Search

Photodissociation kinetics of iron–boron (FeB) pairs in boron‐doped Czochralski silicon is studied experimentally using different light sources. It is shown that the FeB dissociation rate depends not only on integrated light intensity and overall carrier generation rate, but also on spectral composition of illumination. The value of the material constant of dissociation K varies and has been determined to be within (1.5−3.8)×10−15$\left(\right. 1.5 - 3.8 \left.\right) \times \left(10\right)^{- 15}$ s. The investigation reveals an increase in the dissociation rate with increase in photon energy. The results indicate that recombination‐enhanced defect reaction is the primary factor in the second stage of pair dissociation. [ABSTRACT FROM AUTHOR]

This study describes the fabrication of hybrid two-dimensional (2D)-quantum dot (QD) MoS2–AgInS2 photoconductive devices through the mechanical pressing of a MoS2 flake onto an AgInS2 QD film. The devices exhibit an enhanced photoresponse at both continuous and modulated optical excitations, compared with the bare MoS2 or AgInS2 layer, due to the formation of a built-in electric field near the MoS2/AgInS2 interface. The continuous wave photoresponse is significantly higher due to the effective photoconductive gain when electrons flow freely through the MoS2 flake, whereas holes are effectively trapped in AgInS2 QDs. The study highlights the potential of hybrid 2D-QD MoS2–AgInS2 devices for photovoltaic and optoelectronic applications. [ABSTRACT FROM AUTHOR]

A portable voltammetric sensor for toxicity assessment was developed based on a screen‐printed carbon electrode modified with SiO2‐CuO‐glucose oxidase (GOx) film. The method is based on the detection of the metabolic activity of E. coli towards glucose as an indicator systems in the presence of antiseptic drugs as model toxic compounds. CuO particles exhibited catalytic activity toward hydrogen peroxide produced by the GOx‐induced oxidation of glucose. A well‐defined reduction peak was registered at E=−0.50 V (vs. Ag/AgCl). The metabolism of glucose by E. coli resulted in a decrease in analytical signal of glucose with the increasing bacteria content in the range of 0.8×109–5.0×109 CFU mL−1 with a calculated limit of detection (LOD) of 0.59×109 CFU mL−1. To evaluate the effect of antiseptics the biosensor was tested in E. coli solution with chlorhexidine (CHD) or decamethoxine (DMT). A linear dependence of glucose consumption by E. coli solution on the antiseptic concentration was obtained in the range of 3.0–12.0 μg mL−1 for CHG and 1.0–12.0 μg mL−1 for DMT, respectively. The developed third generation biosensor showed satisfactory stability and reproducibility of the analytical response. A modified electrode can be used for at least two months. [ABSTRACT FROM AUTHOR]

Elastic strain engineering in the GeSn bandgap structure is an attractive area for designing novel material properties. The linear interpolation of the elastic constants of Ge and Sn is commonly used to estimate their respective values for Ge1−xSnx alloys. This work reveals that Young's modulus of Ge1−xSnx epitaxial layers has a non-monotonic dependence on Sn composition. It is shown that the decrease in the elastic modulus correlates with the increase in Sn content in pseudomorphically grown Ge1−xSnx-epilayers with Sn concentration in the range of 1–5 at. % and subcritical thicknesses. An anomalous increase in the elastic modulus is observed with the further increase in Sn content (12 at. %), which is also accompanied by an increase in in-plane tensile strain. Phase separation and a decrease in the elastic modulus are observed for Ge1−xSnx-epilayers grown above the critical thickness with Sn concentration ≥ 12 at. %. A correlation between the experimental elastic moduli and calculated elastic energies explains the complexity of strain-driven anomalous elastic properties of Ge1−xSnx-epilayers. The observed anomalous behavior of the Young's modulus for these GeSn epitaxial layers appears to be related to their recently predicted and observed short-range atomic order. [ABSTRACT FROM AUTHOR]

Element substitution in Cu2ZnSnS4‐like chalcogenides offers the potential to create alternative low‐cost photovoltaic and thermoelectric materials with tunable properties. In this work, the “green” synthesis of colloidal cation‐substituted Cu–Ni–Sn–S nanocrystals (CNTS NCs) in aqueous solutions using thioglycolic acid as a stabilizer is reported for the first time. The structural and optical properties of CNTS NCs are studied in colloidal solutions and thin films, and are compared with those of Cu–Zn–Sn–S (CZTS) NCs obtained under similar conditions. The NC sizes of both compounds are estimated to be in the range of 1.5–2.5 nm. Both NCs exhibit strongly non‐stoichiometric composition and a structure corresponding to cationically disordered kesterite Cu2ZnSnS4, which are common features of such quaternary metal‐based chalcogenides. The phonon Raman spectra of CNTS and CZTS NCs exhibit very similar lineshapes, but the CNTS phonon band has a larger width and lower frequency, presumably due to stronger cation disorder. The absorption of both types of NCs extends continuously through the visible range with an estimated bandgap of ≈2.2 eV and sub‐bandgap absorption due to an Urbach tail. The absorption coefficient of CNTS is determined to be α > 102 cm−1 at 700 nm and α > 104 cm−1 at 400 nm. [ABSTRACT FROM AUTHOR]