Growth of GaN on 4-inch Si substrate with a thin AlGaN/AlN intermediate layer

We have investigated the crystal growth of GaN on 4-inch Si substrate with a thin AlGaN/AlN intermediate layer. Both the density of pits and the full-width at half-maximum (FWHM) value of the X-ray rocking curve (XRC, ω mode, GaN (0004)) decreased with increasing thickness of the AlGaN/AlN intermediate layer. We have also investigated the quality of GaN and wafer bowing as a function of the GaN layer thickness. With the increase of GaN layer thickness, the FWHM of XRC decreased and the bowing distance of the wafer increases. While the narrowest FWHM value (GaN (0004)) was obtained to be 700 arcsec from 1.5-μm-thick GaN, the bowing distance of the wafer was 100 μm and some cracks were observed at the edge of the wafer. We conclude that the optimum thickness of GaN on 4-inch Si substrate is 1 μm. The FWHM for the near band edge emission of GaN peaking at 364.5 nm was obtained to be 43.9 meV from 1-μm-thick GaN.