Effect of Post - N+ Implantation on the Microstructure of the Interfacial Non - Cubic BN Layers

Plasma source ion implantation has been applied as a post treatment in order to modify the interfacial sp2 bonded layer of the cubic BN (cBN) films. The effect of ion irradiation on the microstructure of the non-cubic BN layer was investigated. From HRTEM observation, the thickness of the BN layer of the representative sample was about 100 nm including 15 nm of initially grown non-cubic layer at the interface between a substrate and the cubic layer. At optimal plasma source implantation conditions, an acceleration voltage of 50 keV and an ion dose of 2×10(16)ions/㎠, the microstructure of the interfacial non-cubic BN layer was changed. It was noticed that the ion irradiation caused the recrystallization of the amorphous phase and trans-formed the small crystallites into another phase. The micro-hardness of the complex consisting of a hard and soft layer increased as a result of phase transformations. This was caused by atomic displacements in the initially grown amorphous and hexagonal layers. The atomic displacements calculated by the TAMIX code were in the range of 0.31~0.52 nm per atom within 70~100 nm in depth.