Ichimiya Masayoshi, Horii Taku, Hirai Takeshi, Sawada Yuji, Minamiguchi Masaru, Ohno Nobuhito, Ashida Masaaki, Itoh Tadashi
CREST, Japan Science and Technology Agency, Japan. Graduate School of Engineering Science, Osaka University, 1-3 Machikaneyama-cho, Toyonaka, Osaka 560-8531, Japan.
J Phys Condens Matter. 2006 Feb 15;18(6):1967-75. doi: 10.1088/0953-8984/18/6/012. Epub 2006 Jan 25.
The dependences of cathodoluminescence (CL) from ZnO:Zn phosphor powder upon local space, accelerating voltage and beam current have been investigated at room temperature. Ultraviolet (UV) luminescence, which is hard to be observed in photoluminescence (PL) at room temperature, has been clearly observed in CL as well as green luminescence. The intensity ratio of the UV luminescence to the green one varies from point to point. From the comparison with PL, the UV luminescence is attributed to the recombination of ZnO free excitons. The UV luminescence is little observed at low accelerating voltage where, similar to the excitation light for PL measurement, the electron beam penetrates into only the surface depletion layer where free excitons are unstable due to the surface electric field. However, the UV luminescence from the depletion layer becomes observable at large beam current because of the suppression of the electric field in the depletion layer caused by injected electrons.
室温下，研究了ZnO:Zn磷光体粉末的阴极发光（CL）与局部空间、加速电压和束流的关系。在CL中清晰观察到了室温下光致发光（PL）中难以观察到的紫外（UV）发光以及绿色发光。紫外发光与绿色发光的强度比因点而异。通过与PL比较，紫外发光归因于ZnO自由激子的复合。在低加速电压下几乎观察不到紫外发光，此时与PL测量的激发光类似，电子束仅穿透表面耗尽层，由于表面电场，自由激子在该层不稳定。然而，由于注入电子对耗尽层电场的抑制，在大束流下耗尽层的紫外发光变得可观察到。
