Temperature-dependent Photoluminescence Research Articles

Temperature dependence of photoluminescence kinetics and scintillation properties of LuY2(Al5-xScx)O12:Ce (x = 1, 1.5, 2) garnet single-crystalline films

The temperature dependence of photoluminescence (PL) kinetics and scintillation properties were investigated in LuY2(Al5-xScx)O12:Ce (x = 1, 1.5, 2) garnet single-crystalline films grown by the isothermal liquid phase epitaxy method. With the increase of Sc content, the Ce3+ 5d1 level was shifted to higher energy while the Ce3+ 5d2 level was shifted to lower energy due to the decrease in crystal field splitting of the 5d levels. Activation energy of thermal quenching, determined from temperature-dependent PL decay times, decreased with increasing Sc content. At room temperature, the decrease of light yield (LY) value with increasing Sc content is caused by the thermal ionization process. LuY2(Al4Sc)O12:Ce showed a LY value of 510 photons/MeV when excited by 5.5 MeV α-particles, which is ∼21 % larger than that of Lu2Y(Al4Sc)O12:Ce due to a smaller bandgap Eg of the former.

Structural and temperature-dependent photoluminescence properties of NaBaBO3:Ce3+,Tb3+ phosphors synthesized using the combustion method

This study explores the structural and temperature-dependent photoluminescence of Ce3+ and Tb3+ doped NaBaBO3 phosphors, synthesized via combustion. Analysis of their crystal structures confirmed excellent alignment with the standard PDF#98–008-0110. Investigation into both room and low-temperature photoluminescence revealed that the dopants have a significant effect on emission spectra. Ce3+-doped samples exhibited excitation peaks at 275 nm and 358 nm, leading to a primary emission at 419 nm, with enhanced low-temperature emission suggesting reduced non-radiative processes. Tb3+-doped phosphors showed excitation from 250 to 377 nm and emissions from blue to deep red, including strong green emission at 550 nm due to 5D4→7F5 transitions. Optimal doping was found at 1 mol% for Ce3+, while Tb3+ showed increased luminescence up to 3 mol%, with concentration quenching observed beyond these points. The study indicates dipole–dipole interactions dominate Ce3+ concentration quenching, whereas Tb3+ involves both electric dipole and quadrupole interactions. This analysis provides insights into enhancing luminescent efficiency and suggests NaBaBO3:xCe3+,Tb3+ phosphors' potential in advancing white LED technology, highlighting their stable luminescent properties at low temperatures.

Temperature-dependent photoluminescence of novel Eu3+, Tb3+, and Dy3+ doped LaCa4O(BO3)3: Insights at low and room temperatures

This study explores the structural and optical qualities of LaCa4O(BO3)3 (LACOB) phosphors doped with Eu3+, Dy3+, and Tb3+ using a microwave-assisted sol-gel technique. It uncovers oxygen-related luminescence defects in LACOB, highlighting emission peaks at 489 and 585 nm for Dy3+, a distinct sharp peak at 611 nm for Eu3+ in the red spectrum, and a notable green emission for Tb3+ due to specific transitions. The photoluminescence (PL) analysis indicates that luminescence is optimized through precise doping, leveraging dipole interactions, and localized resonant energy transfer, which are influenced by dopant concentration and spatial configuration. Temperature studies show emission intensity variations, particularly noticeable below 100 K for Tb3+ doped samples, demonstrating the nuanced balance between thermal quenching and luminescence efficiency. This temperature dependency, alongside the identified optimal doping conditions, underscores the potential of these materials for advanced photonic applications, offering insights into their thermal behavior and emission mechanisms under different conditions.

Synthesis and erudite insight into the structural, luminescence and thermal sensing characteristics of Sm3+ incorporated [formula omitted]-BaB2O4 novel phosphors

