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 20] 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.