Pulsed Laser Deposition of Thin Films for Lasers and Quasi-Phase Matched Devices

The work performed under this award focused on the growth by Pulsed Laser Deposition, at the University of Southampton, of thin films of Ti doped sapphire, intended for lasing waveguide applications, and their subsequent characterization at AFRL in terms of surface profilometry and Ti concentration. A range of films was analyzed, principally by SIMS, to evaluate Ti concentration, and to attempt to correlate the results with 1 alternative measurements such as EDX, XPS and PIXE obtained by other labs, and 2 the PLD growth parameters used. One of the major and on going problems is the precision with which dopants such as Ti can be measured when concentrations are in the sub 0.1 level. Techniques that are readily available, such as EDX energy dispersive x ray analysis, have problems with accuracy, and can have detection limits that are far from equate for this problem. There is the additional problem that lines can as shown below spectrum recorded at Southampton, which further limits the possibility of quantitative determination. This was the basis for the work that was undertaken between Southampton and AFRL, namely the quantitative assessment of Ti dopant concentrations in a range of PLD grown samples. Complications, to be further discussed below, for such low concentrations also revolve around 1 matrix considerations the underlying quality of the sapphire host, 2 the unknown concentration of Ti in the original PLD target. 3 availability of a comparison sample with known Ti concentration for normalization of SIMS analysis.