Sn Thin Films Research Articles

Ultraviolet-Visible-Near-Infrared Broadband Photodetector Enabled by Cs2AgBiBr6: Sn/Conjugated Polymer Heterojunction.

Broadband photodetectors covering ultraviolet (UV) to near-infrared (NIR) wavelengths play an essential role in communications, imaging, and biosensing. Developing a single photodetector with a broadband optical response operating at room temperature can significantly reduce the complexity and cost of receiver systems for multispectral applications. In this work, utilizing the porous structure characteristics of Cs2AgBiBr6:Sn thin films, a self-powered detector with broad spectral response (UV-vis-NIR) was achieved by constructing an effective Cs2AgBiBr6:Sn/PDPP3T heterojunction. This photodetector possesses a broad response spectrum from 350 to 950 nm with an average detection rate exceeding 1011 Jones and maintains excellent photoelectric performance over two months. Sn2+ doping effectively reduces the bandgap of Cs2AgBiBr6, enhancing its near-infrared absorption and optimizing energy level alignment with conjugated polymer (diketopyrrolopyrrole-terthiophene, PDPP3T). More importantly, the porous structure derived from Sn doping significantly improves carrier extraction and transport under a near-infrared light response at the heterojunction interface. Utilizing its broad spectral response characteristics in the UV-vis-NIR range, a novel information transfer and encryption system employing full optical modulation has been realized within a single perovskite photodetector. This work provides a new approach to fabricating lead-free double perovskite broadband photodetectors with potential applications in photonic devices.

Reduced Persistent Photoconductivity in Successive Ionic Layer Adsorption and Reaction‐Deposited ZnO:Sn Thin Films

Device‐quality Sn‐doped ZnO thin films are obtained from a simple and cost‐effective successive ionic layer adsorption and reaction method with doping concentrations of 1, 3, 5, and 7 mol%. The influence of doping on the structural, morphological, and optoelectronic properties is studied. All the samples show a hexagonal wurtzite structure with planes that reorient themselves upon doping. Morphological studies reveal sharp cone‐like structures branching out to become florets upon doping, resulting in a higher surface‐to‐volume ratio that is reflected in the photoresponse characteristics. The optical properties show a sharp absorbance edge, in the near‐UV region, for all the samples. The calculated bandgap is in the range of 3.19–3.23 eV. Photoluminescence spectra are recorded to analyze the defect states in the samples, and the native defects of ZnO are found. A remarkable increase in current is observed upon illumination indicating significant photoresponse. ZnO tends to show persistent photoconductivity wherein there is delayed decay in the photocurrent. This phenomenon is reduced significantly herein by doping with Sn atoms. The spectral response study confirms that the devices are suitable for visible‐blind, near‐UV detection.

Enhancement of optical and electrical properties of tin oxide thin films through Zr + Ag doping for photocatalytic and photovoltaic applications

Abstract In present investigation, Pure Tin (Sn), Zirconia (Zr) and Silver (Ag) doped Sn thin films are prepared by jet nebuliser spray technique and utilised for possible photovoltaic application. A simple soft chemical technique used to create Zr and Ag doped SnO2 nanocrystalline nanoparticles. As shown by the results of the XRD analysis, the nanoparticles found a tetragonal structure with P42/mnm symmetry, in accordance with the appearance of highly crystalline SnO2. The optical properties were performed, and their bandgap energies were found to be 2.8, 3.1 and 3.2 eV, respectively. Particles of prepared SnO2 were analysed using FT-IR and XRD spectroscopy, which confirmed the presence of Zr and Ag. The photocatalytic performance of Sn–Zr–Ag NPs was examined by degradation of cationic Safranin dye under sunlight radiations with an interval of 15 min up to 90 min. UV–Vis spectrum analysis and a pseudo-first-order kinetics model were used to study nano catalytic dye degradation. High photocatalytic activities were observed after Zr and Ag doping, which may be enhanced further by adding H2O2. The surface characteristics of the prepared thin films are evaluated by AFM analysis. The electrochemical behaviour and photovoltaic properties are evaluated by EIS and IV characteristic studies.

