Robust Low-Bias Negative Differential Resistance in Graphene   Superlattices
  Here, we present a detailed study on low bias current-voltage (I-V) characteristic of graphene superlattice (GSL) resonant tunneling diode (RTD) with heterostructured substrate and series of grounded metallic planes placed over graphene sheet which induce periodically modulated Dirac gap and Fermi velocity barrier. We investigate the effect of GSL parameters on I-V characteristics within the Landauer-Buttiker formalism and adopted transfer matrix method. We show how the engineering these parameters results in multipeak NDR in proposed device. Moreover we provide a novel venue to control the NDR in GSL with Fermi velocity engineering. From this viewpoint we obtain multipeak NDR through miniband align in GSL. Maximum Pick to Valley ratio (PVR) up to 167 obtained for correlation velocity of 1.9 and bias voltages between 70-130 mV. Our finding in low bias regime and high PVR multipeak NDR have a considerable importance in multi-valued memory functional circuit, low power and high-speed nanoelectronic devices application. 
S. M. Sattari Esfahlan, J. Fouladi Oskuei and S. Shojaei
cond-mat.mes-hall