V. Linss

Mechanical properties of thin films in the ternary triangle B-C-N

Abstract We report on thin films in the ternary system B–C–N deposited by reactive magnetron sputtering of targets with different B/C ratio in an Ar/N 2 gas mixture. First, the proportion of nitrogen in the gas was varied from 0 to 100% with the substrate being at floating potential in order to change the incorporated amount of nitrogen in the films. Secondly, at 50% nitrogen in the gas a negative substrate potential was applied for ion bombardment of the growing film. The film composition was measured by elastic recoil detection analysis. The mechanical properties, Youngs modulus and hardness, were determined from nanoindentation measurements. All films were also investigated by Fourier-transformed infrared spectroscopy (FTIR). The mechanical properties show a great variation range in dependence on the film composition (up to a factor of three) and ion bombardment (up to a factor of two), which can be related to the bonding characteristics derived from the FTIR spectra.

Two N2+(B2 u+) populations with different Boltzmann distribution of the rotational levels found in different types of N2/Ar discharges—improved estimation of the neutral gas temperature

We investigated the rotational excitation of the nitrogen molecule ion in a pulsed magnetron sputter discharge (Mg target, pressure 0.1–2.0 Pa) and a 150 Pa dc glow discharge in dependence on various process parameters. For this purpose we used optical emission spectroscopy of the 0–0 band of the first negative system of the (FNS0–0) and calculated the rotational temperature by fitting the spectra. Often, the best fit could be achieved assuming two populations of the molecules having two different rotational temperatures. These temperatures and their contributions to the spectrum of the FNS0–0 show a significant dependence on the process parameters. The lower temperature is in the range of 370–800 K and is believed to be equal to the translational temperature of the neutral gas. The higher temperature is in the order of 1500–3000 K and its origin is most probably the excitation of the state by heavy particle impact connected with rotational excitation.

Analysis of the biaxial strain state of Al-doped c-BN films using diffraction experiments with synchrotron radiation

Abstract Thin films of cubic-boron nitride with a small amount of aluminum were produced by rf magnetron sputtering of a h-BN target and an additional Al ring-shaped electrode. Then the strain state of the biaxially stressed films was measured using synchrotron X-ray diffraction and the lattice spacing that unstressed films would have was calculated for different amounts of aluminum. This unstressed lattice spacing gets larger with increasing Al-amount. There is much evidence that the aluminum atoms are substitutionally incorporated at boron sites. This article provides an insight into the method of determining the unstressed lattice spacing using a slightly changed sin 2 Ψ method.