Control of NLO and photocatalysis properties based on the use of Sn-doped ZnO thin films for optoelectronics applications

Thin films of zinc oxide (ZnO) have unique properties that make them suitable for various applications. In this study, we used a spray pyrolysis process to develop undoped ZnO and ZnO doped with Sn thin films on a glass substrate. We aimed to investigate the effect of Sn concentration on the optical, nonlinear optical, and structural properties of ZnO:Sn thin films. X-ray diffraction analysis revealed that all the deposited ZnO thin films exhibit polycrystalline hexagonal structures well-oriented along the c-axis. The obtained films were transparent in the visible range, with a transmittance between 70% and 80%. The optical energy bandgap values for the films varied from 3.16 eV to 3.29 eV. We also determined the second- and third-order nonlinear susceptibilities, which decreased with increasing Sn concentration. We investigated the photocatalytic activity of the ZnO-doped Sn thin films using methylene blue dye under visible light. Sn doping enhanced the photocatalytic activity of ZnO thin films, with constant rate values of 0.00046 and 0.00074 min[Formula: see text] for ZnO and ZnO:Sn thin films, respectively.

Transport characterization of magnetic phase transition in Mn<sub>3</sub>Sn thin films

In recent years, topological antiferromagnetic material with hexagonal Kagome structure has attracted great research interest due to its unique properties. Although its net magnetic moment is close to zero, the topological antiferromagnet exhibits the strong magnetoelectric, the magneto-optical, and the magnetothermal effect, with a strength comparable to that of ferromagnetic material, which makes it highly valuable for various applications. After several years of extensive studies, it has been realized that most of the unique properties of topological antiferromagnet are actually closely related to its magnetic structure. However, it has been found that the magnetic structure of the material is highly sensitive to its chemical composition and growth condition. Therefore, it is crucial to develop a universal and simple method of measuring the magnetic structure and determining the magnetic phase transition of hexagonal Kagome topological antiferromagnetic material, which can severe as a good supplement for the current high-energy neutron diffraction approach that is not accessible for ordinary laboratories. In this study, we have successfully prepared high-quality (<inline-formula><tex-math id="M3">\begin{document}$ 11\bar{2}0 $\end{document}</tex-math><alternatives><graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="6-20231766_M3.jpg"/><graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="6-20231766_M3.png"/></alternatives></inline-formula>)-oriented hexagonal Kagome antiferromagnetic Mn<sub>3</sub>Sn thin films on (<inline-formula><tex-math id="M4">\begin{document}$1 \bar{1} 02$\end{document}</tex-math><alternatives><graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="6-20231766_M4.jpg"/><graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="6-20231766_M4.png"/></alternatives></inline-formula>)-oriented Al<sub>2</sub>O<sub>3</sub> single crystal substrates by using the pulsed laser deposition method. After systematically measuring how the magnetic and transport properties of the Mn<sub>3</sub>Sn thin film change with temperature, it is found that its magnetization curve, Hall resistivity curve, and magnetoresistance curve exhibit certain anomalous features at some or all of its three magnetic phase transition temperatures. These features can serve as good evidences of magnetic phase transitions in this hexagonal Kagome antiferromagnetic Mn<sub>3</sub>Sn thin film, or even could be used to measure the temperatures of these magnetic phase transitions. Our work contributes to the further advancement of the application of hexagonal Kagome topological antiferromagnetic materials to spin electronic devices.

Thermal annealing of DC sputtered Nb3Sn and V3Si thin films for superconducting radio-frequency cavities

Nb 3 Sn and V3Si thin films are promising candidates for the next generation of superconducting radio-frequency (SRF) cavities. However, sputtered films often suffer from stoichiometry and strain issues. This exploratory study investigates the structural and chemical effects of thermal annealing, both in−situ and post-sputtering, on DC-sputtered Nb3Sn and V3Si films with varying thicknesses, deposited on Nb or Cu substrates. Building upon our initial studies [Howard et al., Proceedings of the SRF’21, East Lansing, MI (JACoW, 2021), p. 82.], we provide fundamental insights into recrystallization, phase changes, and the issues of stoichiometry and strain. Through annealing at 950 °C, we have successfully enabled the recrystallization of 100 nm thin Nb3Sn films on Nb substrates, yielding stoichiometric and strain-free grains. For 2 μm thick films, elevated annealing temperatures led to the removal of internal strain and a slight increase in grain size. Moreover, annealing enabled a phase transformation from an unstable to a stable structure in V3Si films, while we observed significant Sn loss in 2 μm thick Nb3Sn films after high-temperature annealing. Similarly, annealing films atop Cu substrates resulted in notable Sn and Si loss due to the generation of Cu–Sn and Cu–Si phases, followed by evaporation. These results encourage us to refine our process to obtain high-quality sputtered films for SRF use.

