GaN on Si substrate with AlGaN/AlN intermediate layer

A single crystal GaN thin film was successfully frown on a Si (111) substra te by means of atmospheric pressure metalorganic chemical vapor deposition. Though there is a large difference in thermal expansion coefficients betwe en GaN and Si, an intermediate layer consisting of AlN and AlGaN improved t he quality of GaN on Si and reduced meltback etching during growth. Pits an d cracks were not observed on the substrate and a mirror-like surface was o btained. The full-width at half maximum (FWHM) of the double-crystal X-ray rocking curve for GaN(0004) was 600 arcsec. Photoluminescence measurement a t room temperature for a Si-doped film revealed a sharp band-edge emission with a FWHM of 62.5 meV, which is the narrowest value reported to date.