Indication of room temperature ferromagnetism in highly transparent and conductive Ga-doped SnO2 thin films

• Gallium doped tin oxide thin films
• Optical band gap increases with the oxygen partial pressure.
• Photoluminescence emission band at 372 nm
• Room temperature ferromagnetism

Gallium-doped tin oxide films have been prepared on glass substrates by using the pulsed laser deposition method at different oxygen partial pressures. Structural, electrical, optical, and magnetic properties of the films have been investigated as a function of oxygen partial pressure. The X-ray diffraction patterns show that the all films have rutile structure of pure SnO2 with a strong (200) preferred orientation. The average transmittance in the visible region was observed between 82 and 86% with a sharp fundamental absorption edge. The optical band gap is found to increase from 4 to 4.18 eV with the increasing oxygen partial pressure. The best opto-electrical properties are shown by the film deposited at oxygen partial pressure of 7.99 Pa. Magnetic measurements reveal that samples exhibit room temperature ferromagnetism (RTFM), which should be an intrinsic characteristic. The origin of RTFM is attributed to the carrier (electron) mediated, in which the degree of magnetic coupling between the doped ions will depend on the availability of the free electrons.