Chinese Researchers Achieve Wafer-Scale Synthesis of P-Type 2D Semiconductor

Researchers led by Professor Ren Wencai at the Institute of Metal Research of the Chinese Academy of Sciences have successfully produced wafer-scale monolayer MoSi₂N₄ single crystals. This breakthrough provides a reliable p-type 2D semiconductor, filling a long-standing gap in the materials required for next-generation electronics.

To achieve this, the team utilized a specialized chemical vapor deposition (CVD) method on copper single crystals oriented as Cu (111) and enriched with molybdenum and silicon atoms. This approach allowed the researchers to overcome previous limitations that typically resulted in polycrystalline films, instead producing high-crystallinity monolayers. The resulting MoSi₂N₄ film exhibits an intrinsic carrier mobility of 154 cm² V⁻¹ s⁻¹. Furthermore, field-effect transistor (FET) arrays fabricated from the film demonstrated a current density of up to 17.96 µA µm⁻¹ at a 1-micrometer channel length and an on/off ratio of 3.8 ± 1.4 × 10⁶.

The CMOS Bottleneck

As traditional silicon-based electronics approach the 5nm limit, the industry faces severe physical barriers. One of the most pressing issues is electrical leakage caused by short-channel effects, which occur as transistors shrink to atomic scales. Two-dimensional (2D) materials have long been proposed as the solution because their extreme thinness allows for better electrostatic control.

However, a fundamental imbalance has hindered progress. While n-type 2D semiconductors, such as MoS₂ and WS₂, have already been developed at a wafer-scale, the industry lacked a high-performance p-type equivalent. Because complementary metal-oxide-semiconductor (CMOS) circuits—the foundation of almost all modern processors—require both n-type and p-type materials to function, the absence of a scalable p-type semiconductor has stalled the creation of fully 2D integrated circuits.

Implications for Microprocessors

This development resolves a major technical hurdle by providing a scalable, high-quality p-type material. By enabling the pairing of MoSi₂N₄ with existing n-type 2D materials, the research paves the way for the development of fully 2D commercial microprocessors. These circuits could potentially shrink beyond the physical limits of silicon while maintaining stability and performance, offering a path toward continued scaling in semiconductor density.

Future Outlook

The versatility of the synthesis method was further demonstrated as the researchers successfully applied the same CVD technique to create wafer-scale monolayer WSi₂N₄ single crystals. The ability to produce multiple types of these crystals suggests a broader platform for 2D material engineering. The next critical steps will involve integrating these p-type monolayers into complex circuit architectures to verify their performance in real-world CMOS configurations.