The present work focuses on the effect of bandgap engineering on the photo sensing application of Lanthanum (La3+) doped ZnO thin films deposited on glass substrates using spray pyrolysis technique. The × ray diffraction of films showed the polycrystalline nature having hexagonal wurtzite structure with preferred orientation of (1 0 1) plane. The Zn0.94La0.06O films exhibited highest crystallinity of ∼23.7 nm. The strain and dislocation density decreased till 6 at% La3+ doping and increased for higher doping concentrations. The change in the fibrous structure to grain like morphology with the addition La was noticed at higher doping concentration. The composition analysis confirmed the presence of elements and its state of Zn, O and La in the deposited films. The Zn0.94La0.06O film showed visible region transparency above 90 % and band gap of ∼3.27 eV. The near band edge emission (NBE) and deep level emission (DLE) were noticed in all the films. The defects decreased with the La addition due to the proper incorporation of La3+ in ZnO lattice. The pure ZnO films showed the maximum oxygen related defects (∼58.8 %) and Zn0.94La0.06O films showed lesser defects (∼13 %). The electron carrier concentration ∼8.48 × 1016 cm−3, mobility ∼49.6 cm2/V and the resistivity ∼2.52 × 102 Ω cm were noticed in Zn0.94La0.06O films. The photocurrent of Zn1-xLaxO increased till x = 6 at% under the ultraviolet light illumination because of the incident photon energy was higher than the band gap of the film. The Zn0.94La0.06O films showed faster response time and maximum photocurrent at 380 nm. Hence the Zn0.94La0.06O films may be employed in the development of possible optoelectronic devices.
All Science Journal Classification (ASJC) codes
- Electronic, Optical and Magnetic Materials
- Atomic and Molecular Physics, and Optics
- Electrical and Electronic Engineering