In this paper, we have presented the comprehensive characterization of red-light-emitting novel β-BaB2O4:xSm3+ (x = 0.5, 0.75, 1, 1.5, and 2 mol%) phosphor samples synthesized by making use of solid-state reaction method. The XRD patterns verified the successful synthesis and in-depth analyses were carried out to explore the structural, luminescence, and thermal properties. Notably, the introduction of Sm3+ through doping did not result in any substantial alterations in the crystal structure. Photoluminescence (PL) emission spectra exhibited 4 distinct peaks for 401 nm excitation. Out of these 4 peaks, the prominent peak was present at 601 nm, attributed to the magnetic dipole-allowed transition 4G5/2 → 6H7/2. The colorimetric analysis revealed the correlated color temperature (CCT) to be around 1700 K, accompanied by 99.9 % colour purity. The optimal doping concentration, before luminescence quenching, was identified as 1 mol%, with multipole-multipole interactions identified as the predominant quenching mechanism. Diffuse reflectance spectroscopy (DRS) studies on β-BaB2O4:1%Sm3+ confirmed characteristic peaks corresponding to Sm3+ transitions, revealing an ionic bonding nature between Sm3+ and the host. Also, the direct optical band gap was determined to be 5.62 eV. Furthermore, the optimized phosphor demonstrated exceptional temperature-dependent photoluminescent (TDPL) properties, exhibiting a negligible (∼5 %) decrease in emission intensity for prominent peaks even at 440 K. Overall, the phosphors displayed high activation energy, significant thermal stability, and thermal sensing properties, making them promising candidates for various optoelectronic applications.

Controlling the Orientation-Dependent Second Harmonic Generation in Hybrid Germanium Perovskite Crystals.

Manipulating the crystal orientation plays a crucial role in the conversion efficiency during second harmonic generation (SHG). Here, we provide a new strategy in controlling the surface-dependent anisotropic SHG with the precise design of (101) and (20) MAGeI3 facets. Based on the SHG measurement, the (101) MAGeI3 single crystal exhibits larger SHG (1.3 × (20) MAGeI3). Kelvin probe force microscopy imaging shows a smaller work function for the (101) MAGeI3 compared with the (20), which indirectly demonstrates the stronger intrinsic polarization on the (101) surface. X-ray photoelectron spectroscopy confirms the band bending within the (101) facet. Temperature-dependent steady-state and time-resolved photoluminescence spectroscopy show shorter lifetime and wider emission band in the (101) MAGeI3 single crystal, revealing the higher defect states. Additionally, powder X-ray diffraction patterns show the (101) MAGeI3 possesses larger in-plane polar units [GeI3]- density, which could directly enhance the spontaneous polarization in the (101) facet. Density functional theory (DFT) calculation further demonstrates the higher intrinsic polarization in the (101) facet compared with the (20) facet, and the larger built-in electric field in the (101) facet facilitates surface vacancy defect accumulation. Our work provides a new angle in tuning and optimizing hybrid perovskite-based nonlinear optical materials.

Spectral studies of thermally stable Dy3+/Sm3+ co-doped Li2Ba5W3O15 phosphors for warm white LEDs

In the current study, a series of Li2Ba5W3O15: RE3+ (RE = Dy, Sm) [LBW:Dy3+/Sm3+] phosphors were prepared using a high-temperature solid-state method. X-ray diffraction, Scanning electron microscopy with energy-dispersive x-ray analysis scans showed that the crystal form was consistent with the standard LBW and comprised small irregularly shaped particles. Diffuse reflectance spectral (DRS) data was utilized to calculate the band gaps. Fluorescence study shows that LBW material doped with Dy3+ and Sm3+ yield distinct colors at 496 nm (blue) for Dy3+ and 582 nm (green-yellow), 612 nm (yellow), and 669 nm (red) for Sm3+ when excited by near-ultraviolet (336 nm) light. The observation of energy transfer between Dy3+ and Sm3+ ions play a role in modifying the luminescence of LBW:Dy3+/Sm3+ co-doped phosphors. With a constant excitation wavelength (λ Ex), different levels of activator doping lead to a change in the emission colors from their neutral white light to a deep orange-red region for LBW:Dy3+/Sm3+ phosphors. The decay curves demonstrate a decrease in lifetime with an increase in the concentration of activator ions (Sm3+). For D3S5 phosphor, the temperature-dependent photoluminescence characteristics were analyzed under λ Ex = 336 nm excitation. The results indicate excellent luminescence thermal stability with an activation energy of 0.16 eV at λ Ex = 336 nm. With its low color-correlated temperature and good thermal stability, the prepared phosphor sample shows potential as a solid-state emitting phosphor that can be used with UV chip stimulation for warm white LED applications.

