Isotopic study of Raman active phonon modes in β-Ga₂O₃

Abstract

The Raman-active phonon modes of β-Ga2O3 in two O isotope compositions are studied by theory and experiment. Raman modes dominated by different, inequivalent O lattice sites were identified and can be used for the investigation of point defects.

Comprehensive Raman study of orthorhombic κ/ε-Ga2O3 and the impact of rotational domains

“…The high-frequency modes are hence solely governed by O lattice site vibrations. A similar behavior was previously observed for β -Ga 2 O 3 , where the relative contribution to a Raman mode's energy from Ga (or O lattice sites) decreased (or increased) with rising Raman frequency 63.…”

“…While the Raman-and IR-active phonons of β -Ga 2 O 3 have been calculated theoretically and verified experimentally in a number of publications. [59][60][61][62][63][64] , comprehensive Raman spectra of κ-Ga 2 O 3 are not yet available in the literature. One previous work 65 investigated the IR-and Raman-active phonons of orthorhombic gallium-substituted epsilon iron oxide (κ/ε − Ga 0.5 Fe 1. structures.…”

“…An alternative to overcome the challenges posed by the strong substrate signal in the confocal geometry is the employment of cross-sectional Raman spectroscopy, in which the laser is focused onto the sample's edge to maximize or minimize the signal contributions from the film or substrate, respectively. This approach was successfully applied in a preceding study 63 , in which the edge of a square-shaped (010)-oriented homoepitaxially grown β -Ga 2 O 3 thin film was irradiated to determine the Raman modes associated with it. We provide an analytical tool to treat the effect of the domain structure on the Raman spectra, paving the way to discriminating domain structured from monocrystalline films in future studies.…”

Structural and optoelectronic characteristics of β-Ga2O3 epitaxial films with Zn alloying and subsequent oxygen annealing

“…Except for the signals from the sapphire substrate, the Raman peaks related to the b-Ga 2 O 3 can be divided into three categories: high-frequency sections at 661.5 cm À1 and 770.1 cm À1 are ascribed to the stretching and bending vibration modes of GaO 4 ; medium frequency sections at 351.0 cm À1 and 480.7 cm À1 are associated with the GaO 6 bending vibration modes; the low-frequency sections at 147.4 cm À1 , 172.0 cm À1 and 203.6 cm À1 can be pertained to the vibration and translation modes of the GaO 4 -GaO 6 chains. 43,44 After Zn alloying, due to the local strain caused by the introduction of impurities, the intensity of all peaks becomes weak, and some even disappear completely. 45,46 To examine the solar-blind UV photodetection properties of these films, we constructed MSM detectors consisting of twentyfive pairs of gold interdigitated electrodes (thickness controlled at B50 nm) using photolithography and lift-off processes.…”

Ferroelectric α‐In2Se3 Wrapped‐Gate β‐Ga2O3 Field‐Effect Transistors for Dynamic Threshold Voltage Control

“…Raman peaks observed at 170, 200, and 347 cm −1 correspond to A 2 g , A 3 g , and A 5 g modes of β‐Ga 2 O 3 , respectively. [ 24–26 ] The other peaks observed at ≈89, 104, 180, and 196 cm −1 correspond to E 2 , A 1 1 , E 4 , and A 1 3 modes of α‐In 2 Se 3 , respectively. [ 27,28 ] Except for the Raman modes corresponding to α‐In 2 Se 3 and β‐Ga 2 O 3 , an additional peak near 143 cm −1 with a broad spectrum was observed from the area of α‐In 2 Se 3 /β‐Ga 2 O 3 heterojunction.…”