Structural,optical, and electrical properties of Cu2SnS3 thin films produced by sol gel method

Physics of the Solid State - The structural, optical, and electrical properties of p-type Cu2SnS3 thin films produced by the deposition of a dimethylsulfoxide-based sol gel solution using the...     

Optical properties of thin Cu<Subscript>2</Subscript>ZnSnS<Subscript>4</Subscript>, films produced by RF magnetron sputtering

Optical properties of thin Cu₂ZnSnS₄ films produced by RF magnetron sputtering of preliminarily synthesized material are studied. Transmission and reflection coefficients are studied in a range from 0.4 to 26 μm. The optical band-gap width depending on substrate temperature is estimated; in optimal modes, it is equal to 1.47 eV. The study of electrical properties shows that Cu₂ZnSnS₄ possesses low charge-carrier mobility, μ = 1.9 cm²/(V s), at room temperature and hole concentration р = 5 × 10¹⁸ cm^–3. Electron microscopy shows that the film possesses a polycrystalline structure with a crystallite size on the order of 100 nm.     

Specific features of the optical and electrical properties of polycrystalline CdTe films grown by the thermal evaporation method

The results of studying the physical properties of thin CdTe films obtained by the thermal evaporation method have been presented. The optical constants and the band gap of the films under study have been determined (E _g = 1.46 eV). It has been established based on the investigation of optical properties and the Raman spectrum of the films that they possess high structural quality. The activation energy of the electrical conductivity of CdTe films has been determined: E _a = 0.039 eV. The measured spectral dependences of the impedance of CdTe thin films are characteristic of the inhomogeneous medium with two time constants: τ_gb = R _gb C _gb = 1/ω_gb = 1.62 × 10^?3 s and τ_g = R _g C _g = 1/ω_g = 9.1 × 10^?7 s for grain boundaries and grains, respectively.     

Structural and photoluminescent properties of TiN thin films

Structural and photoluminescent properties of TiN thin films deposited by dc reactive magnetron sputtering are studied. It is found that TiN thin films are polycrystalline with a grain size of ～15 nm and have a NaCl-type cubic crystal structure with a lattice constant of 0.42 nm. The TiN films under study exhibit photoluminescence in the spectral range h _ν ≈ 2.1–3.4 eV at 300 K.     

Optical properties and mechanisms of current flow in Cu<Subscript>2</Subscript>ZnSnS<Subscript>4</Subscript> films prepared by spray pyrolysis

Thin films Cu₂ZnSnS₄ (up to 0.9 μm thick) with p-type conductivity and band gap E_g = 1.54 eV have been prepared by the spray pyrolysis of 0.1 M aqueous solutions of the salts CuCl₂ · 2H₂O, ZnCl₂ · 2H₂O, SnCl₄ · 5H₂O, and (NH₂)₂CS at a temperature T_S = 290°C. The electrophysical properties of the films have been analyzed using the model for polycrystalline materials with electrically active grain boundaries. The energy and geometric parameters of the grain boundaries have been determined as follows: the height of the barriers is E_b ≈ 0.045–0.048 eV, and the thickness of the depletion region is δ ≈ 3.25 nm. The effective concentrations of charge carriers p₀ = 3.16 × 10¹⁸ cm^–3 and their mobilities in crystallites μ_p = 85 cm²/(V s) have been found using the technique for determining the kinetic parameters from the absorption spectra of thin films at a photon energy hν ≈ E_g. The density of states at grain boundaries N_t = 9.57 × 10¹¹ cm^–2 has been estimated.     

Molybdenum oxide thin films in CdTe‐based electronic and optoelectronic devices

This paper reports on the both possible applications of molybdenum oxide (MoO_x) thin films in combination with hole or electron conducting CdTe. The high quality ohmic contancts and strongly rectifying photodiodes were prepared by the DC magnetron sputtering of MoO_x thin films onto freshly cleaved p‐ and n‐type CdTe single crystal substrates. The analysis of DC and AC electrical properties of the MoO_x/ p‐CdTe ohmic contact was carried out. The dominating current transport mechanisms through the MoO_x/p‐CdTe heterojunction at forward and reverse bias were determined. The unoptimized heterojunction photodiode showed promising rectifying and photoelectrical characteristics for practical application in the photoconductive mode. (© 2016 WILEY‐VCH Verlag GmbH &Co. KGaA, Weinheim)     

Electrical and Optical Properties of Cu<Subscript>2</Subscript>Zn(Fe,Mn)SnS<Subscript>4</Subscript> Films Prepared by Spray Pyrolysis

We have analyzed the electrical and optical properties of Cu₂ZnSnS₄, Cu₂FeSnS₄, and Cu₂MnSnS₄ films with the p-type electrical conductivity, which were prepared by spray pyrolysis at temperature TS = 290°C using 0.1 M aqueous solutions of salts CuCl₂ · 2H₂O, ZnCl₂ · 2H₂O, MnCl₂ · 2H₂O, FeCl₃ · 6H₂O, SnCl₄ · 5H₂O, and (NH₂)CS. The energy parameters have been determined from analyzing the electrophysical properties of the films using the model of energy barriers at grain boundaries in polycrystalline materials, and the thickness of intercrystallite boundaries has been estimated. The extent of the influence of the hole concentration p₀ in the bulk of crystallites and height E _b of the energy barriers between grains on the electrical conductivity has been determined. The optical bandgap width for thin Cu₂Zn(Fe,Mn)SnS₄ films has been calculated based on analyzing the spectral dependences of the absorption coefficient.     

Kinetic properties of TiN thin films prepared by reactive magnetron sputtering

Results of investigations of kinetic properties of TiN thin films prepared by dc reactive magnetron sputtering are presented. It is established that the TiN thin films are polycrystalline and possess semiconductor n-type conduction. The carrier concentration is ～10²² cm^?3, while electron scattering occurs at ionized titanium atoms.     

Structural and optical properties of Cu2ZnSn(S,Se)4 films obtained by magnetron sputtering of a Cu2ZnSn alloy target

Results of the study of structural and optical properties of Cu₂ZnSn(S,Se)₄ thin films obtained by sulfitation (selenization) of Cu₂ZnSn films which were sputtered by target direct current magnetron sputtering using a stoichiometric Cu₂ZnSn (99.99%) target are presented. It has been found that Cu₂ZnSn(S,Se)₄ thin films are polycrystalline with a grain size of ~60 nm. The optical bandgap of Cu₂ZnSnS₄ (E ^op _g = 1.65 eV) and Cu₂ZnSnSe₄ (R ^op _g = 1.2 eV) thin films have been determined.

     

Low-temperature spray-pyrolysis of FeS2 films and their electrical and optical properties

Iron disulfide (FeS₂) films with a wide range of electrical resistivities 100 Ω cm ? ρ ? 800 kΩ cm, a high adhesion to the substrate, and a resistance to aggressive media have been prepared by the spray pyrolysis of aqueous solutions of the salts FeCl₃ · 6H₂O and (NH₂)₂CS at low temperatures in the range 250°C ? T _S ? 400°C. It has been found that the FeS₂ films have a high transmittance T ≈ 60–70% and are characterized by a sharp transmission edge. It has been shown that the optical band gap for direct (E _g ^op = 2.19–2.78 eV) and indirect (E _g ^′op = 1.26–1.36 eV) optical transitions depends on the conditions of film preparation.