Double-well potential energy surface in the interaction between h-BN and Ni(111)

Reduced Fermi Level Pinning at Physisorptive Sites of Moire-MoS2/Metal Schottky Barriers

Weaker Fermi level pinning (FLP) at the Schottky barriers of 2D semiconductors is electrically desirable as this would allow a minimizing of contact resistances, which presently limit device performances. Existing contacts on MoS₂ have a strong FLP with a small pinning factor of only ∼0.1. Here, we show that Moire interfaces can stabilize physisorptive sites at the Schottky barriers with a much weaker interaction without significantly lengthening the bonds. This increases the pinning factor up to ∼0.37 and greatly reduces the n-type Schottky barrier height to ∼0.2 eV for certain metals such as In and Ag, which can have physisorptive sites. This then accounts for the low contact resistance of these metals as seen experimentally. Such physisorptive interfaces can be extended to similar systems to better control SBHs in highly scaled 2D devices.

Ab Initio Study of Hexagonal Boron Nitride as the Tunnel Barrier in Magnetic Tunnel Junctions

Two-dimensional hexagonal boron nitride (h-BN) is studied as a tunnel barrier in magnetic tunnel junctions (MTJs) as a possible alternative to MgO. The tunnel magnetoresistance (TMR) of such MTJs is calculated as a function of whether the interface involves the chemi- or physisorptive site of h-BN atoms on the metal electrodes, Fe, Co, or Ni. It is found that the physisorptive site on average produces higher TMR values, whereas the chemisorptive site has the greater binding energy but lower TMR. It is found that alloying the electrodes with an inert metal-like Pt can induce the preferred absorption site on Co to become a physisorptive site, enabling a higher TMR value. It is found that the choice of physisorptive sites of each element gives more Schottky-like dependence of their Schottky barrier heights on the metal work function.