The mechanism of ultraviolet (UV) and green emission of ZnOthin filmsdeposited on (001) sapphire substrates by pulsed laser deposition was investigated by using postannealing treatment at various annealing temperatures after deposition.Structural, electrical, and optical properties of ZnOfilms have been also observed. As the postannealing temperature increased, the intensity of UV (380 nm) peak and the carrier concentration were decreased while the intensity of the visible (about 490–530 nm) peak and the resistivity were increased. The role of oxygen in ZnOthin film during the annealing process was important to the change of optical properties. The mechanism of the luminescence suggested that UVluminescence of ZnOthin film was related to the transition from near band edge to valence band, and green luminescence of ZnOthin film was caused by the transition from deep donor level to valence band due to oxygen vacancies. The activation energy derived by using the variation of green emission intensity was 1.19 eV.

Annealing effect on the property of ultraviolet and green emissions of ZnO thin films

This study addresses the material properties of magnetron-sputtered aluminum-doped zinc oxide (ZnO:Al) films and their application as front contacts in silicon thin-film solar cells. Optimized films exhibit high conductivity and transparency, as well as a surface topography with adapted light-scattering properties to induce efficient light trapping in silicon thin-film solar cells. We investigated the influence on the ZnO:Al properties of the amount of alumina in the target as well as the substrate temperature during sputter deposition. The alumina content in the target influences the carrier concentration leading to different conductivity and free carrier absorption in the near infrared. Additionally, a distinct influence on the film growth of the ZnO:Al layer was found. The latter affects the surface topography which develops during wet-chemical etching in diluted hydrochloric acid. Depending on alumina content in the target and heater temperature, three different regimes of etching behavior have been i...

/pdf/the-effect-of-front-zno-al-surface-texture-and-optical-1x1n27941a.pdf

The effect of front ZnO:Al surface texture and optical transparency on efficient light trapping in silicon thin-film solar cells

Violet and UV luminescence emitted from ZnO thin films grown on sapphire by pulsed laser deposition

https://www.repository.cam.ac.uk/bitstream/1810/264501/1/Fu_et_al-2017-Progress_in_Material_Science-VoR.pdf

Tokihiro Nishihara

Papers

Control of preferred orientation for ZnOx films: control of self-texture

Heteroepitaxy of zinc oxide thin films, considering non-epitaxial preferential orientation