Binding energy (eV) By replacing the Si (100) substrate with 4H-SiC (0001), which is a more suitable substrate for GaN with respect to the lattice mismatch, XRD in -2 geometry showed only the GaN (0002) and (0004) peaks together with the substrate peaks. This indicates that growth occurred only in the c-direction (Figure ). The GaN film was deposited at 250  C using a 4 s pulse of 1 and 9 s NH3 plasma pulse. GIXRD of the GaN film grown on SiC showed no peaks, indicating no tilted grains present in the film (Figure ). Pole figures were constructed to investigate the epitaxial relationship between the film and the substrate (Figure and). The GaN (101 ̅ 3) plane was used due to large difference in the psi angle between GaN and SiC, making it possible to distinguish between the GaN and SiC poles. The pole figure showed six poles, representing the hexagonal GaN lattice with its six-fold symmetry (Figure ). The SiC (101 ̅ 2) plane show six poles, representing its hexagonal six-fold symmetry (Figure ). These pole figures show that the hexagonal GaN crystals have grown exactly on top of the SiC crystals, confirming that epitaxial GaN has been grown directly on SiC substrate. The epitaxial relationship between the film and the substrate is GaN(0002) SiC (0004) and GaN (101 ̅ 3)  SiC (101 ̅ 2). It is worth noting that no AlN interlayer was used to aid the growth of GaN on SiC, which is required for CVD of GaN on SiC. This opens up the possibility for deposition of GaN on transistor structures without the need of a buffer layer between SiC and GaN.