Electronic properties of MoS2/MoOx interfaces: Implications in Tunnel Field Effect Transistors and Hole Contacts

Santosh K C; Roberto C Longo; Rafik Addou; Robert M Wallace; Kyeongjae Cho

doi:10.1038/srep33562

Electronic properties of MoS₂/MoO_x interfaces: Implications in Tunnel Field Effect Transistors and Hole Contacts

Sci Rep. 2016 Sep 26:6:33562. doi: 10.1038/srep33562.

Authors

Santosh K C^{1

2}, Roberto C Longo¹, Rafik Addou¹, Robert M Wallace^{1

3}, Kyeongjae Cho^{1

3}

Affiliations

¹ Department of Materials Science &Engineering, The University of Texas at Dallas, Richardson, TX 75080 USA.
² Materials Science and Technology Division, Oak Ridge National Laboratory, Bethel Valley Road, Oak Ridge, Tennessee 37831, USA.
³ Department of Physics, The University of Texas at Dallas, Richardson, TX 75080 USA.

Abstract

In an electronic device based on two dimensional (2D) transitional metal dichalcogenides (TMDs), finding a low resistance metal contact is critical in order to achieve the desired performance. However, due to the unusual Fermi level pinning in metal/2D TMD interface, the performance is limited. Here, we investigate the electronic properties of TMDs and transition metal oxide (TMO) interfaces (MoS₂/MoO₃) using density functional theory (DFT). Our results demonstrate that, due to the large work function of MoO₃ and the relative band alignment with MoS₂, together with small energy gap, the MoS₂/MoO₃ interface is a good candidate for a tunnel field effect (TFET)-type device. Moreover, if the interface is not stoichiometric because of the presence of oxygen vacancies in MoO₃, the heterostructure is more suitable for p-type (hole) contacts, exhibiting an Ohmic electrical behavior as experimentally demonstrated for different TMO/TMD interfaces. Our results reveal that the defect state induced by an oxygen vacancy in the MoO₃ aligns with the valance band of MoS₂, showing an insignificant impact on the band gap of the TMD. This result highlights the role of oxygen vacancies in oxides on facilitating appropriate contacts at the MoS₂ and MoO_x (x < 3) interface, which consistently explains the available experimental observations.