Dislocation reduction in GaN films through selective island growth of InGaN

Dislocation reduction in GaN films grown on sapphire and silicon substrates was achieved by inserting thin InGaN layers grown in a selective island growth mode after partial passivation of the GaN surface with a submonolayer of silicon nitride. We show that this technique is most effective at reducing the pure edge dislocation density when it is high (i.e., > 10(10) cm(-2)) and less when the density is in the 10(8)-10(9) cm(-2) range. Thus, the structural quality of typically highly dislocated GaN on silicon films could be significantly improved, visible in a reduction of the (0002) full width at half maximum (FWHM) from 1300 arcsec for ordinary GaN on silicon to 800 arcsec for GaN films with silicon nitride/InGaN interlayers. In the case of GaN layers grown on sapphire (dislocation density similar to 10(9) cm(-2)), the method resulted mainly in a reduction of the FWHM of the (10 (1) over bar 2) and (20 (2) over bar 1) diffraction peaks. (C) 2000 American Institute of Physics. [S0003-6951(00)00343-0].