Optical Absorption Measurements Research Articles

Structural, optical, and dielectric properties of double perovskite NdBaFeTiO6

NdBaFeTiO6 compound was synthesized successfully through solid-state reaction method. The compound was found to have a crystalline cubic double perovskite (DP) structure with space group Pm-3m by XRD analysis. Structural refinement was performed to investigate the detail of the structure and was found consistent with the experimental results. Scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDX) and elemental mapping were used to analyze the morphology and elemental composition, revealing the existence of expected chemical composition and uniform distribution of elements within the material. FTIR and Raman spectroscopic techniques were utilized to investigate the vibrational modes and bonding configurations present in the synthesized sample. XPS spectra confirms the existence of photoelectron peaks associated with constituent elements, and also reveals the lattice oxygen and oxygen vacancies. Optical absorbance measurements showed that this material possesses a significant band gap energy of around 4eV, making it a promising candidate for a variety of technological applications. The electrical properties of this double perovskite were investigated using dielectric measurements, both frequency and temperature dependent. At low temperatures, the dielectric constant behaves independently. At higher temperatures, the thermal energy sufficiently enhances the mobility of charge carriers, thereby causing an elevation in dielectric constant of the order of 104 and 103 at low and high frequencies respectively. Moreover, the temperature dependence of the dielectric constant varies for different frequencies.

Thermal and photochemical degradation of CsGeI3 and CsGeBr3: XPS and optical studies

The toxicity of complex lead halides significantly limits the commercialization and practical application of perovskite solar cells. In recent days, lead-free complex lead halides with a perovskite structure have become increasingly popular, among which germanium systems are the least studied. Here we present for the first time a systematic study of the thermal and photochemical stability of perovskite thin films of CsGeI3 and CsGeBr3. The measurements of optical absorbance and X-ray photoelectron spectra (XPS) of core levels and valence bands of Ge-based halide perovskites after light soaking and heat stress were thoroughly performed. It has been found the effect of thermal and photochemical degradation of Ge perovskites which is accompanied by reduction of I:Ge and Br:Ge ratios and appearance of tetravalent metal species fixed in XPS Ge 2p and Ge 3d spectra. The XPS O 1s measurements of irradiated and annealed Ge-based perovskites and their comparison with spectra of GeO2 have shown that formation of Ge4+-species is not due to metal oxidation but owing to defect-mediated hole-doping. While the Ge2+→Ge4+ process lowers the thermal and photochemical stability of Ge-based perovskites and limits their use in photovoltaics, the temperature induced hole doping is favorable for thermoelectric applications.

The broad-spectrum biocide triclosan trigonal crystal: Experimental and DFT-calculated structural, electronic and optical properties

Triclosan, a member of the broad-spectrum biocide class, has seen widespread usage in various household and healthcare-related products worldwide over the past 35 years. However, its extensive use has raised concerns regarding health and environmental impacts. Notably, there is a notable gap in our understanding of the solid-state properties of triclosan, encompassing both experimental aspects, such as optical absorption, and theoretical insights. Expanding upon the established trigonal crystal structure of triclosan, this study employs experimental techniques including X-ray and photoacoustic-based optical absorption, alongside density functional theory (DFT) calculations, to elucidate its structural, electronic, and optical characteristics. Employing the generalized gradient approximation (GGA) DFT exchange-correlation functional and accounting for dispersion effects, optimal lattice parameters were determined with small deviations from experimental measurements (<∼2.2%). The calculations predict that the triclosan trigonal crystal has very close direct band gaps of about 3.44 eV, almost identical to the value of 3.45 eV derived from photoacoustic optical absorption measurements. Analysis of the calculated optical absorption and complex dielectric function underscores the optical isotropy of solid state triclosan. Furthermore, effective mass computations, in conjunction with the band gap results, suggest that triclosan displays electronic characteristics akin to those of a wide direct gap semiconductor.

