Abstract
γ-phase aluminum oxide (γ-Al2O3) films are grown on MgO (100) wafers by metal organic chemical vapor deposition (MOCVD). Post-annealing process is conducted to study the influence of annealing temperature on the properties of the films. Structural analyses indicate that all the deposited and annealed films present a preferred growth orientation of γ-Al2O3 (220) along the MgO (200) direction. And the film annealed at 1100 °C exhibits the best film quality compared with those of the films grown and annealed at other temperatures. Scanning electron microscopy measurements also imply the best surface morphology for the γ-Al2O3 film annealed at 1100 °C, which is in good accordance with the structural analyses. Optical transmittance spectra show good transparency for all the deposited and annealed films in the visible wavelength region with an average transmittance value of 83.5%. The optical bandgaps are estimated to be in the range of 5.56–5.79 eV for the deposited and annealed films. Semiconductor films with high optical transmittance in the visible region as well as wide bandgaps are appropriate for the manufacture of transparent optoelectronic devices and ultraviolet optoelectronic devices.
Highlights
Coatings 2021, 11, 389. https://Oxide semiconductor materials with wide bandgap have a wide range of applications in short-wavelength light-emitting devices, ultraviolet detectors, solar cells, and thin film transistors [1,2,3,4], which have aroused people’s research interest in recent years
The chemical compositions of the Al2 O3 films are investigated by X-ray photoelectron spectroscopy (XPS) measurements
All the results reveal that the annealing process exhibits a prominent influence on the crystal structure of the film, and the sample annealed at the temperature of 1100 ◦ C exhibits the best crystalline quality
Summary
Oxide semiconductor materials with wide bandgap have a wide range of applications in short-wavelength light-emitting devices, ultraviolet detectors, solar cells, and thin film transistors [1,2,3,4], which have aroused people’s research interest in recent years. Al2 O3 is widely used in many fields It can be used as abrasive materials and cutting tools and can be applied to make high-temperature refractory materials and antireflection coatings on glass surfaces [16,17]. MOCVD is a method of vapor phase epitaxial growth using organic metal thermal decomposition reaction It has simple reaction equipment, wide growth temperature range, precise control of deposition parameters, and raw material gas which will not affect the film. Advantages such as obvious changes in doping concentration can be achieved along the film growth. The impact of annealing temperature on the structural and optical properties of the Al2 O3 films was studied systematically in this paper
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