Wafer-scale growth of two-dimensional, phase-pure InSe

Two-dimensional (2D) indium monoselenide (InSe) has attracted significant attention as an ultrathin III–VI semiconductor with a combination of favorable attributes that are comparable to those of III–V semiconductors and van der Waals 2D transition-metal dichalcogenides. Nevertheless, there has been no demonstration of large-area synthesis of 2D InSe due to the complexity of the binary In-Se system and the difficulties in promoting lateral growth. Here, we report the polymorph-selective synthesis of epitaxial 2D InSe by metal-organic chemical vapor deposition (MOCVD) over 2-in wafers. We achieve polymorph-selective epitaxial growth of InSe on c-plane sapphire via flow modulation to control the Se/In ratio. The layer-by-layer growth allows thickness control with tunable optical properties comparable to those of bulk crystals. We also demonstrate gate-tunable electrical transport with a field-effect mobility comparable to that of single-crystalline flakes. These results indicate that InSe grown by MOCVD could be an effective channel material for back-end-of-line integration in logic transistors. [Display omitted] •First polymorph-selective epitaxy of 2D InSe thin film is demonstrated•Flow-modulation technique enables selective nucleation of InSe instead of In2Se3•Layer-by-layer growth mode enables production of InSe with different thicknesses•As-grown InSe shows electronic and optical properties similar to exfoliated flakes Two-dimensional (2D) InSe has attracted attention for next-generation electronic devices due to its atomically thin structure with a low effective mass and high thermal velocity among known 2D semiconductors. However, scalable synthesis of high-quality InSe with high phase purity remains unachieved. This study introduces a pulsed-precursor, metal-organic chemical vapor deposition technique for the epitaxial synthesis of InSe on c-plane sapphire. Pulsing precursors during the synthesis process effectively controls the In-to-Se ratio, thereby widening the growth window for pure InSe instead of In2Se3. The resulting high-quality InSe demonstrates promising optical and electrical properties. This highlights the potential of our synthesis technique for achieving future high-performance optoelectronic materials, including various 2D III–VI compound semiconductors at temperatures below 500°C. Growth of two-dimensional (2D) indium monoselenide (InSe) over 2-in wafers is demonstrated using pulsed metal-organic chemical vapor deposition (MOCVD) at