Structural and optical characterization of nonpolar GaN/AlN quantum wells

We have grown nonpolar GaN/AlN multiple quantum wells by plasma-assisted molecular-beam epitaxy on R-plane sapphire substrates. X-ray diffraction and selected-area diffraction data show that the III-nitride epilayers are oriented in the {[}11 (2) over bar0] direction with the {[}0001] axis lying in the plane of the substrate. The 18-A GaN quantum wells exhibit luminescence at 326 nm, which is in agreement with the transition energy calculated using a flat-band model; that is, without the presence of a built-in electric field. (C) 2003 American Institute of Physics.