Resistivity Stability of Ga Doped ZnO Thin Films with Heat Treatment in Air and Oxygen Atmospheres

Abstract

The effect of annealing in air and oxygen on structural, electrical and optical properties of gallium doped ZnO thin films was investigated. The X-ray diffraction patterns showed that the films were highly preferentially oriented along (002) plane. After the heat treatment in air and oxygen environments, the intensity of (002) peak was apparently improved. It was found that heat treatment in air atmospheres lead to increase in surface roughness of the film. The GZO films annealed in oxygen at 673 K exhibited low resistivity of 4.21 × 10 -3 Ω·cm, while the resistivity of film annealed in air showed a slightly higher value of 7.14 × 10 -3 Ω·cm. In addition to this, all films have good optical transmittance about 80% in the visible region. It is found from the photoluminescence studies that the broad visible emissions in GZO films originated from the intrinsic shallow traps (V Zn ) and deep level vacancies (Z ni , O Zn and V O ).

Effect of RF power on the optical, electrical, mechanical and structural properties of sputtering Ga-doped ZnO thin films

“…The effects of the carrier concentration [8], radio-frequency (RF) power [9], working gas pressure [10], substrate temperature, annealing, and heat treatment [11,12] have been intensively investigated in order to decrease the resistivity of ZnO thin films with dopants. These dopants can increase the electron concentration, but they also change the microstructural morphology which usually has a significant influence on the optical and electrical properties.…”

Microwave-Assisted Synthesis and Processing of Al-Doped, Ga-Doped, and Al, Ga Codoped ZnO for the Pursuit of Optimal Conductivity for Transparent Conducting Film Fabrication

“…The characteristic peak of metallic Al (72.7 eV) was not observed in both powders . The XPS spectra of GZO and AGZO (Figure b) show peaks present at 1117.79 and 1118.71 eV, respectively, which are characteristic of Ga 2p 3/2 in Ga–O . Metallic Ga with a binding energy of 1116.70 eV was not observed in any of these two powder samples, confirming the presence of Ga 3+ as dopant.…”

“…33 The XPS spectra of GZO and AGZO (Figure 2b) show peaks present at 1117.79 and 1118.71 eV, respectively, which are characteristic of Ga 2p 3/2 in Ga−O. 34 Metallic Ga with a binding energy of 1116.70 eV was not observed in any of these two powder samples, confirming the presence of Ga 3+ as dopant. In addition, small amounts of C (284.90−285.89 eV) and Cl (200.09 eV) were also present at impurity levels.…”

Enhanced NO2 Sensing Property of ZnO by Ga Doping and H2 Activation

“…The main species of O1 on the lower binding energy side of the O1s spectra are perhaps attributed to the coordination of oxygen in ZnO lattice. While the higher binding energy species of O2, centered at 532.2 eV, is attributed to oxygen defects such as chemisorbed oxygen or OH species on the surface of the ZnO thin film . It is obvious that pure ZnO and GZO annealed in air have relatively higher O2 content as compared with GZO activated by H 2 .…”

“…While the higher binding energy species of O2, centered at 532.2 eV, is attributed to oxygen defects such as chemisorbed oxygen or OH species on the surface of the ZnO thin film. [33,34] It is obvious that pure ZnO and GZO annealed in air have relatively higher O2 content as compared with GZO activated by H 2 . This might be resulted by the H 2 reduction decreasing the oxygen interstitial and thus release the Ga donor.…”