Lattice and energy band engineering in AlInGaN/GaN heterostructures

We report on structural, optical, and electrical properties of AlxInyGa1-x- yNGaN heterostructures grown on sapphire and 6H-SiC substrates. Our results demonstrate that incorporation of In reduces the lattice mismatch, Delta a , between AlInGaN and GaN, and that an In to Al ratio of close to 1:5 resul ts in nearly strain-free heterostructures. The observed reduction in band g ap, Delta E-g, determined from photoluminescence measurements, is more than 1.5 times higher than estimated from the linear dependencies of Delta a an d Delta E-g on the In molar fraction. The incorporation of In and resulting changes in the built-in strain in AlInGaN/GaN heterostructures strongly af fect the transport properties of the two-dimensional electron gas at the he terointerface. The obtained results demonstrate the potential of strain ene rgy band engineering for GaN-based electronic applications. (C) 2000 Americ an Institute of Physics. [S0003-6951(00)03909-7].