Search NASA⌕ Search

Engineering topics

Finkelstein, G.

Publications and source records attributed to Finkelstein, G..

One-dimensional edge contact to encapsulated MoS 2 with a superconductor

Establishing ohmic contact to van der Waals semiconductors such as MoS 2 is crucial to unlocking their full potential in next-generation electronic devices. Encapsulation of few layer MoS 2 with hBN preserves the material’s electronic properties but makes electrical contacts more challenging. Progress toward high quality edge contact to encapsulated MoS 2 has been recently reported. Here, we evaluate a contact methodology using sputtered MoRe, a type II superconductor with a relatively high critical field and temperature commonly used to induce superconductivity in graphene. We find that the contact transparency is poor and that the devices do not support a measurable supercurrent down to 3 K, which has ramifications for future fabrication recipes.

2D materials↗

Chiral quasiparticle tunneling between quantum Hall edges in proximity with a superconductor

We study a two-terminal graphene Josephson junction with contacts shaped to form a narrow constriction, less than 100 nm in length. The contacts are made from type-II superconducting contacts and able to withstand magnetic fields high enough to reach the quantum Hall regime in graphene. In this regime, the device conductance is determined by edge states, plus the contribution from the constricted region. In particular, the constriction area can support supercurrents up to fields of ~2.5 T. Additionally, enhanced conductance is observed through a wide range of magnetic fields and gate voltages. In conclusion, this additional conductance and the appearance of supercurrent is attributed to the tunneling between counterpropagating quantum Hall edge states along opposite superconducting contacts.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗

Subkelvin lateral thermal transport in diffusive graphene

In this work, we report on hot carrier diffusion in graphene across large enough length scales that the carriers are not thermalized across the crystal. The carriers are injected into graphene at one site and their thermal transport is studied as a function of applied power and distance from the heating source, up to tens of micrometers away. Superconducting contacts prevent out-diffusion of hot carriers to isolate the electron-phonon coupling as the sole channel for thermal relaxation. As local thermometers, we use the amplitude of the universal conductance fluctuations, which varies monotonically as a function of temperature. By measuring the electron temperature simultaneously along the length we observe a thermal gradient which results from the competition between electron-phonon cooling and lateral heat flow.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