Synthesis and wavelength-sensitive near-infrared photodetection performance of large-diameter single-walled carbon nanotubes with tailored bandgap distribution

• Applicant: Professor Dr. Ralph Krupke
• Subject Area: Electronic Semiconductors, Components and Circuits, Integrated Systems, Sensor Technology, Theoretical Electrical Engineering ; Synthesis and Properties of Functional Materials
• Term: from 2018 to 2022
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 392403255

Single-walled carbon nanotubes (SWCNTs) exist in different electronic types with tunable band gaps depending on their structure. Semiconducting (s-) SWCNTs are also able to selectively absorb light in the near-infrared (NIR) range from below one micron all the way through the technologically important telecom band up to several microns. In consequence, SWCNTs have been regarded as an ideal material for wavelength-sensitive NIR photodetection, which are expected to be used in new-generation photoconductors, optical diodes, and optical transistors. However, the performance of SWCNT-based detectors has been limited mainly due to the fact that as-grown SWCNTs usually contain both metallic and s- nanotubes, and the former is highly undesirable for efficient photodetection. Therefore, we propose to fabricate wavelength-sensitive NIR photodetectors using large-diameter s-SWCNTs with tailored band gap distributions and to study the performance and working mechanism of the devices obtained. This work will be a joint research effort of the IMR team and the Darmstadt/Karlsruhe team, bringing in their unique expertise in the controlled synthesis of SWCNTs and the integration of SWCNTs into device architectures. We will establish a floating catalyst chemical vapor deposition approach for the continuous, controllable synthesis of high-quality s-SWCNTs with tailored band gaps by combining catalyst design and in-situ etching. The band gap distribution will be further optimized by hetero-atom doping or liquid phase chromatography. We will fabricate photodetectors using large-diameter s-SWCNTs with tailored band gap distributions either on the basis of s-SWCNT films or from solution via dielectrophoresis, measure the spatially and spectrally resolved photocurrent response, and thereby reveal the mechanism of photocurrent generation. We develop a device architecture that allows efficient conversion of light into current for the targeted wavelength range will be developed and optimized SWCNT-based NIR photodetectors with good reproducibility and long term stability are targeted. Besides addressing fundamental questions related to the controlled synthesis of large-diameter, semiconducting SWCNTs and the photocurrent generation in the NIR from SWCNTs with small bandgap, the development of NIR photodetectors with wavelength-specific absorption will constitute an important step towards NIR spectrometry without dispersing elements.

• DFG Programme: Research Grants
• International Connection: China
• Cooperation Partner: Professor Dr. Chang Liu