ОПТИЧНІ ПАРАМЕТРИ ПЛІВОК ПОЛІАНІЛІНУ НА ПОЛІЕТИЛЕНТЕРЕФТАЛАТНОМУ СУБСТРАТІ

Polyaniline (PAn) films, doped with citric acid, were synthesized on a polyethylene terephthalate substrate by chemical oxidative polymerization using ammonium peroxydisulfate as an oxidant. Optical band gap, Urbach energy, steepness parameter, absorption coefficient, extinction coefficient, the number of carbon atoms in a cluster, skin depth, refractive index were calculated. The change in the optical band gap for the synthesized samples was evaluated and it was found that the band gap decreases with increasing thickness of polyaniline films deposited on the polyethylene terephthalate substrate. It is established that the optical energies of the band gap of polyaniline films, estimated by the results of optical absorption measurements using Tauc methods, are in the range of 2.45–2.04 eV for film thicknesses equal to 76–270 nm, respectively. The Urbach energy values of the polyaniline coatings ranged from 0.57 to 2.24 eV with increasing polyaniline film thickness, respectively.The number of carbon atoms per conjugated length, the number of carbon atoms per cluster and refractive index for the present samples were determined. Based on the correlations between the optical energy of the band gap and the refractive index of semiconductors using Moss, Ravindra, Ravindra-Gupta, Reddy-Ahammed, Gerve-Vandamme, Kumar-Singh, Annani and Duffy-Reddy ratios, the value of the refractive index of polyaniline films was calculated. These values of the refractive index of polyaniline films were compared with the values obtained from the experimental results. From the obtained results it is seen that the refractive index of polyaniline films increases with increasing polyaniline film thickness on the polyethylene terephthalate substrate. The values obtained from the Ravindra is the closest to the experimental ones.

Investigating the Structural, Linear/Nonlinear Optical, and Photoluminescence Characteristics of CuO/ZnMn2O4 Nanocomposite for Physicochemical Applications

The structural, optical, and photoluminescence performance of CuO/ZnMn2O4 nanocomposites was investigated for optical applications. Nanocomposites of xCuO/(1-x)ZnMn2O4 (x; 0 to 0.7) were equipped using the sol-gel route. Synchrotron X-ray diffraction data were collected to examine the structural parameters. Rietveld refinement analysis reveals that the crystallite size decreases upon raising x from 0 to 0.7. High-resolution transmission electron microscopy revealed that the distribution of particle sizes demonstrates a relatively broad spectrum within the nanometer range. Raman spectroscopy investigations were applied to examine the structure’s vibrations. Scanning electron microscopy was used to examine the morphology of the formed samples. UV–vis spectrophotometry was applied to collect optical absorbance and reflectance measurements of the samples. Optical energy gap E g was determined utilizing the Kubelka-Munk method. The refractive index investigations were explored based on seven empirical formulas. The nonlinear optical parameters were explored as a function of CuO contents. The influence of CuO amount on the photoluminescence spectra was investigated. CIE chromaticity diagrams showed that all samples have various degrees of blue-violet colors. A significant improvement was achieved in the linear/nonlinear optical performance of nano ZnMn2O4 by forming CuO/ZnMn2O4 heterojunction, supporting the possible use of CuO/ZnMn2O4 nanocomposites in various optical applications.

Synthesis, physical, optical, and transmission properties of terbium oxide-reinforced quinary borate glasses for radiation protection

