Epitaxial growth of β-Ga₂O₃ thin films on Ga₂O₃ and Al₂O₃ substrates by using pulsed laser deposition

Abstract

In this work, we have successfully grown high quality epitaxial [Formula: see text]-Ga2O3 thin films on [Formula: see text]-Ga2O3 (100) and Al2O3(0001) substrates using pulsed laser deposition (PLD). By optimizing temperature and oxygen pressure, the best conditions were found to be 650–700∘C and 0.5[Formula: see text]Pa. To further improve the quality of hetero-epitaxial [Formula: see text]-Ga2O3, the sapphire substrates were pretreated for atomic terraced surface by chemical cleaning and high temperature annealing. From the optical transmittance measurements, the films grown at 600–750∘C exhibit a clear absorption edge at deep ultraviolet region around 250–275[Formula: see text]nm wavelength. High resolution transmission electron microscope (HRTEM) images and X-ray diffraction (XRD) patterns demonstrate that [Formula: see text]-Ga2O3(-201)//Al2O3(0001) epitaxial texture dominated the epitaxial oxide films on sapphire substrate, which opens up the possibilities of high power electric devices.

Annealing temperature controlled crystallization mechanism and properties of gallium oxide film in forming gas atmosphere

“…One of them is O 2s core level at 22.8 eV, which is the most probable value for this emission peak. 54,57 The peak-differentiating of Ga 3d peak exhibits that two main peaks represent the Ga 3+ and Ga + valence states located at 20.01-20.19 eV and 18.92-19.22 eV, respectively, which is well consistent with the previous reports. [18][19][20][21][22][23][24][25][26][27][28][29][30][31][32] The Ga 3+ valence state owns higher binding energy while the lower binding energy can be associated with Ga + valence state.…”

“…The annealing temperature dependence of Ga 2 O 3 thin films bandgap extracted by Tauc plot is summarized and exhibited in Figure 3B and the obtained bandgap of Ga 2 O 3 films agrees with previous reports. [20][21][22][23][24][25][26][27][28][29][30][31][32][53][54][55] The extracted E g value of as-deposited Ga 2 O 3 films was 5.03 eV and increased sharply to 5.24 eV after 500 • C annealed, which could be contributed to the transition from amorphous to crystalline property of the film. 30 As the annealing temperature varies from 500 to 700 • C, the E g values remained nearly constant.…”

High‐Quality Si‐Doped β‐Ga2O3 Films on Sapphire Fabricated by Pulsed Laser Deposition

“…The rocking curve around the (À201) reflection peak displays a full width at half maximum of 1.6 , which compares well with β-Ga 2 O 3 of standard quality on c-cut sapphire. [14][15][16] Optical transmittance in the wavelength range from 200 to 800 nm is shown in Figure 2. The spectrum is from only the DOI: 10.1002/pssb.202000362 Pulsed laser ablation is used to form high-quality silicon-doped β-Ga 2 O 3 films on sapphire by alternatively depositing Ga 2 O 3 and Si from two separate sources.…”

“…The rocking curve around the (−201) reflection peak displays a full width at half maximum of 1.6°, which compares well with β‐Ga 2 O 3 of standard quality on c ‐cut sapphire. [ 14–16 ]…”

Magnetron Sputter-Deposited β-Ga2O3 Films on c-Sapphire Substrate: Effect of Rapid Thermal Annealing Temperature on Crystalline Quality

“…In particular, the c-plane (0001) sapphire has been widely employed as a substrate for β-Ga 2 O 3 because of its six-fold symmetry. Crystals of (−201)oriented β-Ga 2 O 3 also exhibit six-fold symmetry and similar thermal expansion coefficients as β-Ga 2 O 3 (α c = 3.15 × 10 −6 K −1 ) and sapphire (α c = ~4.3 × 10 −6 K −1 ) [6,10].…”