Transient Photoconductivity of Ternary CdSSe Nanobelts As Measured by Time-Resolved Terahertz Spectroscopy

• Published in: Journal of physical chemistry. C 2013-06, Vol.117 (23), p.12379-12384
• Main Authors: Lu, Junpeng, Liu, Hongwei, Lim, Sharon Xiaodai, Tang, Sing Hai, Sow, Chorng Haur, Zhang, Xinhai
• Format: Article
• Language: English
• Subjects: Condensed matter: electronic structure, electrical, magnetic, and optical properties; Cross-disciplinary physics: materials science; rheology; Electronic structure and electrical properties of surfaces, interfaces, thin films and low-dimensional structures; Electronic transport in multilayers, nanoscale materials and structures; Electronic transport phenomena in thin films and low-dimensional structures; Exact sciences and technology; Materials science; Nanoscale materials and structures: fabrication and characterization; Other topics in nanoscale materials and structures; Photoconduction and photovoltaic effects; photodielectric effects; Physics; Quantum wires
• ISSN: 1932-7447; 1932-7455
• DOI: 10.1021/jp4043599

The frequency- and fluence-dependent transient photoconductivity in ternary CdSSe nanobelts is investigated using time-resolved terahertz spectroscopy. The carrier density and mobility are extracted by modeling the measured complex photoconductivity using the Drude–Smith model. Within the first few picoseconds of excitation, both the carrier density and mobility reach their maximum values and then decay gradually over tens to hundreds of picoseconds. The decay of free carriers is mainly attributed to fast surface trapping and structural-defect-mediated recombination. The surface trapping saturates rapidly with increasing excitation fluence attributable to the low trapping density on the nanobelt surface caused by self-passivation of surface defects during the growth process.