This study explores the synthesis and characterization of borate glasses doped with varying concentrations of Terbium oxide (Tb4O7). Using the conventional melt-quench method, we investigated the effects of Tb4O7 on the physical, optical, gamma-ray shielding, and mechanical properties of the glass samples. Our findings indicate a significant increase in density with higher Tb4O7 content, attributed to the high molecular weight and density of Tb4O7. Optical properties assessed through UV–Vis spectroscopy revealed increased absorption intensity, a red shift in the absorption edge, and a decrease in the optical band gap, demonstrating enhanced optical absorption and refractive indices. Gamma-ray shielding effectiveness, evaluated using mass attenuation coefficients, half-value layers, and mean free paths, showed superior performance with higher Tb4O7 concentrations. The effective atomic number also increased, enhancing gamma-ray attenuation capabilities. Additionally, the elastic modulus of the glasses improved with higher Tb4O7 content, providing better mechanical stability. Our findings indicate that the density increased from 3.52 g/cm³ for undoped samples to 3.92 g/cm³ for the glass containing 2 mol% Tb4O7. Optical absorption measurements revealed a red shift in the absorption edge from 345.46 nm to 369.54 nm, with a corresponding decrease in the optical band gap from 3.48 eV to 3.18 eV. Gamma-ray shielding performance improved significantly, with the mass attenuation coefficient (GMAC) rising from 0.115 cm2/g to 0.162 cm2/g, while the half-value layer (GHVL) decreased from 3.22 cm to 2.86 cm. Additionally, the elastic modulus increased by 11.58 % as Tb4O7 content increased. These results suggest that Tb4O7-doped borate glasses significantly improve density, optical absorption, gamma-ray shielding, and mechanical strength. Finally, Increasing Tb4O7 content in borate glasses substantially enhances their multifunctional properties, making them suitable for advanced radiation shielding applications.

Optical Characterization of Hydrogel and Silicone Hydrogel Soft Contact Lenses

Contact lenses are biomaterials that have emerged as an alternative to glasses in correcting vision defects. In this study, commercial nesofilcon A (hydrogel-Hy) and delefilcon A (silicone hydrogel-SiHy) daily disposable soft contact lenses were optically examined using UV-visible light spectroscopy. Optical absorption and transmittance measurements of the lenses were taken with a UV-visible spectrophotometer, and their properties of blocking the harmful part of the radiation to the eye and transmitting the harmless part were investigated. From the absorption spectrum, it was seen that the nesofilcon A lens absorbed ultraviolet light better. From the optical absorption coefficient spectra of nesofilcon A and delefilcon A lenses, the absorption edges were obtained as 386 and 325 nm, and the optical band gap values were 3.37 and 3.98 eV, respectively. Additionally, the refractive index profiles of the lenses were plotted. The refractive indices of the lenses at 550 nm wavelength were calculated as 1.55 and 1.77 for nesofilcon A and delefilcon A, respectively. While the delefilcon A lens transmitted visible light well, the nesofilcon A lens blocked UV light better and its refractive index was determined to be closer to the 1.40 the value specified by the manufacturer.

Systematic investigation of the influence of magnetic and non-magnetic ion substitutions in BiFeO3 under similar internal chemical pressure

Polycrystalline Bi1-xRxFeO3 (RHo and Y, x = 0.00, 0.05 and 0.10) compounds were prepared to perform a systematic investigation of the role of chemical nature and effect of internal chemical pressure on the structural, microstructural, magnetic, electric, ferroelectric and optical properties of the compounds. Structural analysis revealed that lattice distortions observed in Ho and Y-substituted compounds were not the same. The lattice parameters were larger in the case of the Y-substitution compared to the Ho-substituted counterpart. Scanning electron micrographs confirmed the formation of dense, well-connected grains exhibiting a reduction in size with increasing substitution. The magnetic properties of BiFeO3 were enhanced through the suppression of the spin structure with the substitution. The substitution of magnetic (Ho3+) ions led to an improvement in remanent magnetization and coercive field, whereas the substitution of non-magnetic (Y3+) ions resulted in enhanced maximum magnetization with negligible coercive field at room temperature. The ferroelectric measurements evidenced that both remanent polarization and coercive fields improved in substituted compounds, attributed to a decrease in charge carriers. Furthermore, the Y3+ ion substitution positively influenced ferroelectric properties by reducing leakage currents compared to the Ho3+ ion substitution. The optical absorption measurements indicated a decrease in the energy band gap of BiFeO3 with substitution, implying alterations in the material's optical characteristics. The ac conductivity studies demonstrated a discernible reduction in the conductivity of the substituted compounds. Specifically, Ho-substitution exhibited a more pronounced magnitude in the decline in conductivity relative to Y-substitution. This outcome signifies the potential efficacy of Ho-substitution in exerting control over the insulating characteristics of the compounds.

3D Lead-Organoselenide-Halide Perovskites and their Mixed-Chalcogenide and Mixed-Halide Alloys.

