Effects of metal doping on photoinduced hydrophilicity of SnO2 thin films

Bulletin of materials science

Rajeeb Brahma²  Debarun Dhar Purkayastha²  M Ghanashyam Krishna²  V Madhurima¹ 

[1] Department of Physics, Central University of Tamil Nadu, Thiruvarur 610004, India$$Department of Physics, Central University of Tamil Nadu, Thiruvarur 610004, IndiaDepartment of Physics, Central University of Tamil Nadu, Thiruvarur 610004, India$$;School of Physics, University of Hyderabad, Hyderabad 500046, India$$School of Physics, University of Hyderabad, Hyderabad 500046, IndiaSchool of Physics, University of Hyderabad, Hyderabad 500046, India$$

关键词: Bandgap;    hydrophilicity;    doping;    wettability.;   

DOI  :  

学科分类：材料工程

来源: Indian Academy of Sciences

【 摘 要 】

The influence of metal dopants (Mn²⁺, Al³⁺ and Cu²⁺) on the wetting properties of SnO₂ thin films deposited by thermal evaporation is reported. The undoped and doped SnO₂ films crystallize into the orthorhombic structure upon annealing at 200°C for 110 h. It is shown that wettability behaviour, before and after ultraviolet (UV) irradiation, is dependent on the ionic radius of the dopant. The contact angle of un-irradiated samples increases with increase in ionic radius of the dopant and also in comparison with the undoped sample. It is 54° for pure SnO₂ and increases to 77.5°, 92.3° and 95.9° for the Al³⁺, Mn²⁺ and Cu²⁺ doped samples, respectively. After UV irradiation, the value is 5.4° for the undoped sample. This increases to 21.2° for Al doping reaching a minimum of 6.4° for the Mn-doped sample increasing thereafter to 63.3° for the Cu-doped sample. It is observed that pre-irradiation contact angle behaviour can be correlated with the change in roughness of the films with increasing ionic radius. In contrast, photoinduced hydrophilicity of the films correlates with their optical bandgap. The contact angle is lowest for the lowest bandgap material, i.e., Mn-doped SnO₂, with a bandgap of 2.48 eV. Thus, the band structure of SnO₂ that can be controlled by dopant ionic radius can in turn be employed to manipulate the wettability of these surfaces.

【 授权许可】

Unknown