Optical properties of (3HgSe) 0.5 (In 2 Se 3 ) 0.5 crystals doped with Mn or Fe

Abstract. The mean refractive index and the reflection coefficient of (3HgSe) 0.5 (In 2 Se 3 ) 0.5 crystals doped with Mn and Fe have been investigated basing on the studies of their optical reflectance and transmittance at the room temperature and the wavelengths of 0.9-26.6 μm. The influence of temperature on the optical transmittance has been studied in the interval of 125-300 K

Optical properties of thin Cu2ZnSnS4, 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

Optical properties of spin-coated SnS2 thin films

This paper reports optical properties of n-type SnS2 thin films, prepared by spin-coating of a sol-gel based on the lowcost and environmentally friendly solvent dimethyl sulfoxide (DMSO). The effect of a short-term low-temperature treatment in air and final annealing under low vacuum (0.1 Pa) on the synthesis of tin disulfide films was tested and analyzed. The dynamics of changes of optical properties of the films on the parameters of spin-coating and heat treatment was established. The value of the band gap Eg 2.25 - 2.54 eV for SnS2 and Eg 1.99 eV for Sn2S3 was determined from the analysis of optical characteristics

Study on Cu2ZnSnSe4 crystals and heterojunctions on their basis

The most promising materials for the solar radiation converters are such compounds as CdTe and Cu(In, Ga)Se2, CuIn(S, Se)2, CuGa(S, Se)2 solid solutions. However, the uneconomic nature of Cd, Te and the limited supply of In and Ga, as well as their high cost, force researchers to replace In and Ga with the more common elements of II and IV groups, namely Zn and Sn. Apart from that, researchers are now testing such new semiconductor compounds as ZnSnS4, Cu2ZnSnSe4, and solid solutions on their basis. These compounds have a band gap width (Eg ≈ 1.5 eV) close to optimal for the conversion of solar energy, a high light absorption coefficient (≈ 105cm-1), a long lifetime and a high mobility of charge carriers. Moreover, the interest in such semiconductor heterojunctions as TiO2/ZnSnS4, which have several advantages over homo-transitions, is steadily growing at present. The paper presents results studies of kinetic properties of Cu2ZnSnSe4 crystals. We fabricated n-TiO2/p-Cu2ZnSnSe4 anisotype heterojunctions, determined their main electrical parameters and built their energy diagram. The Cu2ZnSnSe4 crystals have p-type conductivity and the Hall coefficient practically independent of temperature. The temperature dependence of the electrical conductivity σ for Cu2ZnSnSe4 crystalsis metallic in character, i. e. σ decreases with increasing temperature, which is caused by a decrease in the mobility of the charge carriers with the growth of T. Thermoelectric power for the samples is positive, which also indicates the prevalence of p-type conductivity. In this study, the n-TiO2/p-Cu2ZnSnSe4 heterojunctions were produced by reactive magnetron sputtering of a thin TiO2 film on the Cu2ZnSnSe4 substrate. The energy diagram of the investigated n-TiO2/p-Cu2ZnSnSe4 anisotype heterojunctions was constructed in accordance with the Anderson model, without taking into account the surface electrical states and the dielectric layer, based on the values of the energy parameters of semiconductors determined experimentally and taken from literary sources. The authors have also investigated electrical properties of the heterojunctions: the value of the potential barrier was determined, the value of the series resistance and shunt resistance (respectively, Rs = 8 W and Rsh = 5.8 kW) at room temperature. The dominant mechanisms of current transfer were established: tunneling-recombination mechanism in the voltage range from 0 to 0.3 V, and over-barrier emission and tunneling with inverse displacement in the voltage range from 0.3 to 0.45 V