Preparation and Characterization of (Al, Fe) Codoped ZnO Films Prepared by Sol–Gel

Abstract

In this research, Al-doped and (Al, Fe) codoped ZnO films were prepared on glass substrate by the sol–gel method. The surface morphology, structure, and optical property were characterized by scanning electron microscope (SEM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and Ultraviolet-Visible-Near-infrared (UV-Vis-NIR) spectroscopy. The film surface morphologies all exhibited granular characteristics. With the Fe doping concentration increasing, the codoped films had smaller grain size and tended to be smoother. XRD analysis revealed that all films had a hexagonal wurtzite structure. The codoping can contribute to more Al and Fe ions entering the ZnO crystal structure, but result in the crystalline degree of the films decreasing. XPS results showed that the Al and Fe irons in the films exist in the form of trivalent. Moreover, the doped films had higher transmission, especially for codoped (Fe:Al = 3) film, but their absorption edge shifted to the short-wavelength direction.

Melioration of Electrical and Optical Properties of Al and B Co-Doped ZnO Transparent Semiconductor Thin Films

“…When the ZnO-based thin film was irradiated with UV light, the photogenerated electrons could be excited from the valence band and move into the conduction band. If the low energy level in the conduction band was filled, the electrons would only jump to the high energy state, which corresponded to bandgap broadening [4].…”

“…Coatings 2021, 11, x FOR PEER REVIEW 9 of 1 would only jump to the high energy state, which corresponded to bandgap broadening [4]. The dependence of the natural logarithm of the absorption coefficient (ln α) on the incident photon energy (h) near the band edge is known as the Urbach relation, which can be expressed as follows [34,35]:…”

“…Zinc oxide (ZnO) is an abundant raw material. It is a II-VI group wide-bandgap oxide semiconductor and exhibits superior physical properties such as chemical and thermal stability, biocompatibility, high radiation resistance, good optical transparency in the visible spectral range, high quantum yield, a wide range of electrical resistivity and high voltagecurrent nonlinearity [1][2][3][4][5]. It is a promising semiconductor material for electronic and optoelectronic applications, especially in excitonic devices [6].…”

“…The substitution of two kinds of extrinsic group III dopants (namely dual-donors simultaneously co-doping) is considered an effective approach to enhance the electrical characteristics and optical parameters of ZnO thin films [17][18][19]. The ionic radii of B 3+ (0.23 Å) and Al 3+ (0.51 Å) are smaller than the ionic radius of Zn 2+ (0.74 Å), allowing easy substitution of B 3+ and Al 3+ for Zn 2+ and decrement of the lattice parameters, which leads to volume shrinkage of the unit cells [4,20].…”

Synthesis of Al‐doped and Fe–doped ZnO nanoparticles as UV filters in sunscreens

“…According to previous works, Al-doped, Fe-doped or Al and Fe-codoped ZnO thin films were successfully prepared by different methods such as RF magnetron sputtering, [11] spray pyrolysis, [12] or dip-coating solgel. [13,14] Although effective, both these techniques usually require complicated procedures, expensive chemicals and instrumental set-up. They also seem to be more suitable for the synthesis of thin film synthesis than that of nanoparticles used in sunscreen formulations.…”