Effect of Al-doping on optical and electrical properties of spray pyrolytic nano-crystalline CdO thin films

• Published in: Current Applied Physics Vol. 10; no. 3; pp. 790 - 796
• Main Authors: Khan, M.K.R., Rahman, M. Azizar, Shahjahan, M., Rahman, M. Mozibur, Hakim, M.A., Saha, Dilip Kumar, Khan, Jasim Uddin
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 01.05.2010; Elsevier BV; 한국물리학회
• Subjects: CdO; Direct band gap; Semiconductor; Spray pyrolysis; 물리학; Direct band gap; Semiconductor; Spray pyrolysis; CdO
• ISSN: 1567-1739; 1878-1675
• DOI: 10.1016/j.cap.2009.09.016

CdO and Al-doped CdO nano-crystalline thin films have been prepared on glass at 300 °C substrate temperature by spray pyrolysis. The films are highly crystalline with grain size (18–32 nm) and found to be cubic structure with lattice constant averaged to 0.46877 nm. Al-doping increased the optical transmission of the film substantially. Direct band gap energy of CdO is 2.49 eV which decreased with increasing Al-doping. The refractive index and dielectric constant varies with photon energy and concentration of Al as well. The conductivity of un-doped CdO film shows metallic behavior at lower temperature region. This behavior dies out completely with doping of Al and exhibits semiconducting behavior for whole measured temperature range. Un-doped and Al-doped CdO is an n-type semiconductor having carrier concentration is of the order of ∼10 21 cm −3, confirmed by Hall voltage and thermo-power measurements.