9 Unexpected Ferroelectricity in Untwisted Heterobilayers for Next-Generation Nanoelectronics 2D materials with out-of-plane (OOP) ferroelectricity and piezoelectricity are highly desirable for ultrathin ferro- and piezoelectronic devices. Prof. LAU Shuping has demonstrated unexpected OOP properties in untwisted, commensurate, and epitaxial MoS2/WS2 heterobilayers synthesized by scalable one-step chemical vapour deposition (CVD), obtaining the modulation of tunnelling current by 1,000 times in ferroelectric tunnel junction devices. This discovery facilitates new ultrathin ferroelectric devices for next-generation nanoelectronics. One Photon Generates Multiple Electron-Hole Pairs for Better Light Harvesting The photocurrents in solar cells, photovoltaics and photodetectors rely on the conversion of photons into electron-hole pairs. Dr LI Mingjie’s group recently discovered the multiple exciton generation (MEG) effects in tin-lead halide perovskite nanocrystals and their devices by the generation of multiple electron-hole pairs from a single high-energy photon. Outstanding photon-charge conversion efficiencies were achieved, for example, MEG efficiency up to 87%, photocurrent internal quantum efficiency >100%. This effect is particularly useful for practical applications of perovskite solar cells in the future. Impact Stories Ripples Boost Charge Carrier Mobility for Next-Generation Field-Effect Transistors 2D semiconductors often suffer from strong phonon scattering and thus show low carrier mobility at room temperature. Dr YANG Ming developed a new approach to improve carrier mobility by introducing ripples into MoS2 nanofilm and investigating the physical mechanisms behind. The ripples enhanced the room-temperature mobility significantly with a record-high value of ~900 cm2 V-1 s-1, exceeding the phonon-limited mobility of flat MoS 2. This enables high-performance room-temperature field-effect transistors and thermoelectric devices for next-generation nanoelectronics. One Material, Three Phases, New Structure for In-Memory Computing Material structure, transport mechanism and measurement setup of rippled MoS2 based 2D device by Dr Yang’s group. Material structure and model of CVD-grown MoS2/WS2 heterobilayers by Prof. Lau’s group. Phase-controlled synthesis of large-area 2D In2Se3 films and the application of in-plane heterophase junctions in field-effect transistor memory devices by Dr Zhao’s group. Schematic diagram of black phosphorus ultrathin films and top-gated Field-Effect Transistor (FET) arrays. Ferroelectric field-effect transistors hold the key to newgeneration logic-in-memory devices. Dr ZHAO Jiong and his co-workers discovered a new method to synthesize centimetre-size 2D In2Se3 with all three different phases including β, β', and α phases and demonstrated field-effect transistors with improved non-volatile memory device performance. This opens up numerous opportunities for developing novel structures and concepts for future FE electronics as well as logic-in-memory devices. Conceptual diagram and working principle of multiple exciton generation (MEG) effects in tin–lead halide perovskite nanocrystals for higher light-energy conversion by Dr Li. The First Method to Grow Black Phosphorus into Large-Area Ultrathin Films Black phosphorus (BP) is a layered semiconductor most promising for transistor devices at atomistic thickness. However, the growth of large-area BP is still lacking. Prof. HAO Jianhua’s group has invented a new method using pulsed laser deposition to grow ultrathin BP at centimetre scale. Furthermore, they have fabricated large-scale field-effect transistor arrays on BP films, yielding appealing hole mobility of up to 213 and 617 cm2 V−1 s-1 at 295 and 250 K, respectively. This work represents a major cornerstone for the BP-based IC industry.
RkJQdWJsaXNoZXIy Mjc5OTU=