Synthesis of large-area uniform Si2Te3 thin films for p-type electronic devices

Abstract

Two-dimensional (2D) p–n junctions are basic components of various functional devices. However, the shortage of natural p-type 2D semiconductors makes it difficult to achieve both p-type and n-type transport in high-performance multifunctional devices. Here, continuous and uniform p-type Si₂Te₃ thin films are grown on SiO₂/Si substrates, which are simultaneously used as an in situ Si source. Large-size 2D films with dimensions of ∼8 × 2 cm² are prepared for the first time using a reliable and simple chemical vapor deposition (CVD) technique. Film growth occurs via the vapor–liquid–solid mechanism, allowing the film thickness to be controlled by the substrate temperature. As the Si₂Te₃ film thickness increases from 3 to 8 nm, the bandgap decreases from 2.07 to 1.65 eV. Moreover, the directly grown thin films possess high crystallinity, showing electronic properties that are comparable to those of MoTe₂ crystals and MoS₂ films. Therefore, this large-area growth of p-type Si₂Te₃ enriches the 2D semiconductor library and opens up a new platform for the study of p-type Si₂Te₃, which has potential for application in p–n junctions.