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 (σ/τ) in the order of 1020. 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 ≈60 mV dec−1 and field–effect mobilities of ≈160 cm−2 V−1 s−1. MoS2/MoSe2 type‐I heterojunction presents a correlation between layers alignment and band gap. At some situations of alignment, a semi‐metal character arises due to overlapping of orbitals. The results show that this new material has potential applications in field–effect transistors and solar cells, due to the beneficial and specific band alignment.