Kaltaev K. Influence of the nitrogen-containing reducing media on the volume and surface characteristics of sapphire

A complex investigation of the influence of the nitrogen-containing reducive media on the structural, optical and luminescent properties of sapphire is carried out in this work. A new method of the aluminum nitride crystalline layers obtaining on the sapphire surface is developed. It was determined that an interaction of Al2O3 with the media, a partial pressure of oxygen in which lower than a partial pressure of oxygen over sapphire with stoichiometric composition, containing nitrogen, along with breaking the stoichiometry of sapphire accompanies with the nitrogen dissolving in the oxygen sublattice of anion-defected sapphire with forming of solid solution of Al2O3:N. It was determined that a nitrogen dissolving process accompanies with forming of F+-centres and assembling F2-centres - defects which essentially reduces transparensy of sapphire in the UV region of spectrum, causes yellow colouring of the crystalls and changing their luminescent properties. A new crystalline AlN layers obtaining method by the thermochemical nitridation of sapphire in the reducive media allows to obtain on the sapphire substrates crystalline AlN layers which have thickness from 20 nm to 50 mkm, FWHM 0,3-0,5 ° and a roughness Ra ~5 nm (at initial roughness of the sapphire substrate 2 nm).