Ramamoorthy, Harihara

Loading...
Thumbnail Image
Preferred name
Ramamoorthy, Harihara
Alternative Name
Ramamoorthy, H.
Main Affiliation
Email
harihara.ra@kmitl.ac.th

Settings

Now showing 1 - 4 of 4
  • Loading...
    Thumbnail Image
    Some of the metrics are blocked by your 
    consent settings
    Item type:Publication,
    Reversing hot-carrier energy-relaxation in graphene with a magnetic field
    (2014-05-12)
    Ramamoorthy, H.
    ;
    Somphonsane, R.
    ;
    He, G.
    ;
    Ferry, D. K.
    ;
    Ochiai, Y.
    We investigate the influence of a perpendicular magnetic field on hot-carrier energy relaxation in bilayer graphene. Working in the regime of incipient Landau quantization, we find that the magnetic field influences the relaxation in a very different manner, dependent upon the position of the Fermi level relative to the Dirac point. While for carrier densities >10 <sup>12</sup> cm<sup>-2</sup> relaxation is slowed by the magnetic field, as the density of free carriers approaches zero it instead becomes quicker. We discuss this behavior in terms of the emergence of the zero-energy Landau level, and the role of charge puddling in graphene. © 2014 AIP Publishing LLC.
  • Loading...
    Thumbnail Image
    Some of the metrics are blocked by your 
    consent settings
    Item type:Publication,
    Remote Mesoscopic Signatures of Induced Magnetic Texture in Graphene
    (2021-02-25)
    Arabchigavkani, N.
    ;
    Somphonsane, R.
    ;
    Ramamoorthy, H.
    ;
    He, G.
    ;
    Nathawat, J.
    Mesoscopic conductance fluctuations are a ubiquitous signature of phase-coherent transport in small conductors, exhibiting universal character independent of system details. In this Letter, however, we demonstrate a pronounced breakdown of this universality, due to the interplay of local and remote phenomena in transport. Our experiments are performed in a graphene-based interaction-detection geometry, in which an artificial magnetic texture is induced in the graphene layer by covering a portion of it with a micromagnet. When probing conduction at some distance from this region, the strong influence of remote factors is manifested through the appearance of giant conductance fluctuations, with amplitude much larger than e2/h. This violation of one of the fundamental tenets of mesoscopic physics dramatically demonstrates how local considerations can be overwhelmed by remote signatures in phase-coherent conductors.
  • Loading...
    Thumbnail Image
    Some of the metrics are blocked by your 
    consent settings
    Item type:Publication,
    Conduction Mechanisms in CVD-Grown Monolayer MoS2 Transistors: From Variable-Range Hopping to Velocity Saturation
    (2015-08-12)
    He, G.
    ;
    Ghosh, K.
    ;
    Singisetti, U.
    ;
    Ramamoorthy, H.
    ;
    Somphonsane, R.
    We fabricate transistors from chemical vapor deposition-grown monolayer MoS<inf>2</inf> crystals and demonstrate excellent current saturation at large drain voltages (V<inf>d</inf>). The low-field characteristics of these devices indicate that the electron mobility is likely limited by scattering from charged impurities. The current-voltage characteristics exhibit variable range hopping at low V<inf>d</inf> and evidence of velocity saturation at higher V<inf>d</inf>. This work confirms the excellent potential of MoS<inf>2</inf> as a possible channel-replacement material and highlights the role of multiple transport phenomena in governing its transistor action.
  • Loading...
    Thumbnail Image
    Some of the metrics are blocked by your 
    consent settings
    Item type:Publication,
    Thermally Assisted Nonvolatile Memory in Monolayer MoS2 Transistors
    (2016-10-12)
    He, G.
    ;
    Ramamoorthy, H.
    ;
    Kwan, C. P.
    ;
    Lee, Y. H.
    ;
    Nathawat, J.
    We demonstrate a novel form of thermally-assisted hysteresis in the transfer curves of monolayer MoS<inf>2</inf> FETs, characterized by the appearance of a large gate-voltage window and distinct current levels that differ by a factor of ∼10<sup>2</sup>. The hysteresis emerges for temperatures in excess of 400 K and, from studies in which the gate-voltage sweep parameters are varied, appears to be related to charge injection into the SiO<inf>2</inf> gate dielectric. The thermally-assisted memory is strongly suppressed in equivalent measurements performed on bilayer transistors, suggesting that weak screening in the monolayer system plays a vital role in generating its strongly sensitive response to the charge-injection process. By exploiting the full features of the hysteretic transfer curves, programmable memory operation is demonstrated. The essential principles demonstrated here point the way to a new class of thermally assisted memories based on atomically thin two-dimensional semiconductors.