Role of a capping layer on the crystalline structure of Sn thin films grown at cryogenic temperatures on InSb substrates

Metal deposition with cryogenic cooling is a common technique in the condensed matter community for producing ultra-thin epitaxial superconducting layers on semiconductors. However, a significant challenge arises when these films return to room temperature, as they tend to undergo dewetting. This issue can be mitigated by capping the films with an amorphous layer. In this study, we investigate the influence of different in situ fabricated caps on the structural characteristics of Sn thin films deposited at 80 K on InSb substrates. Regardless of the type of capping, we consistently observe that the films remain smooth upon returning to room temperature and exhibit epitaxy on InSb in the cubic Sn (α-Sn) phase. Notably, we identify a correlation between alumina capping using an electron beam evaporator and an increased presence of tetragonal Sn (β-Sn) grains. This suggests that heating from the alumina source may induce a partial phase transition in the Sn layer. The existence of the β-Sn phase induces superconducting behavior of the films by percolation effect. This study highlights the potential for tailoring the structural properties of cryogenic Sn thin films through in situ capping. This development opens avenues for precise control in the production of superconducting Sn films, facilitating their integration into quantum computing platforms.

Laser-induced alloy nanoparticles: Au–Sn thin film morphology influence on the dewetting process

In this paper, the impact of thin Au–Sn layers morphology on the formation of laser-induced alloy nanoparticles (ANPs) is investigated. Also, the changes in composition observed over time in thin films are analysed. The influence of deposition rate and elemental composition was studied. The tests were performed on five sets of samples of varying atomic ratios of Au–Sn and film thickness, for which the optical parameters were measured with the spectroscopic ellipsometry technique (SE). The samples were dewetted with a nanosecond Yb:glass fibre laser. All fabricated surfaces were analysed using scanning electron microscopy (SEM). Moreover, the chemical composition of obtained structures was analysed using X-ray photoelectron spectroscopy (XPS) and transmission electron microscopy (TEM).

Three-Dimensional Reconstruction of Nb3Sn Films by Focused Ion Beam Cross Sectional Microscopy

Niobium has been the material of choice for SRF cavities for several decades due to its formability and superconducting properties. The accelerating gradient of niobium cavities is, however, rapidly approaching a theoretical limit. To achieve higher accelerating gradients a new material is needed that can sustain high fields. Nb <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sub> Sn is a promising competitor with a higher superconducting transition temperature and a higher critical field than pure niobium. However, Nb <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sub> Sn is very brittle and cannot be formed readily into a cavity. The main method for creating Nb <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sub> Sn cavities is to form a Nb <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sub> Sn film into a niobium surface using a tin vapor-diffusion method. This technique creates a microcrystalline Nb <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sub> Sn thin film on the inner surface of the cavity. Tin depleted regions are known to form in the film during this process. Previous studies have analyzed these regions using transmission electron microscopy on cross-sectional lamellae prepared by focused ion beam/scanning electron microscope (FIB/SEM). This method does not provide any three-dimensional (3-D) information about the distribution of tin-deficient regions. In this study we employ a focused ion beam tomographic technique to analyze the 3-D structure of the film. Electron dispersive X-ray spectroscopy is used to image the tin concentration of the film in 3-D. Tin-deficient regions are discovered close to the surface of the Nb <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sub> Sn film.

GROWTH AND PROPERTIES OF SPIN-COATED TRANSPARENT SN AND AL-DOPED ZNO THIN FILMS

In this work, Zinc Oxide (ZnO) thin films doped and undoped with Sn and Al were grown on ITO substrates by the sol–gel spin coating technique, where the Sn/Zn and Al/Zn atomic ratios were, respectively, 5% and 7% in the solution. SZO and AZO structures were examined using XRD, AFM, SEM, UV–vis spectroscopy, and photoluminescence (PL) to investigate the morphology, structural, and optical characteristics. According to XRD analysis, all of the produced films have a hexagonal wurtzite structure with a polycrystalline nature oriented along the (1 0 0) direction. The crystallite size was calculated using the well-known Scherrer’s formula and found to be in the range of 23–40 nm. Scanning Electron Microscopy (SEM) results revealed that Sn and Al low doping had an impact on the morphological surface of the films. The measurements from the UV-Visible Spectrophotometer (U–Vis) showed that undoped ZnO film has a high optical transparency in the visible region (over [Formula: see text]%), and then the optical band gap of thin films was calculated. PL is observed for ZnO thin films doped and undoped with Sn and Al.

