Thin film sputtering of gadolinium and chromium-doped yttrium aluminum garnet

In this work, rf magnetron reactive sputtering was used to synthesize yttrium aluminum garnet (YAG) thin films at relatively low temperature and short processing period. A combination of 80W for yttrium target, 130W for aluminum target, and a total pressure of 3 mTorr gas mixtures with 25 sccm argon and 1.4 sccm oxygen flow rate produced a Y3Al5 O12 stoichiometric thin film.; Gadolinium and chromium-doped YAG thin films were synthesized in a combinatorial fashion. The combinatorial thin film sputtering technique rapidly determined the gadolinium and chromium concentration that yielded the optimum luminescence intensity to be ∼5.5 at% for YAG:Gd and ∼0.69 at% YAG:Cr films, respectively. The concentration quenching phenomena were discussed.; A 23 full factorial design of experiments (DOE) was conducted to investigate the effects of substrate temperature, substrate bias, and oxygen flow rate on the luminescence properties and the crystallinity of YAG:Gd and YAG:Cr thin films, respectively. DOE results showed that increasing O2 flow rate decreases both luminescence intensity and film crystallinity, substrate temperature slightly improves luminescence and has a negligible effect on crystallinity, and substrate bias enhances luminescence but decreases crystallinity. The effects of the parameters were thoroughly interpreted by correlating the composition and morphology of the films. Single factor studies for each variable verified the DOE results. The optimum process condition consists if low O 2 flow rate and high substrate bias.; The effect of total pressure of the Ar/O2 gas mixture on CL efficiency and XRD intensity was also investigated.; The PL temperature dependence of YAG:Gd and YAG:Cr thin films were studied in a temperature range of 15-298 K. The thermal quenching phenomena were observed above ∼110K on both YAG:Gd and YAG:Cr films. Activation energies of 24.7 meV and 25.2 meV were estimated for YAG:Gd and YAG:Cr films, respectively. Both activation energies were attributed to electron-phonon coupling.