Interface-related exciton-energy blueshift in GaN/AlxGa1-xN zinc-blende and wurtzite single quantum wells

The role of nonabrupt interfaces on the confined exciton energy blueshift i n zinc-blende and wurtzite GaN/AlxGa1-xN single quantum wells (QWs) is inve stigated. The theoretical calculations are performed taking into account a range of values for the electron and heavy-hole effective masses in both ph ases, which is compatible to those that have been measured and/or estimated from first principles calculations. The interface related ground state exc iton energy blueshift is shown to depend strongly on the nonabrupt interfac es widths in the case of thin QWs ((similar to)(<)80 Angstrom), being a lit tle higher in zinc-blende than in similar wurtzite QWs. For a 50 Angstrom ( 80 Angstrom) wide GaN/Al0.3Ga0.7N single QW whose nonabrupt interfaces have a thickness of 10 Angstrom, the nonabrupt interface related ground state e xciton energy blueshift is 26 meV (5 meV) and 19 meV (3 meV) in the zinc-bl ende and wurtzite phases, respectively. It is shown the impossibility of th e sharp interface picture to describe exciton related emission properties o f GaN/AlxGa1-xN single QWs with a precision better than 10 mev. [S0163-1829 (99)02532-1].