Tailoring structural ordering and optical characteristics of In0.49Ga0.51P films via Zn doping engineering by MOCVD

In0.49Ga0.51P is highly promising due to its favorable lattice-matching properties with GaAs, making it well-suited for various device applications. This study investigated the influence of Zn doping on the ordering and optical properties of In0.49Ga0.51P grown on GaAs using metalorganic chemical vapor deposition. By precisely controlling the doping flow, the ordering degree of In0.49Ga0.51P was systematically modulated. The luminescence origin and bandgap characteristics of In0.49Ga0.51P were examined through temperature-dependent photoluminescence and Hall measurements. The findings demonstrate a noticeable peak shift, accompanied by a increase in the bandgap and a corresponding decrease in the ordering degree as the Zn concentration increases.

Temperature-dependent excitonic emission characteristics of highly crystallized carbon nitride nanosheets

Highly-crystallized carbon nitride (HCCN) nanosheets exhibit significant potential for advancements in the field of photoelectric conversion. However, to fully exploit their potential, a thorough understanding of the fundamental excitonic photophysical processes is crucial. Here, the temperature-dependent excitonic photoluminescence (PL) of HCCN nanosheets and amorphous polymeric carbon nitride (PCN) is investigated using steady-state and time-resolved PL spectroscopy. The exciton binding energy of HCCN is determined to be 109.26 meV, lower than that of PCN (207.39 meV), which is attributed to the ordered stacking structure of HCCN with a weaker Coulomb interaction between electrons and holes. As the temperature increases, a noticeable reduction in PL lifetime is observed on both the HCCN and PCN, which is ascribed to the thermal activation of carrier trapping by the enhanced electron–phonon coupling effect. The thermal activation energy of HCCN is determined to be 102.9 meV, close to the value of PCN, due to their same band structures. Through wavelength-dependent PL dynamics analysis, we have identified the PL emission of HCCN as deriving from the transitions: σ*–LP, π*–π, and π*–LP, where the π*–LP transition dominants the emission because of the high excited state density of the LP state. These results demonstrate the impact of high-crystallinity on the excitonic emission of HCCN materials, thereby expanding their potential applications in the field of photoelectric conversion.

Tunable emission color from lead-free zero-dimensional Mn2+-doped Cs3InCl6 Single Crystals

In recent years, the magneto-optical properties of zero-dimensional metal halides have attracted widespread interest. In this study, we employed a vacuum solid-state reaction method to synthesize zero-dimensional, lead-free, and all-inorganic Cs3InCl6 single crystals (SCs). In addition to the blue emission of self-trapped excitons (STEs) inherent to pristine Cs3InCl6, the strategic doping with Mn2+ ions not only facilitates multicolor emissions but also significantly boosts the photoluminescence quantum yield (PLQY) from a modest 1.21% to an impressive 32.18%. We carried out an exhaustive investigation into the fundamental mechanisms responsible for these multicolor emissions and the intricate compositional transitions that ensue. Furthermore, the pronounced correlation between temperature-dependent photoluminescence (PL) and magnetic characteristics unveiled the genesis of ferromagnetism within both the pristine and Cs3InCl6: xMn2+ samples. The doping-induced modifications in magnetic behavior furnish a coherent explanation for the anomalous inverse temperature dependence emission wavelength shift. Our research highlights the adjustable PL and magnetic attributes of Mn2+ doped Cs3InCl6, yielding invaluable insights that are poised to advance its application in the next wave of optoelectronic and magnetic technologies.

Optical Detection of Passive Thermal Lattice Deformation of Monolayer WS2 in van der Waals Heterostructures of WS2/h-BN

Van der Waals heterostructures (vdWHs) of the constituent two-dimensional (2D) layered materials are quickly emerging as functional structures for diverse novel electronic and optoelectronic devices. To further explore the device applications of the vdWHs, an open question, which is whether the lattice of atomic thin active layer follows the deformation of its neighboring thick layers in a vdWH, needs to be clarified. Herein, the thermal deformation of WS2 monolayers in vdWHs with and without hexagonal boron nitride (h-BN) layers on SiO2/Si substrates is investigated with combined optical spectroscopies of photoluminescence (PL) and Raman scattering. With a developed strategy extracting the pure strain-induced effects from the temperature-dependent PL and Raman scattering spectroscopic results, the relative deformations of the WS2 monolayers and the h-BN layers with respect to the substrate have been identified. Both the Raman and PL results consistently reveal that the lattice variation of the WS2 monolayers passively match the deformation of the h-BN layers, and the WS2 monolayer on the SiO2/Si substrate exhibits the largest strain. These findings have not only demonstrated the passive behavior of the thermal strain of 2D semiconductor monolayers in vdWHs heterostructures, but also paved a way to tailor the thermal strain via designing and constructing vdWHs.

