Lattice dynamics of a mist-chemical vapor deposition-grown corundum-like Ga2O3 single crystal

Abstract

The lattice dynamical properties of the corundum-like a-phase of Ga 2 O 3 are investigated by means of Raman scattering experiments and ab-initio calculations. A high-quality, single-crystal thick epilayer was grown on sapphire by the mist-chemical vapor deposition method. The phonon frequencies at the Brillouin zone center of all the Raman-active modes are determined by polarized Raman scattering measurements on an a-Ga 2 O 3 single crystal. By performing backscattering measurements from (0001) and ð10 10Þ faces, all Raman active modes are unambiguously identified. Density functional perturbation theory calculations were carried out to determine the symmetry and the frequency of the a-Ga 2 O 3 lattice modes. We find a good agreement between the theoretical predictions and the Raman spectra. The relative intensity of the different modes and their polarizability are discussed. The Raman spectrum is dominated by a narrow A 1g peak which indicates the high crystalline quality of the layers grown by the mist chemical vapor deposition method. V C 2015 AIP Publishing LLC. [http://dx

Influence of Carrier Gases on the Quality of Epitaxial Corundum-Structured α-Ga2O3 Films Grown by Mist Chemical Vapor Deposition Method

“…The Raman peaks at 418 cm −1 and 749 cm −1 belong to the sapphire substrate [14]. The Raman peaks located at 431.3 cm −1 , 577 cm −1 , and 692 cm −1 are the Raman-allowed vibrational modes of E g , A 1g , and E g for α-Ga 2 O 3 , respectively, and are consistent with the theoretical calculations [15]. The high-frequency A 1g mode at 577 cm −1 mainly involves the vibration of oxygen atoms perpendicular to the c-axis.…”

Ordinary dielectric function of corundumlike α−Ga2O3 from 40 meV to 20 eV

“…For a proper data modeling routine, we therefore have to make an assumption about the extraordinary part of the dielectric tensor, i.e., the characteristic energy ω TO,l , broadening factor γ TO,l , and amplitudes S l of the two A 2u modes. For this purpose, we carefully compared the energy positions of Raman active phonon modes of α-Al 2 O 3 and α-Ga 2 O 3 , which are fully explored [39,63]. Next, the results for the ordinary dielectric functions of α-Al 2 O 3 and α-Ga 2 O 3 were compared.…”

“…Next, the results for the ordinary dielectric functions of α-Al 2 O 3 and α-Ga 2 O 3 were compared. [63] and [39], and the infrared-active modes of sapphire were taken from Ref. [61].…”

“…Phonon modes were investigated by Raman spectroscopy [39]. Electrical, optical, and magnetic properties of doped material were also studied [40].…”

Prediction of the Abnormal Properties in Monolayer α‐AlxGa2−xO3

“…According to the thermal conductivity () where V 0 is the volume of a unit cell, the heat capacities (), group velocities (), and phonon lifetimes () are examined by Figure 6b–d. The phonon lifetimes obtained in this work are compared with the experimental results solving the equation of , where is the Raman linewidth and ℏ is a constant equal to 5.3 × 10 −12 cm −1 s. [ 32,33 ] The experimental and theoretical phonon lifetimes of the bulk α‐Ga 2 O 3 are listed in Table 2 . There are obvious differences between the phonon lifetimes obtained by calculations and experiments since the GGA tends to overestimate the lattice parameters.…”