Growth of crack-free high-quality GaN on Si(111) using a low-temperature AIN interlayer: Observation of tilted domain structures in the AIN interlayer

We report on the growth of crack-free high-quality GaN layers on Si(111) using a low-temperature AIN interlayer (LT-AIN IL) between GaN epilayers by ultrahigh vacuum chemical vapor deposition. The use of a thin LT-AlN IL resulted in the complete elimination of cracks and significant improvements in structural and optical properties of the GaN layer. The GaN epilayer containing the LT-AlN IL exhibited a strong band-edge emission with the line width of 26.5 meV at room-temperature. Additional distinct domains with a tilt angle of ±0.9° in the LT-AlN IL, found by synchrotron X-ray diffraction, are believed to play a key role in the effective relaxation of thermal stress and the reduction of threading dislocations.