Xuejian Du

Electrical and optical characterizations of β-Ga2O3:Sn films deposited on MgO (110) substrate by MOCVD

Tin-doped β-Ga2O3 (β-Ga2O3:Sn) films doped with different tin concentrations were deposited on MgO (110) substrates by metal organic chemical vapor deposition (MOCVD) at 700 °C. The effect of doping on the structural, electrical and optical properties of the films was investigated. The 10% Sn-doped film exhibited the best electrical conductivity properties with the lowest resistivity about 5.21 × 10−2 Ω cm, which is over ten orders of magnitude lower than the un-doped film. Micro-structural analysis revealed that the film with 10% Sn content had a clear in-plane relationship of β-Ga2O3 (100) ‖ MgO (110) with β-Ga2O3 (01) ‖ MgO (111). The average transmittance of the samples in the visible range exceeded 87% and the optical band gap of the films varied from 4.12 to 4.80 eV.

Preparation and characterization of single crystalline anatase TiO2 films on LSAT (001) by MOCVD

TiO2 thin films with anatase structure have been prepared on [LaAlO3]0.3[SrAl0.5Ta0.5O3]0.7 (LSAT) (001) substrates by metalorganic chemical vapor deposition (MOCVD) in the substrate temperature range of 500–650 °C. Tetrakis-dimethylamino titanium (TDMAT) is used as the organometallic source and oxygen as oxidant. Structural and optical properties of the films as well as the epitaxial mechanism have been investigated by X-ray diffraction (XRD), transmission electron microscopy (TEM) and optical transmittance spectra. The measurements and analyses show that the TiO2 film grown at 550 °C exhibits the best crystallinity with anatase structure. The obtained TiO2 film is a single-crystalline epitaxial film with no twins and very few defects. The heteroepitaxial relationship is determined as TiO2 (001) ‖ LSAT (001) with TiO2 [100] ‖ LSAT 〈100〉. The average transmittance of the film deposited at 550 °C in the visible wavelength is about 84% with an optical band gap of about 3.27 eV.

Structural and optical properties of Al2xIn2−2xO3 films prepared by metal-organic chemical vapor deposition

Tunable band gap Al2xIn2−2xO3 films with different compositions x[Al/(Al + In) atomic ratio] were grown on MgO (110) substrates by the metal organic chemical vapor deposition (MOCVD) method at a temperature of 700 °C. The effects of different Al concentrations on the structural and optical properties of the obtained films were discussed in detail. The film deposited with an Al concentration of x = 0.1 showed single crystalline bixbyite In2O3 structure with Al0.2In1.8O3 (110)‖MgO (110), while the films with x = 0.3 and 0.5 had polycrystalline structures, and the sample prepared with x = 0.9 exhibited γ-Al2O3 structure. The transmittances of all the samples exceeded 80% in the visible region. The optical absorption edges of the films shifted to short wavelength, and the bandgap of the prepared films could be monotonously modulated from 3.73 eV to 5.82 eV as the Al concentration increased from 0.1 to 0.9.

Preparation and characterization of Al{sub 2x}In{sub 2−2x}O{sub 3} films deposited on MgO (1 0 0) by MOCVD

Highlights: • Ternary Al{sub 2x}In{sub 2−2x}O{sub 3} alloy films were deposited on MgO (1 0 0) by MOCVD. • The microstructure of the Al{sub 2x}In{sub 2−2x}O{sub 3} films were studied upon HRTEM. • Al{sub 2x}In{sub 2−2x}O{sub 3} alloy films exhibited great optical transparency in the visible wavelength range. • The band gap of the Al{sub 2x}In{sub 2−2x}O{sub 3} films can be modulated by controlling the Al contents in the samples. - Abstract: The ternary Al{sub 2x}In{sub 2−2x}O{sub 3} films with different compositions x[Al/(Al + In) atomic ratio] have been fabricated on the MgO (1 0 0) substrates by the metal organic chemical vapor deposition (MOCVD) method. The influence of different Al contents on the structural, optical and electrical properties of Al{sub 2x}In{sub 2−2x}O{sub 3} films has been studied. The structural studies reveal a change from single crystalline structure of cubic In{sub 2}O{sub 3} to amorphous as the Al content increases. The average transmittances of all samples in the visible range are over 80%. The optical band gap is observed to increase monotonically from 3.67 to 5.38 eV as the Al content increases from 0.1 to 0.9.