UV cathodoluminescence of Gd3+ doped and Gd3+-Pr3+ co-doped YAlO3 epitaxial thin films

Thin films of YAlO3: Gd3+ and YAlO3: Gd3+-Pr3+ were prepared on LaAlO3 (001) single crystal substrates by pulsed laser deposition (PLD). Both films were grown epitaxially and their surfaces were uniformly smooth. Under UV excitation at 216 nm, YAlO3: Gd3+ film did not show any intense photoluminescence (PL); on the other hand, YAlO3: Gd3+-Pr3+ film showed intense Gd3+ PL at 314 nm through Pr3+ 4f-5d absorption. Under electron irradiation with acceleration of 2.00 kV, both films showed UV cathodo luminescence (CL) from Gd3+ ions. In contrast to PL, the CL intensity of the YAlO3: Gd3+ film was four times greater than that of the YAlO3: Gd3+-Pr3+ film. The PL excitation spectrum of YAlO3: Gd3+ in vacuum UV region revealed the presence of an intense excitation band at 155 nm assignable to YAlO3 host absorption. This observation implied that the energy of accelerated electrons was absorbed by the host and then transferred to Gd3+. Pr3+ co-doping was found to weaken the Gd3+ emission in CL because the excitation energy absorbed by the host was transferred to not only Gd3+ but also Pr3+ accompanying visible emission and nonradiative transition in Pr3+. (C) 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim