Mn-doped Films Research Articles

Manganese-doped transparent conductive magnetic indium oxide films integrated on flexible mica substrates with high mechanical durability

Recent advances in flexible electronic devices have stimulated demands for the fabrication of multifunctional materials on highly flexible substrates. However, flexible diluted magnetic semiconductor films have been inadequately reported thus far. In this study, I grew polycrystalline manganese (Mn)-doped indium oxide (In2O3) films on flexible mica substrates at three deposition temperatures (Td) using the pulsed laser deposition method. All the investigated Mn-doped In2O3 films exhibited high optical transparency, high electrical conductivity, room-temperature ferromagnetism, and excellent mechanical durability. The present experimental results demonstrate that Td considerably influences the optical, electrical, and magnetic properties as well as the mechanical durability of the flexible Mn-doped In2O3 films. Based on the robustness of inorganic mica at high deposition temperatures, this detailed investigation provides a strategy for fabricating flexible diluted magnetic semiconductor films, the properties of which could be carefully optimized by widely varying the Td.

Cu2+ assisted Mn-doped perovskite nanocrystals thin films: Room-temperature synthesis and improved emission efficiencies

Mn and Cu co-doped perovskite nanocrystal (NCs) thin films with high Mn2+ doping concentration are successfully achieved by a simple one-pot method at room temperature. Structural and compositional analyses manifest that Cu2+ ions can partly replace the Pb2+ ions in the lattice structure and effectively reduce the defect concentration of 2 CsPb(Br/Cl)3 NCs. Steady-state and time-resolved photoluminescence (PL) spectroscopy were employed to characterize the effect of Cu ions doping on the luminescence properties of Mn-doped CsPb(Br/Cl)3 NCs. Mn2+ related PL quantum yields of Mn-doped CsPb(Br/Cl)3 NCs thin films with the Mn/Pb ratios of 7:1 was validly improved from ~34% to ~50% because of the incorporation of Cu2+ ions. Our work provides a low-cost synthesis for Mn-doped perovskite NCs thin films with high emission efficiency in the application of lighting, display and photodetector.

Electrical and magnetotransport properties of In0.95Mn0.05Sb film

The In0.95Mn0.05Sb film has been obtained on a Silicon substrate using a thermally evaporated technique. The structural, electrical, magnetotransport and surface magnetic interaction properties of the Mn-doped InSb film are investigated. The X-ray diffractogram shows a single-phase nanocrystalline structure in the highly oriented direction of (111). The upturn in the resistivity observed at (<35 K) low temperature is attributed to the Coulomb Blockade effect. From the resistivity measurement, the observed bandgap is 0.16 eV. At room temperature, negative magnetoresistance is observed. The weak magnetic signals at the surface are observed through magnetic force microscopy.

Thermoelectric properties of β-(Cu,Mn)2Se films with high (111) preferred orientation

Mn-doped β-Cu2Se films were prepared on a single-crystalline Si substrate with an insulating SiO2 layer using a sintered Cu–Se compound target by magnetron sputtering. The phase composition, microstructure and thermoelectric properties of deposited films were studied. The results show that the films are composed of only single β-Cu2Se phase with highly (111) referred orientation. Mn replaces Cu atom in β-Cu2Se lattice and β-(Cu,Mn)2Se solid solution forms. In the deposited β-Cu2Se films doping Mn, the atomic ratio ([Cu]+[Mn])/[Se] of Cu + Mn to Se content exceeds 2.0. The deposited β-(Cu,Mn)2Se films possess p-type conductivity characteristics. The carrier concentration decreases and the carrier mobility increases with increasing Mn content, respectively. The resistivity and Seebeck coefficient of the deposited films increase with increasing Mn content. The film with 1.94 at.% Mn possesses the highest power factor in the range of 100–400 °C and its figure of merit (ZT) reaches 0.85 at room temperature. The thermoelectric properties of the β-Cu2Se films are able to be improved by doping an appropriate amount of Mn and obtaining highly (111) preferred orientation.

Solid solubility and charge compensation/exchange mechanisms in Ga- or Mn-Doped CeO2 thin films on 3D printed biomedical titanium alloy

CeO2 films doped with 0–9 mol% Ga/Mn were fabricated by spin coating on 3D-printed Ti6Al4V, calcined at 650 °C for 2 h, and characterised by TEM, FESEM, 3D laser scanning confocal microscopy, GAXRD, and XPS. The results depend on the roles of several factors: (1) Sol-gel precursor viscosity affected pore filling and surface coverage. (2) Lattice contraction and resultant intervalence charge transfer increased the Ce3+ concentration as a minority effect. (3) Substitutional solid solubility and associated redox charge compensation controlled the defect equilibria, which highlight the majority role of this solid solubility mechanism in decreasing the Ce3+ concentration. (4) Electronegativity played a negligible role in affecting the valences but was important in initiating intervalence charge transfer. (5) Multivalence charge transfer combined electron exchanges between film matrix, dopants, and Ti substrate. The present work provides a foundation to interpret the effects of extrinsic effects from both dopant and substrate on the properties of films.

Significantly reduced leakage current density in Mn-doped BiFeO3 thin films deposited using spin coating technique

BiFeO3 (BFO) and Mn-doped BFO thin films are prepared on indium tin oxide/glass substrates using wet chemical deposition technique. The role of Mn defects (3% to 10%) on the leakage current density and other physical properties of BFO thin film devices is investigated. The X-ray diffraction patterns confirm the single-phase formation of rhombohedrally distorted BFO thin films. The scanning electron microscopy images approve uniform and crack-free film depositions, which is of great importance to the practical device applications of such materials. The oxidation states are determined by X-ray photoelectron spectroscopy (XPS). These XPS results reveal the presence of multiple valence states of Fe ions (Fe2+, Fe3+) and Mn (Mn3+, Mn4+) ions, which play a decisive role in determining the leakage current density. However, the Mn-doping at the Fe site in BFO reduces oxygen vacancies and Fe2+ states, hence suppressing the leakage current density. The leakage current density is reduced by three orders of magnitude (10−4 – 10−7) A/cm2, upon Mn-doping as clearly demonstrated by J-V characteristics. These results indicate that the primary contributors to the conduction in BFO based thin films are oxygen vacancies and the Fe2+ states in these devices.

Mn-doping-induced tunable bandgap and luminescence properties of SnO2 nanoparticles grown by SILAR method

In the present study, pure and Mn doped SnO2 thin films were grown by performing successive ionic layer adsorption and reaction (SILAR) method on the glass substrates at room temperature. The fabricated thin films have been studied to assess the influence of Mn doping on structural, morphological, and optical properties of SnO2 crystal lattice. The X-ray diffraction (XRD), Ultraviolet–visible spectrometer (UV–Vis), Energy dispersive X-ray analysis (EDAX), Scanning electron microscope (SEM), Raman, X-ray photoelectron spectroscopy (XPS), and Photoluminescence (PL) spectra measurements were conducted. After the XRD and SEM evaluations, it was found that the grown nanoparticles were in rutile type tetragonal structure of polycrystalline nature which was supported by Raman results. And, the surface morphologies were also observed to be affected from the varied concentrations of Mn doping. Besides, the EDAX evaluation confirmed the integration of Mn content next to Sn and O ions in the synthesized SnO2 nanostructures by SILAR method. The UVi-vis analysis disclosed that the absorbance of the prepared thin films had a clear inclination to increase as doping concentration intensified. In addition to that, the optical investigations also uncovered the bandgap of SnO2 nanocrystallines could be tuned from 2.61 eV to 2.00 eV by exposing them to the different levels of Mn ions. Furthermore, the Photoluminescence spectra evidently acknowledged the possibility of engineering optical characteristics by showing increased luminescent emission intensity values right after the introduction of impurities into the SnO2 lattice. The XPS results further verified the manganese and tin valences existed in the produced thin films.

Effect of temperature on carrier transport and photoconductivity of Mn-doped FeS2 thin films

Thin-film of Mn-doped iron disulfide (FeS2) has been prepared using the thermal evaporation method. This work reports the Hall measurements, temperature and light intensity-dependent photoconductivity, electrical transport mechanism, and photodetection properties of Mn-doped FeS2 thin film. The transient photoconductivity measurements of p-type Mn-doped FeS2 thin film show a consistent dependence upon temperature and light intensity. Charge transport mechanism was illustrated using different models. In region-I (303–393 ​K) deposited film followed the thermally activated transport mechanism. Nearest neighbour hopping (NNH) transport mechanism was followed by region-II (274–293 ​K), and Mott's variable range hopping (VRH) mechanism was dominant in region-III (108–273 ​K). The fabricated device resulted in higher photoconductivity due to collecting charge carriers through electrodes under light illumination. The results also revealed that Mn-doped thin film possessed good photoresponsivity (∼19 ​mA/W) as well as photo-detectivity (∼3.4 ​× ​1012 Jones) due to the occupation of localized states formed by Mn-doping. Light intensity-dependent photodetection properties suggested the potential for real-time photodetection applications.

Influence of manganese rate on structural, optical and electrochemical properties of CeO2 thin films deposited by spray pyrolysis: Supercapacitor applications

The present work aimed to investigate the electrochemical properties of ITO substrates in propylene carbonate (PC) with 0.5 mol/L lithium perchlorate (LiClO4) medium in the presence of elaborated thin films of cerium dioxide pure and doped with manganese at varying percentages. Ce1–xMnxO2 (x = 0 wt%, 2 wt%, 4 wt% and 6 wt%) were successfully deposited by the spray pyrolysis (SP) technique on the glass substrate and ITO at 450 °C. The effects of manganese (Mn) doped thin films Ce1–xMnxO2 were studied and investigated by using different analyses namely X-ray diffraction (XRD) analysis, Raman spectroscopy method, UV–Vis spectrophotometer technique, atomic force microscopy (AFM) analysis and electrochemical properties. XRD data obtained present a polycrystalline with a face-centred cubic structure of fluorite type. Raman results of undoped and Mn doped thin films show two peaks at 465 and 600 cm−1, due to the formation of extrinsic oxygen vacancies by the incorporation of Mn into Ce1–xMnxO2 matrix. Energy dispersive spectroscopy (EDS) data show the presence of Ce, O, and Mn elements in the elaborated films. The AFM results reveal that the surface roughness decreases with increasing Mn rate. Further, band gap energy of thin films decreases with increasing in Mn rate due to the formation of defect state between valence and conduction band. The storage capacity of the elaborated Ce1–xMnxO2/ITO/PC + LiClO4 electrode reaches a maximum of 1.997 mF in the presence of 6 wt% of Mn.

Tunable structural, morphological and optical properties of undoped, Mn, Ni and Ag-doped CuInS2 thin films prepared by AACVD

The preparation of high-quality copper indium sulphide, CuInS2 photo-absorber material with tunable properties for efficient, low-cost, thin film solar cells using scalable methods remains a challenge. In order to address this, high quality off-stoichiometric undoped and Mn, Ni and Ag-doped CuInS2 (CIS) thin films have been deposited onto glass substrates by aerosol-assisted chemical vapour deposition (AACVD) using metal diethyldithiocarbamate precursors at temperatures of 350, 400 and 450 °C. Data from powder X-ray diffraction (p-XRD), Raman spectroscopy and scanning electron microscopy-energy dispersive X-ray spectroscopy (SEM-EDS) suggest a correlation of morphology and composition of tetragonal phase (chalcopyrite and copper-gold-type) sulphur-deficient microcrystalline CIS thin films. For undoped thin films, near-infrared optical absorption and emission with tunable band gap between 1.32 and 1.42 eV are likely associated with donor-acceptor pairs involving deep or shallow electronic states such as sulphur vacancies (VS••), indium-copper anti-sites (InCu••) and indium interstitials (Ini•••) as donors and copper vacancies (VCu′) as acceptors. Whilst Mn-doped thin films exhibit minimal tunable properties, Ni and Ag-doped films exhibit tunable morphology, composition and near-infrared absorption for small dopant content. Though further studies are required to explore the defect chemistry, these results show the utility of AACVD in tuning structural, morphological and optical properties of undoped, Mn, Ni and Ag-doped CIS thin films.

Study the structural properties of Mn-doped CuO thin films prepared by chemical spray pyrolysis technique

In this paper CuO thin films were prepared by chemical spray pyrolysis method with different dopant concentration of Mn (0, 0.03, 0.05, 0.07 and 0.09)% deposited on glass substrates at (400) °C, and thickness of (450 ± 50) nm. Structural properties of (CuO: Mn) Thin films have been studied by X-ray diffraction (XRD), Field-Emission Scanning Electron Microscope (FESEM) and Atomic Force Microscope (AFM). The results showed that the structure of CuO thin films was of crystalline monoclinic and the (1-11) plane was the preferred orientation. In sewing study, the mean grain size decreased as the dopant (Mn) concentration increased in the (nm) range. Structural Parameters including dislocation intensity (δ), and the crystal number per unit area (No) was Counts too. Results of Atomic Force Microscopy (AFM) showed that the surface roughness and the root mean square roughness (RMS) decreased with the increasing of (Mn) dopant.

Optimization of chemically sprayed ZnS films by Mn doping

In this study, undoped and Mn doped ZnS films were grown on microscope glass substrates at substrate temperature of 400 ± 5 °C by using a low cost Ultrasonic Spray Pyrolysis technique, and the effect of Mn doping on some physical properties of ZnS films was investigated. Structural, optical, electrical and morphological properties of all films were analyzed using X-ray diffractometer (XRD), UV–Vis spectrophotometer, two-probe technique and atomic force microscope (AFM), respectively. X-ray diffraction studies showed that all films were formed in ZnS hexagonal structure and the crystallization levels of the films were relatively improved due to the increase in the Mn doping ratio, especially for 4% doped films. It was determined that the average transmittance value of undoped ZnS film in the visible region is 38% and this value increases to 60% for the sample doped by Mn at the highest rate (12%). The band gap values of the films were calculated using the Tauc equation and determined to be between 3.82 and 3.94 eV. Electrical resistivity values of the films decreased significantly due to the Mn doping. Mn doping also caused ZnS films to have uniform surface morphologies consisting of noticeable particle formations. Figure of merit calculations showed that Mn doping has a favorable effect on ZnS films and ZnS:Mn (12%) films may be promising materials for applications such as photovoltaic solar cells and optoelectronic devices.

In situ preparation of Mn-doped perovskite nanocrystalline films and application to white light emitting devices

Mn-doped perovskite nanocrystals have promised new optoelectronic applications due to their unique material properties. In the present study, Mn-doped perovskite nanocrystalline films were prepared in situ in a polymer matrix. The Mn-doped perovskite nanocrystals (PNCs) had good crystallinity and uniform size/spatial distributions in the polymer film. Bright dual-color emission and the long lifetime of the excited state of the dopant were observed from the host exciton and the Mn2+ dopant, respectively. Furthermore, magnetism was observed in the optimal Mn2+ concentration, implying that magnetic coupling was achieved in the Mn-doped perovskite lattice. The Mn-doped perovskite films also showed superior stability against moisture. To demonstrate the practicality of this composite film, a white light emitting device was fabricated by combining a single composite film with a blue light emitting diode; the device showed a high-quality white light emission, and the Commission Internationale De L'Eclairage (CIE) chromaticity coordinate of the white light emitting diode (WLED) (0.361, 0.326) was close to the optimal white color index. In this single-layer WLED, self-absorption among the luminous multilayers in traditional white light emitting diodes can be avoided. The study findings revealed that Mn-doped perovskite nanocrystalline films have many exciting properties, which bodes well for the fundamental study and design of high-performance optoelectronic devices.

Induced slim ferroelectric hysteresis loops and enhanced energy-storage properties of Mn-doped (Pb0·93La0.07)(Zr0·82Ti0.18)O3 anti-ferroelectric thick films by aerosol deposition

In this study, the high ferroelectric hysteresis loss of (Pb0·93La0.07)(Zr0·82Ti0.18)O3 (PLZT 7/82/18) antiferroelectric (AFE) ceramics was reduced by employing a combinatorial approach of Mn acceptor doping followed by thick film fabrication via an aerosol deposition (AD) process. The grains of the as-deposited PLZT 7/82/18 AFE AD thick films were grown by thermal annealing at 550 °C to enhance their electrical properties. Investigation of the electrical properties revealed that Mn-doping results in improved dielectric and ferroelectric properties, increased dielectric breakdown strength (DBS), and energy-storage properties. The Mn-doped PLZT AFE AD films possess a frequency-independent high dielectric constant (εr ≈ 660) with low dielectric loss (tan δ ≈ 0.0146), making them suitable candidates for storage capacitor applications. The bipolar and unipolar polarization vs. electric field (P-E) hysteresis loops of PLZT 7/82/18 AFE AD thick films were found to be slimmer than those of their bulk form (double hysteresis) with significantly reduced ferroelectric hysteresis loss, which is attributed to the AD-induced mixed grain structure. The Mn-doped PLZT 7/82/18 AFE AD thick films exhibited a low remnant polarization (Pr ≈ 9.22 μC/cm2) at a high applied electric field (~2750 kV/cm). The energy-storage density and energy efficiency of the Mn-doped PLZT AFE AD thick films were calculated from unipolar P-E hysteresis loops and found to be ~38.33 J/cm3 and ~74%, respectively.

Application of ZnGa₂O₄:Mn Down-Conversion Layer to Increase the Energy-Conversion Efficiency of Perovskite Solar Cells.

The perovskite solar cell is capable of energy conversion in a wide range of wavelengths, from 300 nm to 800 nm, which includes the entire visible region and portions of the ultraviolet and infrared regions. To increase light transmittance of perovskite solar cells and reduce manufacturing cost of perovskite solar cells, soda-lime glass and transparent conducting oxides, such as indium tin oxide and fluorine-doped tin oxide are mainly used as substrates and light-transmitting electrodes, respectively. However, it is evident from the transmittance of soda-lime glass and transparent conductive oxides measured via UV-Vis spectrometry that they absorb all light near and below 310 nm. In this study, a transparent Mn-doped ZnGa₂O₄ film was fabricated on the incident surface of perovskite solar cells to obtain additional light energy by down-converting 300 nm UV light to 510 nm visible light. We confirmed the improvement of power efficiency by applying a ZnGa₂O₄:Mn down-conversion layer to perovskite solar cells.

Nanostructured Mn-doped CeO2 thin films with enhanced electrochemical properties for pseudocapacitive applications

Cerium oxides with variable oxidation states, high interfacial charge transfer rate have demonstrated to be a potential pseudocapacitive material. In this paper, we present the structural and electrochemical properties of undoped and Mn-doped CeO2synthesized using successive ionic layer adsorption and reaction(SILAR) method. The structural results as obtained from x-ray diffraction (XRD) confirmed the cubic fluorite structure of CeO2 which was unaltered despite the doping concentration. However, a tensile strain of ~2.3% was observed due to ionic radii difference. The topography showed a porous network of nanograins, accounting for strong redox interfacial charge transfer. A specific capacitance of 690 Fg−1 was obtained for 5 wt% Mn-doped CeO2, from cyclic voltammetry curve at a scan rate of 10 mV/s. This value is considerably higher than what was obtained for the undoped ceria, indicating that doping with Mn improved the electrochemical performance of the ceria films.

Prominent ferroelectric properties in Mn-doped BiFeO3 spin-coated thin films

BiFe1-xMnxO3 (BFMO, x = 0–0.05) thin films were successfully deposited onto fluorine-doped tin oxide (FTO)/glass substrates via sol–gel technique. According to results obtained from XRD, Raman spectroscopy, SEM, and energy-dispersive EDS, it was found that films have rhomboid perovskite structure and Mn ions were successfully and uniformly incorporated into BiFeO3 (BFO) films. Doping process was accompanied by the reduction in grain size. From XPS pattern, it was found that both Fe2+ concentration and oxygen vacancies are reduced as a result of Mn doping. Compared with pure BFO samples, ferroelectric, dielectric, and optical properties of BFMO films are noticeably enhanced. BiFe0.96Mn0.04O3 film exhibited excellent remnant polarization (2Pr of 312 μC/cm2) accompanied by a low leakage current. Underlying mechanism can be explained in terms of Mn doping-induced structural transition, reduction in grain size, and oxygen vacancies. Additionally, increased bandgap (Eg = 2.68 eV) was obtained in BiFe0.98Mn0.02O3 film compared with BFO film (Eg = 2.58 eV). This work demonstrates remarkable effect of Mn doping on BFO, indicating that BFMO is promising candidate for ferroelectric photovoltaic device applications.

