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In the search for two-dimensional (2D) materials, transition-metal trichalcogenides (TMTCs) have emerged as promising candidates for optoelectronic applications. Here, we show a very long-lasting persistent photoconductivity (PPC) over several hours in thin films of the TMTC zirconium trisulfide (ZrS3) at room temperature when illuminated with a 470 nm LED. ZrS3 crystals were grown using chemical vapor transport. UV-vis spectroscopy showed an indirect band gap of 1.81 eV and an Urbach energy of 83 meV, indicating that the system has a large number of defects. Transistor measurements on thin layers with thicknesses varying between 19 and 50 nm showed ZrS3 to be an n-type semiconductor. The conductivity increases under illumination, and it only reaches the original state several hours after switching off the illumination. This PPC can be described by using a stretched exponential function. On top of that, the sum of three exponential functions with tree different relaxation times fits the observed PPC nearly equally well. This shows that three processes dominate the relaxation. The three observed processes can be differentiated with respect to their origin by their dependence on the thickness of the thin layers.

In the search for two-dimensional (2D) materials, transition-metal trichalcogenides (TMTCs) have emerged as promising candidates for optoelectronic applications. Here, we show a very long-lasting persistent photoconductivity (PPC) over several hours in thin films of the TMTC zirconium trisulfide (ZrS3) at room temperature when illuminated with a 470 nm LED. ZrS3 crystals were grown using chemical vapor transport. UV-vis spectroscopy showed an indirect band gap of 1.81 eV and an Urbach energy of 83 meV, indicating that the system has a large number of defects. Transistor measurements on thin layers with thicknesses varying between 19 and 50 nm showed ZrS3 to be an n-type semiconductor. The conductivity increases under illumination, and it only reaches the original state several hours after switching off the illumination. This PPC can be described by using a stretched exponential function. On top of that, the sum of three exponential functions with tree different relaxation times fits the observed PPC nearly equally well. This shows that three processes dominate the relaxation. The three observed processes can be differentiated with respect to their origin by their dependence on the thickness of the thin layers.

We present the analysis of a family of nanotubes (NTs) based on the quaternary misfit layered compound (MLC) YxLa1-xS-TaS2. The NTs were successfully synthesized within the whole range of possible compositions via the chemical vapor transport technique. In-depth analysis of the NTs using electron microscopy and spectroscopy proves the in-phase (partial) substitution of La by Y in the (La,Y)S subsystem and reveals structural changes compared to the previously reported LaS-TaS2 MLC-NTs. The observed structure can be linked to the slightly different lattice parameters of LaS and YS. Raman spectroscopy and infrared transmission measurements reveal the tunability of the plasmonic and vibrational properties. Density-functional theory calculations showed that the YxLa1-xS-TaS2 MLCs are stable in all compositions. Moreover, the calculations indicated that substitution of La by Sc atoms is electronically not favorable, which explains our failed attempt to synthesize these MLC and NTs thereof. © 2020 American Chemical Society.

A comparative analysis of free and bound excitons in the photoluminescence (PL) spectra of CuInS2 single crystals grown by the traveling heater (THM) and the chemical vapor transport (CVT) methods is presented. The values of the binding energy of the A free exciton (18.5 and 19.7 meV), determined by measurements of the spectral positions of the ground and excited states, allowed the Bohr radii (3.8 and 3.7 nm), bandgaps (1.5536 and 1.5548 eV) and dielectric constants (10.2 and 9.9) to be calculated for CuInS2 crystals grown by THM and CVT, respectively. © 2017 Elsevier B.V.

Highly symmetric arranged ZnO nanowire arrays are produced by laser interference lithography and chemical vapor transport process. The resulting ZnO nanowires show a narrow diameter distribution as well as a uniform spacing. Liquid-phase assistant vapor-solid mechanism is proposed for one-to-one synthesized ZnO nanowires growth. Scanning cathodoluminescence microscopy is used to characterize the optical properties.

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