Oxygen-Vacancy-Mediated Large Binding Energy Exciton Dissociation in Nb3O7(OH) Nanorods with High Electron Mobility for CO2 Photoreduction.

Despite the excellent performance of Nb3O7(OH) in dye-sensitized solar cells and catalysis, its charge separation, transport, and structural properties remain poorly understood. Herein, the Nb3O7(OH) nanorods were prepared, and their structural characteristics, optoelectronic properties, and carrier mobility were also analyzed and investigated through a series of complex characterizations. Theoretical prediction suggested that the exciton binding energy of Nb3O7(OH) could be as high as 100.49 meV. The temperature-dependent photoluminescence (PL) of Nb3O7(OH) nanorods revealed two activation energies, and a higher proportion of long-lived components observed in the photoluminescence decay indicated effective electron trapping. That is, two energy states were present, hindering photogenerated charge recombination and promoting photocatalytic action. Current-voltage characteristics of the Nb3O7(OH) nanorod film were analyzed, revealing an ultrahigh carrier mobility of ∼310 cm2/V·s, ensuring fast and efficient electron transfer. Furthermore, Nb3O7(OH) nanorods were employed to reduce CO2, resulting in the effective production of CO and CH4. Overall, considering the presence of hydroxyl pairs on the surface of Nb3O7(OH), which facilitate the formation of the frustrated Lewis acid-base pairs and the activation of CO2, together with its effective electron trapping and charge transport, give Nb3O7(OH) nanorods a promising potential for CO2 reduction.

Semi-insulating [formula omitted]-Ga2O3 single crystals through vanadium doping: Growth, Optical and Terahertz characterization

We report the growth of electrically resistive, high quality vanadium-doped β-Gallium Oxide (β-Ga2O3) single crystals via the optical floating zone growth technique. The characteristic properties of such high resistive V-doped β-Ga2O3 are significantly different compared to the undoped, n-type V-doped and other acceptor-doped crystals. We study the optical absorption in the UV–visible and IR range, temperature-dependent photoluminescence, polarization-dependent Raman spectra and the terahertz transmission properties in the 0.2–2.6 THz range. The V-doped insulating Ga2O3 crystals can be used as an alternative insulating substrate for low leakage devices. Further, the strong anisotropy in terahertz transmission makes it an ideal material for optical applications in the THz region.

Tuning magnetic and optical properties in Mn x Zn1−x PS3 single crystals by the alloying composition

The exploration of two-dimensional (2D) antiferromagnetic (AFM) materials has shown great promise and interest in tuning the magnetic and electronic properties as well as studying magneto-optical effects. The current work investigates the control of magneto-optical interactions in alloyed Mn x Zn1−x PS3 lamellar semiconductor single crystals, with the Mn/Zn ratio regulating the coupling strength. Magnetic susceptibility results show a retention of AFM order followed by a decrease in Néel temperatures down to ∼40% Mn concentration, below which a paramagnetic behavior is observed. Absorption measurements reveal an increase in bandgap energy with higher Zn(II) concentration, and the presence of Mn(II) d-d transition below the absorption edge. DFT + U approach qualitatively explained the origin and the position of the experimentally observed mid band-gap states in pure MnPS3, and corresponding peaks visible in the alloyed systems Mn x Zn1‒x PS3. Accordingly, emission at 1.3 eV in all alloyed compounds results from recombination from a 4T1g Mn(II) excited state to a hybrid p-d state at the valence band. Most significant, temperature-dependent photoluminescence (PL) intensity trends demonstrate strong magneto-optical coupling in compositions with x > 0.65. This study underscores the potential of tailored alloy compositions as a means to control magnetic and optical properties in 2D materials, paving the way for advances in spin-based technologies.

The Influence Mechanism of Quantum Well Growth and Annealing Temperature on In Migration and Stress Modulation Behavior.

