研究目的
To study the possibility of photoactivation-based engineering of the direct-current (dc) conductance in the case of partially ordered assemblies of densely packed anatase TNTAs and to better understand the physical mechanisms of charge carrier transfer in the anatase-based nanostructured materials.
研究成果
The study highlights the features of long-range transport of charge carriers throughout the aTNTAs, including strong coupling of charge carriers with phonons and the hopping character of inter-tubular charge transfer. The results suggest that the macroscopic dc conductivity is governed by the diffusion transfer of carriers due to the suppression of the drift current by the internal confining field. These findings are important for the development of electronic units based on aTNTAs.
研究不足
The study acknowledges the extremely low values of charge mobility in the examined aTNTAs due to strong charge-phonon coupling and abundance of shallow traps. The long-range charge transport is limited by high barriers at the interfaces between adjacent nanotubes, leading to low-efficiency macroscopic transport of mobile carriers.
1：Experimental Design and Method Selection:
The study involved the synthesis of anatase TiO2 nanotubular arrays (aTNTAs) by electrochemical anodization of titanium foil, followed by characterization using scanning electron microscopy (SEM). The photoactivated dc conductance of aTNTAs was measured under pulsed laser irradiation inside and outside the fundamental absorption band.
2：Sample Selection and Data Sources:
The aTNTA layer was fabricated by electrochemical anodization of titanium foil and characterized by SEM. The electrical contact at the layer/electrode interface was checked by I-V measurements.
3：List of Experimental Equipment and Materials:
A wavelength-tunable parametric computer-aided laser system (LS 2145 OPO type, Lotis TII) was used as a source of probe light. The setup included a high-gain current amplifier (SRS-570) and a multimeter (Keithley 2000) for measuring the dc conductance.
4：Experimental Procedures and Operational Workflow:
The aTNTA layer was irradiated by a diverging laser beam formed using a convex lens. The dc conductance was measured under various irradiation conditions, including different pulse energies, repetition rates, and wavelengths.
5：Data Analysis Methods:
The decay kinetics of the photo-induced dc conductance were analyzed using a kinetic equation, and the quantum yield of photo-activation was estimated based on the number of absorbed photons and the excess photo-generated charge.
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