Growth of high-quality AlN and AlN/GaN/AlN heterostructure on sapphire substrate

Metalorganic chemical vapor deposition (MOCVD) growth of AlN on sapphire substrates was investigated, with the aim of device quality AlN/GaN/AlN double heterostructures. Growth temperature as high as 1300 degrees C was required to obtain AlN epitaxial layers with sharp X-ray diffraction peaks. By growing AlN at the high growth temperature, residual stress at the heterointerface was effectively reduced. The AlN epitaxial lasers with smooth surfaces were grown using a low V/III ratio together with the high growth temperature. AlN/GaN/AlN double heterostructures with appropriate layer thicknesses for DH lasers and flat heterointerfaces were grown on sapphire substrates.