Effect of oxygen partial pressure on the behavior of dual ion beam sputtered ZnO thin films

Abstract

Undoped ZnO thin films were grown on p-type Si (1 0 0) substrates at different oxygen partial pressure by dual ion beam sputtering deposition system at a constant growth temperature of 400 • C. The crystallinity, surface morphology, optical, elemental and electrical properties of these ZnO thin films was studied. The minimum value of full-width at half-maximum of the θ -rocking curve obtained from x-ray diffraction of the ZnO (0 0 2) plane, was reported to be 0.1865 • from ZnO film grown at 50% of (O 2 /(O 2 + Ar))%. Crystalline property of ZnO films was observed to degrade with the increase in oxygen partial pressure. Photoluminescence measurements demonstrated sharp near-band-edge emission at ∼381 nm at room temperature. X-ray photoelectron spectroscopy study revealed presence of oxygen interstitials and vacancies as point defects in ZnO films. Electrical resistivity of ZnO was found to increase with the increase in oxygen partial pressure.

Molybdenum and tungsten oxide based gas sensors for high temperature detection of environmentally hazardous sulfur species

“…Those are located at 530.34, 531.15 and 532.85 eV. The former is in a good match with the values presented in literature for lattice O 2− ion in SrMoO 4, while the latter corresponds to that reported for interstitial oxygen ions; the last photoelectron energy aligns with the values reported for chemisorbed oxygen (surface adsorbed oxygen) [64][65][66][67][68][69][70] The corresponding full width at half maximum (FWHM) values for lattice, interstitial and adsorbed oxygen ions are 1.2, 1.9 and 1.8 eV, respectively. The broad nature of the interstitial component can be interpreted as the contribution of the oxygen deficient regions [69] In this work, 50 at% of O 2− ions were located at regular lattice sites, while 37 at% of O 2− ions was positioned at interstitials, with the remaining 13 at% was detected as chemi/physi-adsorbed.…”

Stable co-emission of UV, green and red light in ZnO thin films with rapid annealing treatment

“…One peak centered at 530.8 eV is attributed to O 2− ions array on the wurtzite structure of ZnO, labeled as O1; another peak centered at 531.8 eV is associated with O 2− ions which are in oxygen deficient regions within the matrix of ZnO, labeled as O2. Some experimental results show that there is still a third component located at 532.6 eV in some cases, which can be ascribed to the specific species such as CO 3 , adsorbed H 2 O, or O 2 on the ZnO thin film surface [23]. From the above fitting results, it can be known that all the films contain many oxygen vacancy defects, which is in agreement with the actual situation.…”

“…The distance between the two peaks is 23.0 eV, being close to the standard difference value. The values of binding energy and their difference value obtained from the XPS spectra indicate that the Zn atoms are in the Zn 2+ oxidation state in the films [23,24]. Fig.…”

“…3(c) shows the high resolution XPS spectra of O 1s. It can be seen that they are asymmetry, suggesting that at least there exists two oxygen species in the ZnO thin films [23]. In order to acquire more accurate information, we performed multi-Gaussian fitting for the spectra as shown in Fig.…”

Bias-dependent photo-detection of dual-ion beam sputtered MgZnO thin films

“…DIBSD system [22,23] was used to deposit MgZnO thin films of thickness ∼600 nm in the base pressure of 3 × 10 −4 mbar on p-Si (001) substrates. During the growth process, a secondary direct-current assist ion source with the primary RF ion source was deployed to increase the film adhesion to the substrate and to eventually realize more uniform film surface.…”