Low energy Auger electron spectroscopy of titanium nitrides for quantitative analysis

The potential of the low energy (20–30 eV) region of the Auger spectrum of titanium nitrides for quantitative analysis has been examined. Nitride films were prepared by nitrogen ion implantation and adsorption at 300 and 900 K and subject to Auger electron analysis in both the low and high energy regions, The nitrogen concentration of implanted films will be uniform over the analysed depth and could be determined by spectrum simulation of the high energy region, a technique described previously. This method permitted an internal calibration of the low energy Auger spectrum against nitrogen composition. The low energy spectrum contains two major features which vary in intensity, and energy, with x, the N/Ti atom ratio: Peak A, present in the pure Ti spectrum and assigned to the Ti(3p)Ti(3d)Ti(3d) transition, has an intensity which decreases linearly with x, whereas peak B, present in the stoichiometric nitride and attributed to the Ti(3p)Ti(3d)N(2p) cross transition, has an intensity which reaches a maximum at x = 0.05. The linear decrease in peak A intensity was ascribed to the linear decrease in the number of unoccupied octahedral holes with x. Occupied intrahole and occupied-unoccupied inter-hole transitions make a contribution to peak B and the latter will pass through a maximum at x = 0.5. The low energy spectrum calibration permitted depth profiles to be determined for adsorbed films at 300 and 900 K. In the latter case both methods gave the same result because rapid diffusion produces a film uniform over the analysed depth. For adsorbed films produced at room temperature the high and low energy results were quite different, reflecting the increased depth resolution of the low energy electrons.