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 generation with ballistic photodiodes under pulsed operation

Stefan Malzer, Christian Müller-Landau, Heiko B Weber, Gottfried H Döhler, Stephan Winner,  Peter G Burke, Arthur Gossard,  Sascha Preu

http://iopscience.iop.org/article/10.1088/1361-6641/aae5e4

We investigate high field and ballistic carrier transport in a 1.55 μm photomixing
 device based on pin-diodes by time resolved terahertz (THz) spectroscopy. The device
 consists of 3 stacked In(Al)GaAs pin diodes (n-i-pn-i-p superlattice) attached to a
 broadband logarithmic-periodic antenna. Each pin diode is optimized for exhibiting
 ballistic transport and a reduced transit time roll-off. Ballistic transport signatures
 could be confirmed directly in these experiments. The data are compared with results
 from continuous-wave (CW) experiments and from simulations both supporting our
 theoretical expectations. It is demonstrated that n-i-pn-i-p superlattice photomixers
 are also efficient THz emitters under pulsed operation, showing a maximum THz field
 strength of ~0.5 V/cm (peak to peak) at 30 mW average optical power.