Stabilizing Lithium Intercalation in MoS2 for 2H-to-1T Phase Transition and Low-Resistance Edge Contacts

Lithium intercalation in MoS 2 drives the transformation from its semiconducting 2H to metallic 1T/1T’ phase, allowing the fabrication of low-resistance edge contacts in transistors and diodes. However, due to the presence of chemically reactive lithium, the properties of the resulting Li x MoS 2 are sensitive to processing methods, raising additional concerns about its stability and performance when applied in electronic devices, which have rarely been discussed. Here, the processing method of lithium-intercalated MoS 2 in n-butyllithium solution is investigated for optimal edge contact performance in transistors. The stability of Li x MoS 2 when exposed to various solvents, ambient environment (air and vacuum) and thermal stress (from room temperature to 300 °C) is studied in terms of its electrical conductivity and phase ratio. It is found that exposure to water causes immediate degradation of the electrical conductivity of Li x MoS 2 , while under thermal stress, irreversible degradation occurs when the temperature exceeds 150 °C. Therefore, avoiding thermal stress during device fabrication is essential. Following this, an optimal procedure is proposed to fabricate low-resistance 1T-Li x MoS 2 edge contacts, achieving a contact resistance of ≈420 Ω µm, which also displays suppressed defect states in edge-contacted transistors.