Physical properties of nanostructured ZnO thin films deposited by DC magnetron sputtering method with different volume of O2 in carrier gas

Abstract

High-quality ZnO thin films with polycrystalline hexagonal structure and (101) preferentially oriented were deposited on Si and corning glass substrates by reactive direct current magnetron sputtering. The effects of different oxygen concentration in carrier gas on structural, morphological and optical properties have been investigated. The increase of O 2 concentration resulted in the decrease of preferred orientation intensity and peak shifting to lower 2θ values. Scanning electron microscopic images showed a porous tapered columnar structure similar to the zone 1 of Thornton's structure zone model at lower O 2 content and a smooth microstructure similar to the zone T structure at highest O 2 content. AFM images showed that film morphology and surface roughness were influenced by O 2 concentration. UV-Vis-NIR measurements indicated that the UV absorption intensity of samples was increased and shifted to shorter wavelength (blue shift) at higher O 2 concentration. Moreover, the optical band gap increased from 3.91 to 4.41 eV as a function of the oxygen concentration.

Impact of Radio Frequency Plasma Power on the Structure, Crystallinity, Dislocation Density, and the Energy Band Gap of ZnO Nanostructure

“…It is worth noting that the E g value is correlated to several factors, such as the dislocation density, defects (oxygen vacancies, Zn interstitials), strain, random orientation of nanorods, and the quantum size effect of the nanostructure, which have already been proved by the XRD results. , …”

“…24 It is worth noting that the E g value is correlated to several factors, such as the dislocation density, defects (oxygen vacancies, Zn interstitials), strain, random orientation of nanorods, and the quantum size effect of the nanostructure, which have already been proved by the XRD results. 64,65 On the other hand, the increasing band gap is owing to the existence of zinc hydroxide, Zn(OH) 2 . 66 The band gap was found to decrease from 3.26 to 3.22 eV after increasing the RF plasma power from 150 to 300 W as a result of the removal of Zn(OH) 2 from the film or elimination of defect levels after increasing the RF plasma power, which is a more common phenomenon in chemically deposited thin films.…”

Physical properties of aluminum doped Zinc Oxide thin films and single wall carbon nanotubes bilayers with potential application in photovoltaics devices

“…The surface roughness values of AZO thin films were around 55 nm and no clear correlation was observed between the surface roughness and the power used in the processing of AZO films. In the set of AZO thin films, the smallest electrical resistivity value was obtained for the sample processed at 175 W. ZnO electrical conductivity deposited at room temperature is generated due to the electrons from oxygen vacancies and zinc interstitial atoms into the structure [19]; while in the ZnO: Al samples, the electrical conductivity is due to the concentration of free carriers and charge recombination reduction brought out the aluminum doped [20].…”