Structural, electrical and optical properties of SnO2: B transparent semiconducting thin films

Boron (B) is considered as an important impurity in semiconductor physics and optoelectronic devices, especially to produce p-type silicon (p-Si). In this paper, we investigate the effect of Boron doping on the structural, electrical, optical, and photo-sensitivity properties of tin oxide (SnO2) semiconductor thin films. Boron doped tin oxide (SnO2: B) thin films were deposited on glass substrates at Ts=500 ͦC for different atomic concentration of x=[B/Sn] = 0, 0.02, 0.04, 0.08, 0.10, 0.20, 0.30, and 0.50 by spray pyrolysis technique. The results of X-ray diffraction (XRD) analysis show the tetragonal rutile SnO2 structure with orientation along the (211) plane. The films have polycrystalline structure with granular and island-like grains morphology by Field-Emission Electron Microscope (FE-SEM). The SnO2:B films have shown n-type conductivity and decreasing - increasing behavior of electrical resistivity with B-doping for x ≤ 0.04 and x 0.04, respectively. Also, carrier concentrations were obtained in the order of 1018-1020 cm-3. Average optical transmittance of SnO2:B thin films changed in the range of 65% to 87% in the visible region and SnO2:B (x=0.08) sample has highest transmittance. The optical gap of films was obtained in the range of 3.47-3.87 eV. From the photoconductive results, the x=0.50 film has exhibited the most optical sensitivity under light radiation.