We incorporate Se into the 3D halide perovskite framework using the zwitterionic ligand: SeCYS (+NH3(CH2)2Se-), which occupies both the X- and A+ sites in the prototypical ABX3 perovskite. The new organoselenide-halide perovskites: (SeCYS)PbX2 (X=Cl, Br) expand upon the recently discovered organosulfide-halide perovskites. Single-crystal X-ray diffraction and pair distribution function analysis reveal the average structures of the organoselenide-halide perovskites, whereas the local lead coordination environments and their distributions were probed through solid-state 77Se and 207Pb NMR, complemented by theoretical simulations. Density functional theory calculations illustrate that the band structures of (SeCYS)PbX2 largely resemble those of their S analogs, with similar band dispersion patterns, yet with a considerable band gap decrease. Optical absorbance measurements indeed show band gaps of 2.07 and 1.86 eV for (SeCYS)PbX2 with X=Cl and Br, respectively. We further demonstrate routes to alloying the halides (Cl, Br) and chalcogenides (S, Se) continuously tuning the band gap from 1.86 to 2.31 eV-straddling the ideal range for tandem solar cells or visible-light photocatalysis. The comprehensive description of the average and local structures, and how they can fine-tune the band gap and potential trap states, respectively, establishes the foundation for understanding this new perovskite family, which combines solid-state and organo-main-group chemistry.

3D Lead‐Organoselenide‐Halide Perovskites and their Mixed‐Chalcogenide and Mixed‐Halide Alloys

AbstractWe incorporate Se into the 3D halide perovskite framework using the zwitterionic ligand: SeCYS (+NH3(CH2)2Se−), which occupies both the X− and A+ sites in the prototypical ABX3 perovskite. The new organoselenide‐halide perovskites: (SeCYS)PbX2 (X=Cl, Br) expand upon the recently discovered organosulfide‐halide perovskites. Single‐crystal X‐ray diffraction and pair distribution function analysis reveal the average structures of the organoselenide‐halide perovskites, whereas the local lead coordination environments and their distributions were probed through solid‐state 77Se and 207Pb NMR, complemented by theoretical simulations. Density functional theory calculations illustrate that the band structures of (SeCYS)PbX2 largely resemble those of their S analogs, with similar band dispersion patterns, yet with a considerable band gap decrease. Optical absorbance measurements indeed show band gaps of 2.07 and 1.86 eV for (SeCYS)PbX2 with X=Cl and Br, respectively. We further demonstrate routes to alloying the halides (Cl, Br) and chalcogenides (S, Se) continuously tuning the band gap from 1.86 to 2.31 eV–straddling the ideal range for tandem solar cells or visible‐light photocatalysis. The comprehensive description of the average and local structures, and how they can fine‐tune the band gap and potential trap states, respectively, establishes the foundation for understanding this new perovskite family, which combines solid‐state and organo‐main‐group chemistry.

Exploring the denaturations in cancer and non-cancer DNA molecules by optical absorption, thermal, and electric measurements: A case study

In this article, we carried out the temperature dependent UV-Visible (UV-Vis) spectroscopy, differential scanning calorimetry (DSC), and electrical studies for normal and cancerous (glioma) DNA samples of single patient. Based on this method, we were able to monitor the denaturation process and thermal stability in these molecules. From the temperature dependent optical absorption data, we calculated various optical parameters for these two types of samples. The optical band gap of these samples were also estimated and discussed as per the experimental conditions. The various optical parameters calculated indicate that mutated (tumor) DNA is less stable than the normal one. From the DSC data, clear melting peaks were observed for the tumor and normal samples. Also various thermodynamic parameters like change in enthalpy (ΔH), entropy (ΔS), and specific heat (Cp) were estimated. From the thermal study, it seems that the tumor DNA is less stable. Further from the electrical or current-voltage (I-V) characteristics data, the resistance for normal DNA decreases with temperature. But for tumor sample, it show anomalous behavior (like decreasing and then increasing trend) with temperature. For electrical transport, small polaron hopping could be the possible transport mechanism in the current sample. Here from these studies, the tumor sample seems more disordered, and structural fluctuations due to the speculated structure could be the best reason for this behavior. If such kind of molecular (at nano scale range) studied are done more vividly, then these calculated parameters of the molecule could be explored for further confirmation/diagnostics of the diseases in addition to clinical investigations.

