DEPOSITION OF BCN FILMS BY LASER-ABLATION

Thin BCN films were deposited on monocrystalline silicon substrates by laser ablation at 510 nm using CuBr vapor laser. The target materials were synthesized from melamine and BCl3 at 600 and 950 degrees C, and the disks for laser irradiation were prepared by pressing the powders without binder. The focused laser beam scanned the targets with a spe ed of 4 mu m/s. The element analysis by Auger electron spectroscopy (A ES) showed that the layers were composed of B, C, and N with peaks at 177, 266, and 373 eV, respectively. A decrease of nitrogen content in the films compared to both starting materials was observed and the rat ios of the main elements in the deposits were B : C : N = 3 : 9 : 2 an d 6 : 2 : 1. Pulsed CuBr vapor laser irradiation probably caused parti al destruction of the target material, accompanied by release of nitro gen-containing gas species. The formation of such species (N-2, NH3, ( CN)(2)) was observed by quadrupole mass spectrometry during the deposi tion process. Fourier-transform infrared spectroscopy (FTIR) was used to derive structural information. The absorption bands at 1557, 1539, 1457, and 1436 cm(-1) in IR spectrum of the films deposited from start ing material synthesized at 600 degrees C were attributed to the stret ching vibration of the s-triazine ring. Therefore IR spectrum indicate d that in the obtained layer the six-member (C3N3) rings remained unde composed. The additional bands in the spectrum originated from the bri dges between s-triazine rings, composing the layer. The IR spectrum of the films deposited from starting material synthesized at 950 degrees C showed quite different pattern. The s-triazine rings were entirely decomposed above 620 degrees C and the deposit was mixture of boron ni tride and carbide (bands at 1404 and 1108 cm(-1)). X-ray photoelectron spectroscopy (XPS) indicated that the atoms of all elements composing the films were in a wide variety of atomic arrangements and N-C, N-B and B-C bonds were established in the deposits. Electron diffraction ( ED) showed that the films deposited from the starting material synthes ized at 600 degrees C had a layered graphite-like structure.