invert to N-polar. Both these two situations would deteriorate the electrical properties of GaN film. (C) 2017 Published by Elsevier B.V.