Berry curvature contributions of kagome-lattice fragments in amorphous Fe–Sn thin films

Amorphous semiconductors are widely applied to electronic and energy-conversion devices owing to their high performance and simple fabrication processes. The topological concept of the Berry curvature is generally ill-defined in amorphous solids, due to the absence of long-range crystalline order. Here, we demonstrate that the Berry curvature in the short-range crystalline order of kagome-lattice fragments effectively contributes to the anomalous electrical and magneto-thermoelectric properties in Fe–Sn amorphous films. The Fe–Sn films on glass substrates exhibit large anomalous Hall and Nernst effects comparable to those of the single crystals of topological semimetals Fe3Sn2 and Fe3Sn. With modelling, we reveal that the Berry curvature contribution in the amorphous state likely originates from randomly distributed kagome-lattice fragments. This microscopic interpretation sheds light on the topology of amorphous materials, which may lead to the realization of functional topological amorphous electronic devices.

Correlation between the optical and microstructural characteristics and surface wettability transition of In2O3:Sn/ZnO nanostructured bilayer system for self-cleaning application

In this research, in the Glass/In2O3: Sn/ZnO nanostructured bilayers system, In2O3: Sn and ZnO thin films were deposited onto glass using thermal evaporation and spray pyrolysis, respectively. The thin films were annealed at 350, 400‚ 450‚ 500‚ and 550 °C for 90 min. The primitive purpose of this study was to explain the effect of annealing temperature on the wettability, optical, microstructural, and morphological properties of the bilayers using UV–vis spectrophotometer, advanced x-ray diffraction (XDA) analysis, atomic force microscope (AFM), and scanning electron microscope (SEM). Various parameters were determined, including the transmission and reflection coefficients, optical energy band gap, extinction coefficient, refractive index, lattice strain, dislocation density, root mean square roughness, and water contact angle for the samples before UV exposure. The wettability results showed that the hydrophobicity of the In2O3: Sn/ZnO nanostructured thin films without UV radiation was improved by increasing the annealing temperature due to the increase in root mean square (RMS) roughness. Microstructural analysis indicated that increasing the annealing temperature increased crystallite size and decreased the lattice strain. The contact angles of the samples were significantly reduced, and the surface wettability of the layers changed from hydrophobic to hydrophilic after the UV treatment. Finally, the correlation between the optical, microstructural, morphological, and wettability features of the samples was determined. The effective optical band gap was observed to have a linear, inverse square, and quadratic correlation with strain, crystallite size, and dislocation density, respectively.

Nonreciprocal supercurrent in thin film of type II superconducting Sn

The nonreciprocal supercurrent, namely the superconducting diode effect, can be realized with various mechanisms. The recent study has demonstrated the superconducting diode effect on thin films under the out-of-plane magnetic field, owing to the asymmetric Bean–Livingston barrier on the edge. In this study, we investigated the nonreciprocal supercurrent in a thin film of Sn deposited on a diamond substrate. The Ginzburg-Landau parameter κ in the thin film was estimated to be 0.711 which is slightly higher than (0.707). We observed the nonreciprocal supercurrent owing to the asymmetric energy barrier for flux penetration on the edge.

Photodetecting properties on Sn-doped Bi2S3 thin film fabricated by nebulizer spray pyrolysis technique

