Highly Sensitive Detector for On-Chip Near-Field THz Imaging

We present novel terahertz (THz) detectors, using nanoelectronic devices, such as 2-D semiconductor and carbon nanotube (CNT). Our detector is useful for high-resolution THz imaging, which requires highly sensitive detection. We have developed a frequency-tunable THz-photon detector and an on-chip near-field imaging detector. The detection mechanism of the former is that the CNT transistor detects electrical polarization generated by THz-excited electron-hole pairs in the 2-D semiconductor. In the latter, we have achieved THz imaging beyond the diffraction limit with an all-integrated device, including an aperture, a probe, and a detector. We further show applications of the THz imaging to semiconductor research. We have successfully visualized and clarified spatial properties of electrons in the 2-D semiconductors, which have not been revealed by conventional transport measurements.