STRUCTURE OF EPITAXIAL DELTA-NBN FILMS DEPOSITED BY CATHODE REACTIVE SPUTTERING

The low-temperature (298-673 K) growth and structure of epitaxial delt a-NbN thin films (100-800 Angstrom) deposited by reactive sputtering o n the (100) NaCl cleavage surface have been studied by transmission el ectron microscopy. The films have a parallel epitaxial orientation (10 0)(NaCl)parallel to(100)(NbN) and contain microtwin interlayers in the (111) planes. The microtwin content dependence on the background press ure as well as on deposition rate has been found. It has been conclude d that microtwins form at the initial growth stage as a result of coal escence of islands of different orientations, (100) and (111), like co ndensed fee metal films. The high density of block boundaries and the distortion of coherent growth with small film thicknesses (h approxima te to 100 Angstrom) are attributed to the high activation energy of co alescence and recrystallization processes characteristic of refractory compounds.