This study explores the effects of growth temperature of InGaN/GaN quantum well (QW) layers on indium migration, structural quality, and luminescence properties. It is found that within a specific range, the growth temperature can control the efficiency of In incorporation into QWs and strain energy accumulated in the QW structure, modulating the luminescence efficiency. Temperature-dependent photoluminescence (TDPL) measurements revealed a more pronounced localized state effect in QW samples grown at higher temperatures. Moreover, a too high annealing temperature will enhance indium migration, leading to an increased density of non-radiative recombination centers and a more pronounced quantum-confined Stark effect (QCSE), thereby reducing luminescence intensity. These findings highlight the critical role of thermal management in optimizing the performance of InGaN/GaN MQWs in LEDs and other photoelectronic devices.

Molybdate-Templated Luminescent Silver Alkynyl Nanoclusters: Total Structure Determination and Optical Property Analysis.

Two novel MoO42--templated luminescent silver alkynyl nanoclusters with 20-nuclearity ([(MoO42-)@Ag20(C≡CtBu)8(Ph2PO2)7(tfa)2]·(tfa-) (1)) and 18-nuclearity ([(MoO42-)@Ag18(C≡CtBu)8(Ph2PO2)7]·(OH) (2)) (tfa = trifluoroacetate) were synthesized with the green light maximum emissions at 507 and 516 nm, respectively. The nanoclusters were investigated and characterized by single-crystal X-ray crystallography, electrospray ionization mass spectrum (ESI-MS), X-ray photoelectron spectroscopy, thermogravimetry (TG), photoluminescence (PL), ultraviolet-visible (UV-vis) spectroscopy, and density functional theory calculations (DFT). The two nanoclusters differ in their structure by a supplementary [Ag2(tfa)2] organometallic surface motif, which significantly participates in the frontier molecular orbitals of 1, resulting in similar bonding patterns but different optical properties between the two clusters. Indeed, both nanoclusters show strong temperature-dependent photoluminescence properties, which make them potential candidates in the fields of optical devices for further applications.

Photoluminescence investigation of novel red emitting NaLa(1-x)MgTeO6: XSm3+ phosphor with high color purity for n-UV based warm WLEDS and anti-counterfeiting applications

Recently, red phosphors are extensively developed to find applications in phosphor converted white LEDs (pc-WLEDs) and anti-counterfeiting. In this work, samarium doped sodium lanthanum magnesium tellurate (NaLaMgTeO6:Sm3+) red emitting phosphors have been synthesized for the first time via solid state reaction method. Rietveld refinement of XRD pattern reveals monoclinic crystal structure of NaLaMgTeO6. Under 404 nm (6H5/2 → 4F7/2) n-UV excitation, NLMT:Sm3+ phosphor shows red emission at 643 nm (45/2 → 69/2) with color purity 100 % and the obtained CCT value corresponds to warm light source. Temperature-dependent PL analysis of NLMT:Sm3+ exhibits good thermal stability. The anti-counterfeiting security ink was developed using optimized phosphor and the information was encrypted on different surfaces using the prepared security ink. The encrypted data was decoded only by n-UV light. The aforementioned results revealed that NLMT:Sm3+ is a highly effective phosphor as a red component for pc-WLEDs and luminescent dye for anti-counterfeiting applications.

Evolved photovoltaic performance of MAPbI3 and FAPbI3-based perovskite solar cells in low-temperatures

Organic-inorganic hybrid perovskites have emerged as an up-and-coming contender for photovoltaic devices owing to their exceptional photovoltaic properties. However, current research predominantly concentrates on their performance under ambient conditions at room temperature. In this work, we delve into the novel territory by investigating MAPbI3-based and FAPbI3-based perovskite solar cells (PSCs) in the temperature range of 300 to 150 K. Remarkable efficiency enhancements of nearly 5% and 20% were obtained at 250 and 210 K, respectively. However, further decreasing the temperature impairs the photovoltaic performance. We propose an underlying mechanism influencing the performance change in perovskite devices at low temperatures by examining the temperature-dependent ultraviolet-visible and photoluminescence spectra results. At the beginning of the cooling process, from 300 to 250 K for MAPbI3 and from 300 to 210 K for FAPbI3, the performance enhancement stems primarily from the enhanced open-circuit voltage by the tuned band gap of the perovskite films. Further lowering the temperature would change the perovskite structure, impairing the performance of PSCs. FAPbI3-based PSCs show a better tolerance in low temperatures owing to the more stable perovskite crystal structure. The present findings offer valuable theoretical guidance for preparing outstanding PSCs for low-temperature applications.

