Publicação
Co and (Co,Mo) doping effects on the properties of highly reduced TiO2 anatase thin films
| Resumo: | This work reports on the structural, optical, electrical and magnetic properties of Co:TiO2 and (Co,Mo):TiO2 anatase thin films grown onto (0001) sapphire substrates by Pulsed Laser Deposition in highly reducing conditions and at a low temperature of 350 _C. Undoped TiO2_d as well as doped films with nominal compositions of Ti0.95Co0.05O2_d, Ti0.94Co0.05Mo0.01O2_d, and Ti0.92Co0.05Mo0.03O2_d were studied. They all show similar microstructures, with smooth surfaces and RMS roughness values less than 0.5 nm. The optical band gap energies of the doped films are red shifted with respect to that deduced for the undoped TiO2_d. The correlation between the band gaps and the Urbach energies of the films is discussed. All samples show semiconductor behavior with n-type conduction. The Co:TiO2 sample is ferromagnetic with a saturation magnetization of 1.3 mB/Co, a high electrical conductivity of 123 S cm_1 and a carrier density of 1.88 _ 1021 cm_3 at room temperature. The ferromagnetic order of the Co:TiO2 system is suppressed when carriers are added by codoping with Mo. |
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| Autores principais: | Silvestre, António Jorge |
| Outros Autores: | Rout, S.; Dalui, S.; Pereira, Laura; Viana, Ana; Conde, Olinda |
| Assunto: | Pulsed laser deposition Co-doped TiO2_d thin films Mo codoping Oxide based DMS |
| Ano: | 2017 |
| País: | Portugal |
| Tipo de documento: | artigo |
| Tipo de acesso: | acesso restrito |
| Instituição associada: | Instituto Politécnico de Lisboa |
| Idioma: | inglês |
| Origem: | Repositório Científico do Instituto Politécnico de Lisboa |
| Resumo: | This work reports on the structural, optical, electrical and magnetic properties of Co:TiO2 and (Co,Mo):TiO2 anatase thin films grown onto (0001) sapphire substrates by Pulsed Laser Deposition in highly reducing conditions and at a low temperature of 350 _C. Undoped TiO2_d as well as doped films with nominal compositions of Ti0.95Co0.05O2_d, Ti0.94Co0.05Mo0.01O2_d, and Ti0.92Co0.05Mo0.03O2_d were studied. They all show similar microstructures, with smooth surfaces and RMS roughness values less than 0.5 nm. The optical band gap energies of the doped films are red shifted with respect to that deduced for the undoped TiO2_d. The correlation between the band gaps and the Urbach energies of the films is discussed. All samples show semiconductor behavior with n-type conduction. The Co:TiO2 sample is ferromagnetic with a saturation magnetization of 1.3 mB/Co, a high electrical conductivity of 123 S cm_1 and a carrier density of 1.88 _ 1021 cm_3 at room temperature. The ferromagnetic order of the Co:TiO2 system is suppressed when carriers are added by codoping with Mo. |
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