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, $Δa,$ between AlInGaN and GaN, and that an In to Al ratio of close to 1:5 results in nearly strain-free heterostructures. The observed reduction in band gap, $ΔEg,$ determined from photoluminescence measurements, is more than 1.5 times higher than estimated from the linear dependencies of $Δa$ and $ΔEg$ on the In molar fraction. The incorporation of In and resulting changes in the built-in strain in AlInGaN/GaN heterostructures strongly affect the transport properties of the two-dimensional electron gas at the heterointerface. The obtained results demonstrate the potential of strain energy band engineering for GaN-based electronic applications.