Magnetic coupling interaction-related photoluminescence behaviors in all-inorganic manganese chloride perovskites

Manganese halides, as dilute magnetic semiconductor materials, have magnetic coupling interactions that play an essential role in their photoluminescence (PL); however, such interactions remain controversial. AMnCl3 (AMC, A = K, Rb, and Cs) and their hydrates AMnCl3·2H2O (AMCH, A = K, Rb, and Cs) are both in the ABX3 configuration but exhibit a wide variety of structures with different connectivity types and dimensions. Their magnetic coupling interaction has been demonstrated. However, few studies have systematically investigated the PL in conjunction with the magnetic coupling interaction over these chloride compounds. In this paper, the effect of the magnetic coupling interaction on AMC and AMCH PL is mainly revealed by temperature-dependent PL spectra and lifetimes. The MnX6 (X6 = Cl4(H2O)2 or Cl6) cluster connection types affect the Mn2+–Mn2+ distances. The magnetic coupling interaction between MnX6 octahedrons affects the radiative transitions of manganese chlorides, which is influenced by the Mn2+–Mn2+ distance, local symmetry, and water ligand. The Mn2+–Mn2+ distance and the magnetic coupling interaction also affect their lifetimes. Variations in magnetic coupling interactions can shift emission wavelength, especially dual-emissions and near-infrared (NIR) emission at lower temperatures while A+ = K+. This work helps researchers understand the optical process of Mn2+ ions in different manganese compounds and provides new insights into the design of tailored Mn2+ ion phosphors.

Probing multifunctional applications of LiCa2Mg2V3O12: Sm3+ phosphor using Judd-Ofelt analysis and dual mode non-contact optical thermometry

LiCa2Mg2V3O12:Sm3+ phosphors have been prepared by solid state method and analysed by X-ray diffraction, EDX-elemental mapping, UV–VIS-NIR spectroscopy, photoluminescence (PL) and temperature dependent photoluminescence (TDPL). The absorption spectra analysis using Judd-Ofelt theory provides the intensity parameters and manifest the covalent nature of Sm-O bond. The PL spectra monitored at 338 nm excitation exhibits emission peaks of Sm3+ at 567, 617 and 651 nm in addition to the broad band emission of LiCa2Mg2V3O12 host. The Commision Internationale deL’Eclairage (CIE) coordinates, correlated color temperature (CCT) and color rendering index (CRI) values elucidate the efficient yellow emission of phosphors. The radiative parameters are evaluated and have outrageous branching ratio and cross section that aids in visible laser applications. The optical thermometry of phosphor is carried out by utilizing FIR method through selecting spectral modes 6H5/2/VO43-, 6H7/2/VO43- and 6H9/2/ VO43-. The mode 6H9/2/ VO43- have higher absolute sensitivity (Sa) and relative sensitivity (Sr) values of 0.4418 K−1 and 1.6079% K−1. The temperature resolution of modes are 0.1633, 0.1677 and 0.1563 K respectively. The thermochromic study reveals the high chromaticity shift (Δs = 0.1869) of phosphor and the Sa(x) and Sr(x) values evaluated based on CIE coordinates are 0.0011 K−1 and 0.2407% K−1 respectively. The PL and TDPL characteristics of prepared phosphor suggest that it have multifunctional application in the fields of lasers, thermo-sensors, thermochromic displays and LEDs.

Anisotropy of optical transitions in β-Ga2O3 investigated by polarized photoluminescence excitation spectroscopy

The monoclinic beta-phase of gallium oxide possesses an ultra-wide bandgap that surpasses other wide bandgap materials such as SiC and GaN, making it a promising candidate for power electronic device technologies. We investigate the first fundamental optical transitions in this material, which exhibit a strong directional dependence. To determine the energies and orientations of these transitions, temperature-dependent and angular resolved photoluminescence excitation spectroscopy is applied. We observe a distinct excitation channel located energetically between those of the first two optical transitions Γ1−1 and Γ1−2. While previous absorption edge and reflectance spectroscopy studies have assigned a transition in this spectral range to either the Γ1−1 or the Γ1−2 transition, our findings demonstrate no pronounced polarization dependence of this excitation channel within the (010) plane, an observation not reflected in calculations of the band-to-band transitions in β-Ga2O3.