Abstract-An efficient Terahertz rectifier on the graphene/SiC materials platform

Maria T. Schlecht, Sascha Preu, Stefan Malzer,  Heiko B. Weber,

https://www.nature.com/articles/s41598-019-47606-6?utm_source=other_website&utm_medium=display&utm_content=leaderboard&utm_campaign=JRCN_2_LW_X-moldailyfeed

We present an efficient Schottky-diode detection scheme for Terahertz (THz) radiation, implemented on the material system epitaxial graphene on silicon carbide (SiC). It employs SiC as semiconductor and graphene as metal, with an epitaxially defined interface. For first prototypes, we report on broadband operation up to 580 GHz, limited only by the RC circuitry, with a responsivity of 1.1 A/W. Remarkably, the voltage dependence of the THz responsivity displays no deviations from DC responsivity, which encourages using this transparent device for exploring the high frequency limits of Schottky rectification in the optical regime. The performance of the detector is demonstrated by resolving sharp spectroscopic features of ethanol and acetone in a THz transmission experiment.

Abstract-Terahertz rectifier exploiting electric field-induced hot-carrier effect in asymmetric nano-electrode

Kiwon Moon, Jun-Hwan Shin, Il-Min Lee, Dong Woo Park, Eui Su Lee and Kyung Hyun Park,

http://iopscience.iop.org/article/10.1088/1361-6528/aae130/meta


Rectifiers have been used to detect electromagnetic waves with very low photon energies. In these rectifying devices, different methods have been utilized, such as adjusting the bandgap and the doping profile, or utilizing the contact potential of the metal–semiconductor junction to produce current flow depending on the direction of the electric field. In this paper, it is shown that the asymmetric application of nano-electrodes to a metal–semiconductor–metal (MSM) structure can produce such rectification characteristics, and a terahertz (THz) wave detector based on the nano-MSM structure is proposed. Integrated with a receiving antenna, the fabricated device detects THz radiation up to a frequency of 1.5 THz with responsivity and noise equivalent power of 10.8 V/W and  respectively, estimated at 0.3 THz. The unidirectional current flow is attributed to the thermionic emission of hot carriers accelerated by the locally enhanced THz field at the sharp end of the nano-electrode. This work not only demonstrates a new type of THz detector but also proposes a method for manipulating ultrafast charge-carrier dynamics through the field enhancement of the nano-electrode, which can be applied to ultrafast photonic and electronic devices.

Abstract-A Model of High-Frequency Self-Mixing in Double-Barrier Rectifier

Fabrizio Palma, R. Rao

https://link.springer.com/article/10.1007/s10762-018-0476-4

In this paper, a new model of the frequency dependence of the double-barrier THz rectifier is presented. The new structure is of interest because it can be realized by CMOS image sensor technology. Its application in a complex field such as that of THz receivers requires the availability of an analytical model, which is reliable and able to highlight the dependence on the parameters of the physical structure. The model is based on the hydrodynamic semiconductor equations, solved in the small signal approximation. The model depicts the mechanisms of the THz modulation of the charge in the depleted regions of the double-barrier device and explains the self-mixing process, the frequency dependence, and the detection capability of the structure. The model thus substantially improves the analytical models of the THz rectification available in literature, mainly based on lamped equivalent circuits.