Metal chalcogenides have recently gained intensive attention due to their tunable bandgap energy, optoelectronic characteristics, and exceptional optical absorption. Because of the potential advantage of photodetectors, photovoltaic, holographic recording systems, and field-effect transistors, bismuth tri-sulfide (Bi2S3) crystals, in particular, have attracted a lot of focus in scientific research. In this study, the low-cost nebulizer spray technique was employed to synthesize the proposed Bi2S3:Sn thin films on glass substrates, varying the Sn doping concentrations in Bi2S3 films (from 1 to 3%). The crystallites of the orthorhombic-structured polycrystalline Bi2S3 films were all oriented in the same direction (130). According to the XRD spectra, preferred orientation and crystalline quality were improved by Sn doping concentrations up to 2%, but, above 2% of the Sn doping ratio, the structural properties were decreased. With increasing Sn-doping levels, the estimated direct band gap (Eg) of the Bi2S3:Sn films decreased, reaching a low value of 2.01 eV at 2% Sn and then rising. A field emission scanning electron microscope (FESEM) was applied to determine the size and shape of the grains in prepared Sn: Bi2S3 films.The 2% Sn-doped Bi2S3 thin film may be more appropriate for high-speed optoelectronic devices due to its high responsivity (1.24 AW−1), external quantum efficiency (40%), and detectivity properties (1.83 × 1010Jones). A potential mechanism for photodetector performance in the presence of air and UV radiation was also discussed in the present work for the proposed Sn: Bi2S3 thin films.

Tin Metal Improves the Lithiation Kinetics of High-Capacity Silicon Anodes

Si-based anodes present a great promise for high energy density lithium-ion batteries. However, its commercialization is largely hindered by a grand challenge of a rapid capacity fade. Here, we demonstrate excellent cycling stability on a Si–Sn thin film electrode that outperforms pure Si or Sn counterpart under the similar conditions. Combined with the first-principles calculations, in situ transmission electron microscopy studies reveal a reduced volume expansion, increased conductivity, as well as dynamic rearrangement upon lithiation of the Si–Sn film. We attribute the improved lithiation kinetics to the formation of a conductive matrix that comprises a mosaic of nanostructured Sn, LiySn (specifically, Li7Sn2 develops around the lithiation potential of Si), and LixSi. This work provides an important advance in understanding the lithiation mechanism of Si-based anodes for next-generation lithium-ion batteries.

Local ordering in Ge/Ge–Sn semiconductor alloy core/shell nanowires revealed by extended x-ray absorption fine structure (EXAFS)

Short-range atomic order in semiconductor alloys is a relatively unexplored topic that may promote design of new materials with unexpected properties. Here, local atomic ordering is investigated in Ge–Sn alloys, a group-IV system that is attractive for its enhanced optoelectronic properties achievable via a direct gap for Sn concentrations exceeding ≈10 at. %. The substantial misfit strain imposed on Ge–Sn thin films during growth on bulk Si or Ge substrates can induce defect formation; however, misfit strain can be accommodated by growing Ge–Sn alloy films on Ge nanowires, which effectively act as elastically compliant substrates. In this work, Ge core/Ge1−xSnx (x ≈ 0.1) shell nanowires were characterized with extended x-ray absorption fine structure (EXAFS) to elucidate their local atomic environment. Simultaneous fitting of high-quality EXAFS data collected at both the Ge K-edge and the Sn K-edge reveals a large (≈ 40%) deficiency of Sn in the first coordination shell around a Sn atom relative to a random alloy, thereby providing the first direct experimental evidence of significant short-range order in this semiconductor alloy system. Comparison of path length data from the EXAFS measurements with density functional theory simulations provides alloy atomic structures consistent with this conclusion.

Decagonal Sn clathrate on d -Al-Ni-Co

Decagonal quasiperiodic ordering of Sn thin films on $d$-Al-Ni-Co is shown based on scanning tunneling microscopy (STM), low-energy electron diffraction, and density functional theory (DFT). Interestingly, the decagonal structural correlations are partially retained even up to a large film thickness of 10 nm grown at $165\ifmmode\pm\else\textpm\fi{}10\phantom{\rule{0.28em}{0ex}}\mathrm{K}$. The nucleation centers called ``Sn white flowers'' identified by STM at submonolayer thickness are recognized as valid patches of the decagonal clathrate structure with low adsorption energies of these motifs. Due to the excellent lattice matching (to within 1%) between columns of Sn dodecahedra in the clathrate structure and pentagonal motifs at the $d$-Al-Ni-Co surface, the interfacial energy favors clathrate over the competing Sn crystalline forms. DFT study of the Sn/Al-Ni-Co composite model shows good mechanical stability, as shown by the work of separation of Sn from Al-Ni-Co slab that is comparable to the clathrate self-separation energy. The relaxed surface terminations of the ${\mathrm{R}}_{2}{\mathrm{T}}_{4}$ clathrate approximant are in self-similarity correspondence with the motifs observed in the STM images from monolayer to the thickest Sn film.

