title: New Insights on the Burstein-Moss Shift and Band Gap Narrowing in Indium-Doped Zinc Oxide Thin Films.
abstract: The Burstein-Moss shift and band gap narrowing of sputtered indium-doped zinc oxide (IZO) thin films are investigated as a function of carrier concentrations. The optical band gap shifts below the carrier concentration of 5.61 × 1019 cm-3 are well-described by the Burstein-Moss model. For carrier concentrations higher than 8.71 × 1019 cm-3 the shift decreases, indicating that band gap narrowing mechanisms are increasingly significant and are competing with the Burstein-Moss effect. The incorporation of In causes the resistivity to decrease three orders of magnitude. As the mean-free path of carriers is less than the crystallite size, the resistivity is probably affected by ionized impurities as well as defect scattering mechanisms, but not grain boundary scattering. The c lattice constant as well as film stress is observed to increase in stages with increasing carrier concentration. The asymmetric XPS Zn 2p3/2 peak in the film with the highest carrier concentration of 7.02 × 1020 cm-3 suggests the presence of stacking defects in the ZnO lattice. The Raman peak at 274 cm-1 is attributed to lattice defects introduced by In dopants.
authors.affiliation: Physics Programme, School of Distance Education, Universiti Sains Malaysia, 11800, Penang, Malaysia; Institute of Nano-optoelectronics Research and Technology, Sains@USM, 11900, Penang, Malaysia.
authors.forename: K G
authors.initials: KG
authors.lastname: Saw
authors.affiliation: Physics Programme, School of Distance Education, Universiti Sains Malaysia, 11800, Penang, Malaysia.
authors.forename: N M
authors.initials: NM
authors.lastname: Aznan
authors.affiliation: School of Physics, Universiti Sains Malaysia, 11800, Penang, Malaysia.
authors.forename: F K
authors.initials: FK
authors.lastname: Yam
authors.affiliation: Institute of Nano-optoelectronics Research and Technology, Sains@USM, 11900, Penang, Malaysia.
authors.forename: S S
authors.initials: SS
authors.lastname: Ng
authors.affiliation: School of Materials and Mineral Resources Eng., Universiti Sains Malaysia, 14300, Nibong, Tebal, Malaysia.
authors.forename: S Y
authors.initials: SY
authors.lastname: Pung
mesh_terms: D003460:Crystallization; D007204:Indium / Q000737:chemistry*; D010316:Particle Size; D013059:Spectrum Analysis, Raman; D015034:Zinc Oxide / Q000737:chemistry*
chemical_list: D007204:Indium; C047711:indium oxide; D015034:Zinc Oxide