Large bandgap bowing of InxGa1-xN films and growth of blue/green InxGa1-xN/GaN MQWs on highly tensile strained GaN/Si(111) hetero structures

InxGa1-xN films and InxGa1-xN/GaN multiple quantum wells (MQWs) were grown on highly tensile strained GaN/Si(111) structure by MOCVD. Due to the large difference of lattice constant and thermal expansion coefficient between GaN and Si, GaN growth on Si(111) substrate usually leads to an initially high dislocation density and cracks. We demonstrate the low dislocation density and crack-free GaN films grown on Si(111) substrate introducing an AlN/GaN strain compensation layer and SixNy dislocation masking layer. The Raman shift of E2 phonon peak of GaN films on Si(111) substrate indicate the strong tensile stress (0.474 GPa). The InxGa1-xN bandgap energy depended on In-composition, which can be fitted by a larger bowing parameter of b=4.5 eV in Ga-rich region (x<0.25). Also, crack-free InxGa1-xN/GaN MQWs with blue and green emissions were demonstrated. (copyright 2006 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)