Structural, Optical and Morphological Properties Cadmium Sulfide Thin Films Prepared by Hydrothermal Method

In this research, pure and 4%, Mn-doped thin films of cadmium sulfide (CdS) were synthesized using a 2-hour hydrothermal process. The effect of adding the dopant concentration on thesamples' structural, morphological, and optical characteristics were investigated. The ultraviolet-visible-NIR spectrophotometer was used to investigate the optical properties. UV-Vis experiments lowered the optical bandgap with an add Mn percentage. Their optical bandgap was 2.38 eV for undoped thin films and 1.81 eV for 4% doped Mn-CdS thin films. UV-Vis spectroscopy data are in agreement with PL. FE-SEM imaging revealed morphological changes caused by the inclusion of Mn in CdS thin films. FE-SEM displays images of undopedCdS,which appear to be Nanoparticles. Morphology of the thin films has shown that the average grain size increases by the agglomeration of Nano-grains, which become clusters of particles after Mn+2incorporation. In addition, The XRD pattern revealed that prepared samples H (002)/C (111) as hexagonal and cube phases have a preferential orientation. The increase in the main diffraction peak (002) intensity with increasing Mn concentration revealed the substitution of Mn+2 with Cd+2 in the lattice. The crystallite size increased from10.74 to 11.67 nm with an Mn percentage.

Bandgap tuning in ZnO thin films and enhanced n-type properties through Mn doping synthesized by a simple spray pyrolysis

Undoped and manganese (Mn)-doped zinc oxide (ZnO) thin films have been deposited onto glass substrates at 300[Formula: see text]C using a low cost spray pyrolysis technique. Structural, optical and electrical properties of the as-deposited films have been investigated. Scanning electron microscopy images show the existence of clusters with well-defined nucleation centers consisting of highly dense ganglia-like fibers over a large area around the nucleation center. Chemical compositions of the ZnO and Mn-doped ZnO thin films are studied by using energy dispersive X-ray (EDX) analysis. X-ray diffraction spectra depict that the films have polycrystalline wurtzite structure. The average crystallite sizes are calculated in the range of 8–16 nm by Williamson–Hall method and found in good agreement with Scherer method. Optical transmittance of the films is about 80% in the visible region. Bandgap energy is tuned to 2.83 eV from 3.10 eV with increasing Mn doping. Electrical resistivity at room-temperature decreases significantly with increasing Mn doping as well as increasing temperature from 300–440 K. The activation energies in the temperature ranges 300–350 K and 350–440 K are found to be in the range of 0.25–0.16 eV and 0.35–0.59 eV, respectively. Hall Effect measurements show that the thin films have negative Hall co-efficient indicating [Formula: see text]-type conductivity at room-temperature. Carrier concentration is found to be of the order of 10[Formula: see text] cm[Formula: see text].

Improved crystallization, domain, and ferroelectricity by controlling lead/oxygen vacancies in Mn-doped PZT thin films

Pb(Zr0.3Ti0.7)O3-x mol% Mn (PZTM) (x = 0, 1, 2, and 3) thin films with high density and good crystallinity were obtained using a sol-gel method. Improved crystallization, domain, and ferroelectricity through controlling the lead/oxygen vacancies in Mn-doped lead zirconate titanate (PZT) thin films were investigated. Enhanced ferroelectricity and piezoelectricity were obtained in the 1 mol% Mn-doped PZT thin films. According to the Bragg equation, a small amount of Mn replaces the A-site (Pb2+) to achieve donor doping, which is conducive to the movement of domains and enhances the ferroelectric performance and piezoelectric coefficient. The pinning effect leads to reduced ferroelectric performance, which is caused by oxygen vacancies generated by Mn2+ replacing the B-site (Zr4+/Ti4+) during acceptor doping. The research results show that Mn doping is an effective method for improving the ferroelectric performance of PZT thin films.