Determining the Electronic Structure and Thermoelectric Properties of MoS2/MoSe2 Type-I Heterojunction by DFT and the Landauer Approach

The electronic structure and thermoelectric properties of MoX2 (X = S, Se) Van der Waals heterojunctions are reported, with the intention of motivating the design of electronic devices using such materials. Calculations indicate the proposed heterojunctions are thermodynamically stable and present a band gap reduction from 1.8 eV to 0.8 eV. The latter effect is highly related to interactions between metallic d-character orbitals and chalcogen p-character orbitals. The theoretical approach allows to predict a transition from semiconducting to semi-metallic behavior. The band alignment indicates a type-I heterojunction and band offsets of 0.2 eV. Transport properties show clear n-type nature and a high Seebeck coefficient at 300 K, along with conductivity values (sigma/tau) in the order of 10(20). Lastly, using the Landauer approach and ballistic transport, the proposed heterojunctions can be modeled as a channel material for a typical one-gate transistor configuration predicting subthreshold values of approximate to 60 mV dec(-1) and field-effect mobilities of approximate to 160 cm(-2) V-1 s(-1).

Automated summary

The electronic structure and thermoelectric properties of MoX2 (X = S, Se) Van der Waals heterojunctions are studied aiming to facilitate the design of electronic devices. The stable nature of the proposed heterojunctions and the reduction in band gap from 1.8 eV to 0.8 eV are revealed through calculations. The interaction between metallic d-character orbitals and chalcogen p-character orbitals plays a key role in this band gap reduction. Furthermore, it is predicted that the heterojunctions can exhibit a transition from semiconducting to semi-metallic behavior.