The unique optoelectronic properties of graphene make it an ideal platform for a variety of photonic applications, including fast photodetectors, transparent electrodes in displays and photovoltaic modules, optical modulators, plasmonic devices, microcavities, and ultra-fast lasers. Owing to its high carrier mobility, gapless spectrum and frequency-independent absorption, graphene is a very promising material for the development of detectors and modulators operating in the terahertz region of the electromagnetic spectrum (wavelengths in the hundreds of micrometres), still severely lacking in terms of solid-state devices. Here we demonstrate terahertz detectors based on antenna-coupled graphene field-effect transistors. These exploit the nonlinear response to the oscillating radiation field at the gate electrode, with contributions of thermoelectric and photoconductive origin. We demonstrate room temperature operation at 0.3 THz, showing that our devices can already be used in realistic settings, enabling large-area, fast imaging of macroscopic samples.

http://arxiv.org/abs/1310.0969 The authors acknowledge helpful discussions with T. Brauner, R. Grill, M. Grynberg, A. A. Nersesyan, V. Novák, M. L. Sadowski and W. Zawadzki. The work has been supported by the ERC project MOMB, by EuroMagNET II under the EU Contract No. 228043, by the GDR-I project 'Semiconductor sources and detectors of THz frequencies' and by the Scientific Council of Montpellier II University. We also acknowledge the support received from the Ambassade de France en Russie for the French-Russian collaboration and exchange of PhD students.International audienceSolid-state physics and quantum electrodynamics, with its ultrarelativistic (massless) particles, meet in the electronic properties of one-dimensional carbon nanotubes, two-dimensional graphene or topological-insulator surfaces. However, clear experimental evidence for electronic states with a conical dispersion relation in all three dimensions, conceivable for certain bulk materials, is still missing. Here, we study a zinc-blende crystal, HgCdTe, at the point of the semiconductor-to-semimetal topological transition. For this compound, we observe three-dimensional massless electrons, as certified from the dynamical conductivity increasing linearly with the photon frequency, with a velocity of about 106 m s−1. Applying a magnetic field B results in a -dependence of dipole-active inter-Landau-level resonances and spin splitting of Landau levels also following a -dependence--well-established signatures of ultrarelativistic particles but until now not observed experimentally in any solid-state electronic system

The first room-temperature terahertz (THz)-frequency nanodetector exploiting a 10 nm thick flake of exfoliated crystalline black phosphorus as an active channel of a field-effect transistor, is devised. By engineering and embedding planar THz antennas for efficient light harvesting, the first technological demonstration of a phosphorus-based active THz device is described.