Optical and structural properties of Diamond/GaN films

We report on the successful deposition of continuous boron-doped diamond films on p-GaN substrate in a hot-filament chemical vapor deposition (HFCVD) system. The Raman spectrum observed at 1331 cm− 1 is a distinctive, asymmetric Fano line shape, which shows that the films under the present growth condition are heavily doped. The photoluminescence spectra for GaN (the diamond is taken away from the Diamond/GaN sample) are characterized by significant spectral peak located at 3.358 eV. After annealing at 700 °C, a sharp PL line located at 358 nm (3.468 eV) is then observed. Additionally, the zero phonon line is located at 3.27 eV. However, this line has a blueshift of 0.25 eV in comparison with PL spectra for p-type GaN:Mg. This blueshift, which may be accounted for a by large lattice relaxation is associated with the dissociation of C diffusion into GaN.