Optical, Electrical, and Scintillation Properties of Al-doped ZnO Films Synthesized by Laser-assisted CVD

We synthesized Al-doped ZnO (Al:ZnO) thin films by laser-assisted CVD and investigated their optical, electrical, and scintillation properties.The films exhibited a wurtzite-type ZnO structure with a strong (002) orientation.The averaged in-line transmittance in the visible wavelength region (380-780 nm) decreased from 90.4 to 49.0% as the Al concentration (C Al ) increased from 0 to 35.8 at.%.The sheet resistance reached a minimum of 2.47 /sq at C Al = 7.9 at.%.The Al:ZnO films with C Al = 2.7-7.9 at.% exhibited UV emission at 375 nm originating from free excitons, whereas films with higher C Al showed no obvious emission.The average decay time constant of the Al:ZnO film with C Al = 7.9 at.% was 2.10 0.08 ns under 5.5 MeV -ray excitation.Moderate Al addition improved electrical conductivity and photoluminescence intensity, whereas excessive Al led to the deterioration of these properties owing to the formation of an amorphous phase.