New lead-freeIodoantimonatehalide semiconductor: Synthesis, Structural characterization, DFT calculations, Hirshfeld surface, Thermal behavior, vibrational and optical properties

Hybrid metal halides have captured broad interest in the lighting and display fields because of their unique electronic structures and splendid broadband emission properties. Organic chiral building blocks can control light, charge, and spin interconversion in hybrid crystalline semiconductors with metal-halide.Based on the chiral organic molecules(S)-1-phenylethylamine, we synthesized new chiral antimony halidewith zero-dimensional structure((S)-C8H12N)4Sb2I10. Atroom temperature, the title compound is crystallized in the monoclinic P21with Z = 2 and the following unit cell dimensions: a = 12.69129 (15) Å, b = 14.96770 (15) Å, c = 13.91397 (16) Å, and β = 92.2735 (11)°.The crystal structure of this compound is composed of two crystallographically independent [Sb2I10]4- unit and four (S)-1-phenylethylammonium per unit cell. The crystal packing is governed by NH....I hydrogen bonds.Intermolecular interactions seen in the grown single crystal are studied by Hirshfeld surface and 2-D fingerprint plot.In addition to study the weak interaction a visualized approach known as RDG has been carried out.The recorded infrared IR and Raman studies confirm vibrational modes for organic and inorganic groups at room temperature in the 500–4000 cm−1 and 50–4000 cm−1 frequency regions, respectively.The optimized molecular structure and vibrational frequencies were calculated by the Density Functional Theory (DFT) method using the B3LYP level employing a LANL2DZbasis set.The title compound reveals thermal stability up to 190 °C.The opticalabsorption measurement confirms the semiconductor nature with a band gap of around 3.74 eV. The frontier molecular orbital analysis HOMO-LUMOof molecule were studied.

Facile one-pot synthesis and characterization of ZnSe/HPMC nanocomposites

Herein, we report the facile synthesis of ZnSe/HPMC (Hydroxypropyl Methyl Cellulose) nanocomposites by in-situ method. The biodegradable HPMC polymer acts as capping molecule as well as polymer matrix. The optical and structural properties of ZnSe/HPMC nanocomposites were studied by optical absorption, photoluminescence (PL) spectroscopy, FTIR, XRD and TEM measurements. Size of the ZnSe nanoparticles was tuned by controlling the pH of the reaction. As prepared ZnSe nanoparticles were spherical in shape, homogeneously distributed in the polymer and XRD patterns exhibit face centred cubic phase. The present method is a novel approach for the synthesis of ZnSe nanoparticles using HPMC as a capping molecule as well as matrix to develop nanocomposite.

Self‐Assembly of MnS Shell on CdTe Nanoparticles Induced by Thermohydrolysis: Synthesis and Characterization

Herein, CdTe/MnS core/shell nanoparticles dispersed in an aqueous solution have been synthesized. The formation of MnS semiconductor shell occurs by spontaneous self‐assembly. This process is activated by thermal hydrolysis that removes the excess of thiol and releases S2− ions. In this process, Mn2+ ions on the surface of the CdTe nanoparticles bind to S2− ions to produce a fine semiconducting layer of MnS. Measurements of Raman spectroscopy, optical absorption, and electrochemical measurements are performed. The Raman spectrum shows CdTe characteristic bands at 141 and 163 cm−1. Bands at 221 and 444 cm−1 are associated with the MnS structure. Cyclic voltammetry and differential pulse voltammetry are used to estimate the electrochemical gap at ≈2.47 eV. Absorption optical measurements show tree absorption bands. A broad band between 460 and 520 nm is associated with the first transition in CdTe nanoparticle. The absorption spectrum reveals an optical gap in the range of 2.41–2.33 eV for all the refluxed samples. These values are consistent with those obtained with the electrochemical measurements. The results evidence the formation of a core–shell semiconducting nanostructure made of CdTe nanoparticles coated with a spontaneously self‐assembled thin layer of MnS nanoparticles.

