Structural, Optical, and Luminescent Properties of ZnO:Ga and ZnO:In Ceramics

Zinc oxide optical ceramics were prepared by the hot uniaxial pressing technique. Nominally undoped and gallium- and indium-doped ceramics were studied. Undoped ceramics with a thickness of 0.5 mm had a total transmittance of about 65% in the visible range and exhibited mainly deep level luminescence at 600 nm. Doping of the ceramics resulted in the appearance of free charge carriers, suppression of the defect emission band, and enhancement of the excitonic luminescence intensity. The typical concentration of donor centers in doped ceramics was on the order of 10
¹⁹
cm
^-1
. Admixture of the dopants also decreased the average grain size of the ceramics and, in the case of indium-doped ceramics, affected their morphology. With respect to the excitonic emission intensity, the optimal concentration of dopants was 0.028 at% of Ga
³⁺
and 0.045 at% of In
³⁺
. The maximum intensity of excitonic luminescence in indium-doped ceramics was about 1.5 times higher than that in gallium-doped ones. Luminescence decay curves of the ceramics with suppressed defect emission had a main decay time constant of 0.7 ns.