The tin doping effect on the physicochemical and nonlinear optical properties of the manganese oxide (Mn3O4: Sn) thin films

Undoped and tin doped manganese oxide, Mn3-xSnxO4, (x=0, 2, and 4 at %) thin films were successfully elaborated by the chemical route defined in the spray pyrolysis technique and deposited on glass substrates at a temperature of 350 °C. The physicochemical characterization of the thin films was performed using an X-ray diffractometer (XRD) that showed a polycrystalline tetragonal structure for all thin films. Raman measurement confirmed the vibrational mode, A1g, and the XRD results with the presence of no secondary phases. Scanning electron microscopy coupled with energy dispersive X-ray spectroscopy depicted the surface morphology and the elemental composition (Mn, O, and Sn) of the elaborated thin films. Finally, the optical analysis was carried out, and it showed an increase in the average transmittance of the Mn3O4: Sn (0, 2, and 4 at %) from 57.6 % to 62.2 % for 700 nm and an increase of their optical band gap from 3.27 eV to 3.61 eV. We note also a decrease of their dispersive energy parameter Ed from 5.44 eV to 4.86 eV, of their static refractive index n0 from 2.02 to 1.86, as well as for their nonlinear optical parameters presented by the nonlinear refractive index n2 from 1.14 10-11 to 0.51 10-11 and the third order susceptibility χ3 from 6.14 10-13 esu to 2.49 10-13 esu. These values can be correlated to the poor crystallinity and the tensile strain of the Mn3O4: Sn (0, 2, and 4 at %) thin films, as well as to the high order of the optical bandgap energy and the decrease of the linear refractive index of these films. Hence, these thin films can be used as material for nonlinear optical applications.

Synthesis of relaxed Ge0.9Sn0.1/Ge by nanosecond pulsed laser melting

We present a new approach to the fabrication of fully relaxed Ge1-ySny layers on Ge with Sn concentration y up to 13 at. % The incorporation of Sn in Ge was obtained by sputtering of thin Sn films (<20 nm) directly on Ge wafers followed by pulsed laser melting in air. Microstructural analyses combining high-resolution transmission electron microscopy, atom probe tomography and nanobeam precession electron diffraction were performed to investigate the Sn distribution and the strain state down to the nanoscale. If y < 6 at. %, Ge1-ySny layers are fully substitutional and fully strained with no or very few extended defects. The formation of Sn-rich regions in correspondence of dislocations is instead observed for y > 6 at. %. However, outside these regions, Ge1-ySny layers present a very homogeneous Sn distribution, full Sn substitutionality, full strain relaxation, and excellent crystalline quality. This new approach could offer, if properly optimized, an alternative to epitaxy or ion implantation to fabricate high quality Ge1-ySny alloys, with the important add-on of the ability of the pulsed laser melting to perform spatially confined thermal processes (both laterally and in depth).

Chemical reactivity at Sn/CuO interface investigated by X-ray photoelectron spectroscopy

In situ characterization of the Sn/CuO interface has been undertaken by the technique of x-ray photoelectron spectroscopy. Thin films of Sn were deposited on CuO substrates kept at ambient temperature. The electron-beam technique was used for the deposition of the films. The photoelectron spectra of the core levels of tin and copper were found to exhibit significant differences upon comparison with the corresponding elemental and the oxide spectra. These differences are attributed to chemical reactivity between the constituents at the interface. Tin was observed to get oxidized to SnO2. The CuO was observed to get reduced to elemental copper. Thermodynamical considerations support the experimental observations. Certain thickness of the oxidized tin was observed to serve as a barrier for further oxidation of the tin overlayer. The relative percentages of tin oxide and elemental tin have been estimated by curve fitting the spectral data with two curves: one for elemental tin and the other for the oxide. The areas under the corresponding peaks were plotted as a function of the overlayer thickness. The data for the elemental tin in such a plot was fitted by a straight line. The extrapolation of this line to zero area provided the interface width (thickness of the SnO2 present at the interface). The width has also been determined for annealing temperatures of 100, 200, 300, 400, and 500 °C. The high temperature spectral data show interdiffusion of tin and CuO. Beyond 200 °C, the interface width was found to vary linearly with the annealing temperature.