Laser processing of BN and AIN films

Abstract

We have formed cubic boron nitride (c-BN) and hexagonal aluminum nitride (h-AlN) using novel pulsed laser processing methods. To synthesize c-BN, the boron target was evaporated by pulsed KrF laser (λ = 248 nm) with simultaneous bombardment with nitrogen ions. On the other hand, epitaxial deposited h-AlN on silicon and sapphire substrates was accomplished by pulsed laser evaporation of AlN target. The films of c-BN were polycrystalline on Si(100) and Si(111) substrates, and high-quality epitaxial h-AlN film was grown on (0001) sapphire with a following in-plane alignment of \( AlN[\overline 1 2 \overline 1 0] ||Al_2 O_3 [0 \overline 1 10] and AlN[10 \overline 1 0] || Al_2 O_3 [\overline 2 110] \). This is equivalent to 30° rotation of the film with respect to the substrate in the basal c-plane. The absorption edge measured by ultraviolet-visible spectroscopy for the epitaxial AIN film was sharp and the band gap was found to be 6.1eV. Details of microstructure-property correlation of these films and possible applications are discussed.