PHOTOINDUCED PHASE INHIBITION DURING GROWTH OF BORON-NITRIDE THIN-FILMS

Boron nitride exists in three polymorphic forms which are thermally stable to decomposition, chemically inert and possess a wide band gap. Deposition of thin films containing various BN phases has been achieved using gas source molecular beam epitaxy in tandem with a 500 W mercury arc lamp. Thermal evaporation of elemental boron from an effusion cell and the decomposition of molecular nitrogen in an electron cyclotron resonance plasma provided the reactive species for film growth at 400 and 500-degrees-C on single-crystal substrates of Si (100). The films contained both amorphous and hexagonal (layered structure) BN without the use of the arc lamp. Films growth with the arc lamp showed a dramatic decrease in the concentration of the hexagonal phase and evidence of an increase in the concentration of the cubic BN.