Van der Waals Contact to 2D Semiconductors with a Switchable Electric Dipole: Achieving Both n‐ and p‐Type Ohmic Contacts to Metals with a Wide Range of Work Functions

Abstract

Two‐dimensional (2D) layered semiconductors with an intrinsic electric dipole p (pS for short), including group III2‐VI3 ferroelectrics and various Janus semiconductors, are attracting increasing attention for their exotic properties and versatile applications. Their potential in metal–semiconductor junctions is revealed. It is demonstrated that, for pS contacting to 2D metals with a wide range of work‐functions, Schottky‐barrier‐free (SB‐free) and tunable n‐ to p‐type contacts can be obtained, which is important for complementary metal‐oxide‐semiconductor logical circuitry. As expected, low (high) work‐function (WF) metals form n‐type (p‐type) SB‐free contacts to pS. What is unexpected is the behavior of medium‐WF metal‐pS junctions (MpSJ); that is, by switching the polarization in pS, both n‐ and p‐type SB‐free contacts can be obtained by the same pS contacting to metals with a wide range of WF. More importantly, MpSJ with bilayer pS can form both n‐ and p‐type SB‐free contacts. These findings, SB‐free and contact‐type‐tunable of MpSJ for metals with a wide range of work‐functions, demonstrate the great potential of 2D pS for device applications.

Tunable Properties of Novel Ga2O3 Monolayer for Electronic and Optoelectronic Applications

“…When studying the electronic properties of the Ga 2 O 3 monolayer, the asymmetric atomic configuration should be taken into consideration. Analogous to other polar 2D materials such as Janus TMDs, , there exists an intrinsic electric field in 2D M 2 X 3 materials due to the breaking of centrosymmetry; , thus, intrinsic dipole , forms even within the pristine materials. The electrostatic potential curve of the Ga 2 O 3 monolayer along the z direction is plotted in Figure b.…”

Janus Ga2SeTe/In2SSe heterostructures: tunable electronic, optical, and photocatalytic properties

“…The out of plane structural symmetry is broken in the Janus Ga 2 SeTe (In 2 SSe) and an internal electric dipole is developed, because the Se and Te (S and Se) elements have different electronegativity. 57 Thus the two vacuum levels for the Janus Ga 2 SeTe (In 2 SSe) monolayer ( 001) and (00À1) surfaces are very different, see Fig. 1(e) and (f).…”

Tunable Schottky and ohmic contacts in the Ti2NF2/α-Te van der Waals heterostructure

“…1c). 53,54,66,67 Hence, the Schottky-Mott rule should be modified and the observed SB height follows F Bn = W MXene -w a-Te -DV and F Bp = I a -Te-W MXene + DV, where W M is the work function of Ti 2 NF 2 and I a -Te and w a-Te are the electron affinity and ionization potential of a-Te, respectively. The calculated I a -Te and w a-Te values are 5.32 and 4.57 eV, respectively, which are in good agreement with the previous work.…”