Self-assembled tin(IV) organic-inorganic hybrids: Synthesis, spectral, structural, and Hirshfeld surface analysis of bis(thiomorpholinium) hexahalostannate(IV)

At room temperature, organic-inorganic hybrids, including bis(thiomorpholinium) hexachlorostannate(IV) hydrate (1) and bis(thiomorpholinium) hexabromostannate(IV) (2), were synthesized from thiomorpholinium chloride/bromide. The hybrids underwent characterization using, IR, elemental, NMR, TGA, DRS and PL spectroscopy, along with single-crystal X-ray diffraction (SCXRD). SCXRD confirms compounds are crystallized in a monoclinic system exhibiting centrosymmetric space groups (C2/candP21/c for (1) and (2)). The SCXRD structures of the hybrids unveiled significant H-bonded interactions between the thiomorpholinium cation and the SnCl62-/SnBr62- anions. At room temperature, optical absorption measurements revealed band gaps of 3.91 eV for (1) and 3.00 eV for (2).TGA confirmed the proposed formulas of the compounds.BVS calculations conducted on SnCl62- and SnBr62- anions yielded values of 4.01 and 3.94, respectively. Fingerprint plots were employed to identify and quantify the proportion of hydrogen bonding interactions.

Temperature dependence of the near infrared absorption spectrum of single-wall carbon nanotubes dispersed by sodium dodecyl sulfate in aqueous solution: experiments and molecular dynamics study.

Single-wall carbon nanotubes (SWCNT) dispersed in water with the help of sodium dodecyl sulfate (SDS) surfactants exhibit a temperature dependent near infrared (NIR) exciton spectrum. Due to their biocompatibility and NIR spectrum falling within the transparent window for biological tissue, SWCNTs hold potential for sensing temperature inside cells. Here, we seek to elucidate the mechanism responsible for this temperature dependence, focusing on changes in the water coverage of the SWCNT as the surfactant structure changes with temperature. We compare optical absorption spectra in the UV-Vis-IR range and fully atomistic molecular dynamics (MD) simulations. The observed temperature dependence of the spectra for various SWCNTs may be attributed to changes in the dielectric environment and its impact on excitons. MD simulations reveal that the adsorbed SDS molecules effectively shield the SWCNT, with ~ 70% of water molecules removed from the first two adlayers; this coverage shows a modest temperature dependence. Although we are not able to directly demonstrate how this influences the NIR spectrum, this represents a potential pathway given the strong influence of the water environment on the excitons in SWCNTs. Optical absorption measurements were carried out in the UV-Vis-NIR range using a Varian Cary 5000 spectrophotometer in a temperature-controlled environment. PeakFit™ v. 4.06 was used as peak-fitting program in the spectral range 900-1400nm (890-1380meV) as a function of the temperature. Fully atomistic molecular dynamics simulations were conducted using the NAMD2 package. The CHARMM force field comprising two-body bond stretching, three-body angle deformation, four-body dihedral angle deformation, and nonbonded interactions (electrostatic and Lennard-Jones 6-16 potentials) was employed.

Exploring the structural, optical and photoluminescence of novel terbium-doped barium borosilicate glasses for high-performance technologies

The production process involved the use of the melt-quenching approach to produce a series of barium borosilicate glasses with the specific chemical formula 55B2O3+(26-x)BaO+12SiO2+7Na2O + xTb4O7, where x = 0, 0.5, 1, 2, and 3 mol%. X-ray diffraction (XRD), Raman spectroscopy, optical absorption, and photoluminescence spectra measurement were used to examine the prepared samples. X-ray diffraction revealed the non-crystalline character of the assembled samples. The Raman spectroscopy revealed that the incorporation of Tb4O7 into borosilicate glasses induced alterations in their structure. As the doping of Tb3+ ions increases, the density and molar volume of the glasses under investigation increase. Furthermore, the ion concentration and field strength increase while the polaron radius and inter-ionic distance decrease. The glass optical absorption spectra showed five peaks in the wavelength range from 300 nm to 2000 nm: 5L10, 5D3, 5D4, 7F(0, 1, 2), and 7F3, attributed to Tb3+ ion electronic transitions. In addition, optical parameters like optical energy gap, Urbach energy, refractive index, molar refractive index, reflection loss, electronic polarizability, and optical transmission coefficient were computed. Terbium-doped borosilicate glasses had a decreased optical energy gap and an improved refractive index. Photoluminescence spectra were excited at 325 nm and showed five peaks in the range of 400–750 nm. Photoluminescence (PL) emission spectra exhibit distinct peaks in the visible range.

