Formation of microcones accompanied with ripple patterns in laser-activated plasma CVD of sp ³-bonded BN films

Scanning electron microscopic (SEM) observations revealed that individual and independent microcones of sp ³-bonded boron nitride grown by laser-activated plasma chemical vapor deposition were accompanied by ripple patterns spreading around them in the dimension of micrometers or sub-micrometers. The ripples were expanding equidistantly from each other and diminishing as they depart from a cone. The origin of the ripples was attributed to the interference of a direct laser cast on the plane surface and that reflected from the side of a cone; this model was satisfactorily in agreement with the SEM measurement, in which the side surface of a cone was mapped onto the plane surface surrounding the cone in the mathematical meaning of "bijection." This micro-optical effect due to the wave nature of laser was considered to indicate and support the photochemically activated growth reactions in this process.