12-inch growth of uniform MoS2 monolayer for integrated circuit manufacture.

Two-dimensional (2D) semiconductors, such as transition metal dichalcogenides, provide an opportunity for beyond-silicon exploration. However, the lab to fab transition of 2D semiconductors is still in its preliminary stages, and it has been challenging to meet manufacturing standards of stability and repeatability. Thus, there is a natural eagerness to grow wafer-level, high-quality films with industrially acceptable scale-cost-performance metrics. Here we report an improved chemical vapour deposition synthesis method in which the controlled release of precursors and substrates predeposited with amorphous Al2O3 ensure the uniform synthesis of monolayer MoS2 as large as 12 inches while also enabling fast and non-toxic growth to reduce manufacturing costs. Transistor arrays were fabricated to further confirm the high quality of the film and its integrated circuit application potential. This work achieves the co-optimization of scale-cost-performance metrics and lays the foundation for advancing the integration of 2D semiconductors in industry-standard pilot lines.

The Doping Effect on the Intrinsic Ferroelectricity in Hafnium Oxide-Based Nano-Ferroelectric Devices.

Hafnium oxide (HfO2)-based ferroelectric tunnel junctions (FTJs) have been extensively evaluated for high-speed and low-power memory applications. Herein, we investigated the influence of Al content in HfAlO thin films on the ferroelectric characteristics of HfAlO-based FTJs. Among HfAlO devices with different Hf/Al ratios (20:1, 34:1, and 50:1), the HfAlO device with Hf/Al ratio of 34:1 exhibited the highest remanent polarization and excellent memory characteristics and, thereby, the best ferroelectricity among the investigated devices. Furthermore, first-principal analyses verified that HfAlO thin films with Hf/Al ratio of 34:1 promoted the formation of the orthorhombic phase against the paraelectric phase as well as alumina impurities and, thus, enhanced the ferroelectricity of the device, providing theoretical support for supporting experimental results. The findings of this study provide insights for developing HfAlO-based FTJs for next-generation in-memory computing applications.

High-throughput screening and classification of layered di-metal chalcogenides.

Through employing the layered-crystal determination program based on the topology-scaling algorithm, 450 MmNnXx (M, N = metal elements, X = S, Se) layered di-metal chalcogenides (LDCs) are identified from the 1 602 011 crystalline materials known in two Material Genome databases (Materials Project and OQMD). Their structures are classified into three types, 104 compounds in standard MmNnXx homo-layered structures, 34 in MmXx1/NnXx2 hetero-layered structures and 312 in large-cation M-intercalated NnXx layered structures. 312 cation-intercalated LDCs are mostly composed of large cations such as K, Rb, Cs, Ba and Tl, and are not easy to be exfoliated into few-layer 2-dimensional (2D) structures because of the strong ionic bonding between the large cations and the negatively charged layers. In contrast, the homo-layered and hetero-layered structures may be exfoliated into stable few-layer 2D structures due to the weak inter-layer van der Waals interaction. The band structure screening identifies 34 direct- and 108 indirect-band-gap layered semiconductors from the 450 LDCs, and 24 of them have small in-plane effective masses and thus high mobility of hole or electron carriers. Two stable, direct-band-gap and high-mobility mono-layer semiconductors MgAl2S4 and ZnIn2S4 are found from group II-III2-VI4 LDCs. Furthermore, 83 LDCs composed of the magnetic metal elements are found, which provides new platforms for the search of 2D magnetic crystals similar to Cr2Ge2Te6 with intrinsic ferromagnetism. This work extends the search of layered materials from metal dichalcogenides to ternary chalcogenides and can serve as a map for the future discovery of novel 2D semiconductors and magnetic materials.