Impact of electronic correlation on strong laser-induced bound-state transitions.

Electron correlation (EC) plays a crucial role in all multi-electron systems and dynamic processes. In this work, we focus on strong laser-induced bound-bound transitions (BBT), which are fundamental to optical absorption measurements. We use the helium atom, the simplest two-electron system, as our test case, utilizing the ab initio code package HeTDSE. We examined the bound state energy levels, transition dipole moments (TDMs), and the dynamics of strong laser-induced BBT, both with and without considering EC. Our results indicate that EC significantly impacts the energy levels of the bound states and the TDMs. These effects collectively influence the transition dynamics of the excited states. Although EC does not alter the quantum transition pathways between resonance states, it generally increases the probability of resonance transitions in most cases. Our findings provide a quantitative description of EC in laser-induced BBT.

Structural, optical, and electrical properties of multi-component P-type oxide-semiconductor Cu-Mn-Sn-O thin films

P-type oxide semiconductors have attracted significant attention as conducting channel layers due to their wide applications in electronic devices. In this study, multi-component oxide-semiconductor Cu1–2xMnxSnxO thin films with x = 0.05, 0.10, 0.15, 0.20, 0.25, 0.30, and 0.33 were prepared on glass substrates using a solution process accompanied by a spin-coating technique. A phase transition between the cupric oxide monoclinic structure and the rock salt structure was observed with increasing concentrations of Mn and Sn, while the concentration of Cu simultaneously decreased in the precursors. The crystallite size decreased throughout the samples, reaching a minimum value of 9.8 nm at an equimolar ratio. Scanning electron microscopy further confirmed this downward trend and indicated an improvement in the quality of the film surfaces. According to the optical absorption measurements, the bandgap energy ranged from 2.68 to 3.44 eV. Interestingly, the sheet resistance of Cu1–2xMnxSnxO films dropped sharply from 5.24 kΩ/sq for CuO to 0.034 kΩ/sq for the film with a molar ratio of Cu:Mn:Sn being 34:33:33.

Electronic states near surfaces and interfaces of β-Ga2O3 and κ-Ga2O3 epilayers investigated by surface photovoltage spectroscopy, photoconductivity and optical absorption

Transient surface photovoltage (SPV) spectroscopy, optical absorption, and photoconductivity (PC) were applied to study electronic transitions in (-201) β-Ga2O3 and (001) κ-Ga2O3 epitaxial layers on c-plane sapphire substrates. SPV signals were distinguished for charge separation near the surface and near the layer/substrate interface. The bandgaps of β-Ga2O3 and κ-Ga2O3 epitaxial layers were found to be, respectively, about 4.75 and 4.79 eV from optical absorption measurements, about 4.8 and 4.9 eV from PC, and 4.65 and 4.9 (near the surface) from SPV measurements. Near the κ-Ga2O3 layer/substrate interface SPV instead gives a value of 4.75 eV, possibly related to the presence of an interlayer. Defect-related transitions with onset energies at about 4.5, 4.1, and 3.5 eV were observed along the whole β-Ga2O3 layer cross-section. In contrast, defects related to different transitions were differently distributed in κ-Ga2O3 epitaxial layers: transitions setting on at about 4.3 eV originate from defects uniformly distributed across the layer, while transitions starting at 2.4 eV and 1.7 eV were respectively connected with defects located near the surface or near the layer/substrate interface. The PC measurements at photo-excitation energy above the bandgap indicated that defect densities and recombination losses were much larger in κ-Ga2O3 than in β-Ga2O3.