Abstract-Superconducting Contacts for Terahertz Photon Detection

• Christopher B. McKitterick, 
• Heli Vora, 
• Xu Du, 
• Boris S. Karasik, 
• Daniel E. Prober

http://link.springer.com/article/10.1007%2Fs10909-014-1127-3

We report on noise and thermal conductance measurements taken in order to determine an upper bound on the performance of graphene as a terahertz photon detector. The main mechanism for sensitive terahertz detection in graphene is bolometric heating of the electron system. To study the properties of a device using this mechanism to detect terahertz photons, we perform Johnson noise thermometry measurements on graphene samples. These measurements probe the electron–phonon behavior of graphene on silicon dioxide at low temperatures. Because the electron–phonon coupling is weak in graphene, superconducting contacts with large gap are used to confine the hot electrons and prevent their out-diffusion. We use niobium nitride leads with a

Tc≈10 K to contact the graphene. We find these leads make good ohmic contact with very low contact resistance. Our measurements find an electron–phonon thermal conductance that depends quadratically on temperature above 4 K and is compatible with single terahertz photon detection.

Abstract-Terahertz Detectors based on graphene

Fathi Gouider¹, Majdi Salman^1,2, Markus Göthlich¹, Hennrik Schmidt^2,3, Franz-J Ahlers⁴, Rolf Haug³ and Georg Nachtwei¹

f.gouider@tu-bs.de                            
¹ Institut für Angewandte Physik, Technische Universität Braunschweig, D-38106, Germany
² NTH Nano School for Contacts in Nanosystems, Germany
³ Institut für Festkörperphysik, Universität Hannover, Hannover, D-30167, Germany
⁴ Physikalisch-Technische Bundesanstalt, Braunschweig, D-38116, German
y

In this study we present magnetotransport an magnetooptical data obtained in the magnetic field range 0T < B < 7T at detectors patterned in Corbino geometry on epitaxial graphene wafer using a Ge detector. We observed the cyclotron resonance of charge carriers in these wafers by measurement of the transmission of THz wafes through the unpatterned squares (about 4 × 4mm²) of the wafers as a function of the magnetic field B applied perpendicular to the wafer. Further, we performed measurements of the photocunductivity of graphene-based devices shaped in Corbino geometry, induced by terahertz (THz) radiation generated by a p-Ge laser (emitting in the energy range 7.5meV ≤ E_ph ≤ 11meV). Our photoconductivity measurement imply that graphene devices are suitable for the detection of terahertz radiation.

Abstract-Graphene microbolometers with superconducting contacts for terahertz photon detection

Christopher B. McKitterick, Heli Vora, Xu Du, Boris S. Karasik and Daniel E. Prober
Christopher B. McKitterick
Daniel E. Prober at Departments of Physics and Applied Physics, Yale University, New Haven, Connecticut 06520, USA (email: chris.mckitterick@yale.edu) (email: daniel.prober@yale.edu)
Heli Vora
Xu Du at Department of Physics, Stony Brook University, Stony Brook, New York 11790, USA
Boris S. Karasik at Jet Propulsion Laboratory, California Institute of Technology, Pasadena, California
http://eprintweb.org/S/article/cond-mat/1307.5012

Abstract. We report on noise and thermal conductance measurements taken in order to determine an upper bound on the performance of graphene as a terahertz photon detector. The main mechanism for sensitive terahertz detection in graphene is bolometric heating of the electron system. To study the properties of a device using this mechanism to detect terahertz photons, we perform Johnson noise thermometry measurements on graphene samples. These measurements probe the electron-phonon behavior of graphene on silicon dioxide at low temperatures. Because the electron-phonon coupling is weak in graphene, superconducting contacts with large gap are used to confine the hot electrons and prevent their out-diffusion. We use niobium nitride leads with a $T_mathrmcapprox 10$ K to contact the graphene. We find these leads make good ohmic contact with very low contact resistance. Our measurements find an electron-phonon thermal conductance that depends quadratically on temperature above 4 K and is compatible with single terahertz photon detection.