2D SEMICONDUCTORS PROGRAMME

PMs: Dr. CHI Dongzhi, IMRE; Dr. Johnson GOH, IMRE

Two-dimensional (2D) materials are only a few atoms thick (approx. 10-9 m) but yet exhibit great performance in various applications from digital/analog devices, optoelectronics to flexible electronics and biotechnology. Being void of external chemical bonds when isolated also enables their compatibility with existing conventional materials in the bulk. They represent a means towards further reduction in form factor and enhancement of performance in a future where the physical limit is being reached in today’s ever shrinking devices. We aim to impact the microelectronics industry by providing new perspectives and solutions based on 2D semiconductors to tackle problems present in nano-electronics beyond sub-10 nm node (e.g. mitigating short-channel effects), providing ubiquitous electronics based on ultra-thin large-scale flexible transparent electronics and opto-electronic devices.

Objective :


The strategic objective of this program is to (1) build world-class R&D capability in 2D materials and their applications, (2) create new materials knowledge and critical processing know-hows related to 2D materials, and (3) generate new scientific findings and important technological breakthroughs which can provide materials & processing solutions for future technology needs.

Approach :


The A*STAR 2D Semiconductors Pharos programme focus on investigating two most promising 2D semiconductor materials systems, namely atomically thin monolayer and few-layers of transition metal dichalcogenides (TMDCs, e.g., MoS2, WS2, etc) and black phosphorus (BP) with focus on (1) large area growth and preparation of 2D semiconductor materials and (2) novel devices/modules using 2D semiconductors and their applications taking advantage of their unique physical properties such as in-plane transport nature, immunity to short channel effect, strong light-matter interaction,  valley-spin interlocking together with additional favorable properties like being flexible, transparent, and transferable (to arbitrary substrates). The ultimate goal of this programme is to develop new science and breakthrough technologies that help us to realize a vertically integrated, monolithically and heterogeneously, smart nano-system based on 2D semiconductors, which is capable of sensing, data storage/processing/ computation, and communication.
2d-program-thrusts-and-key-milestones

Status and major achievements


2D semiconductors program was launched on 1 Jan 2016.  The main accomplishments to date include:

Technological achievements

  • Wafer-scale growth of of high quality monolayer MoS2 uniformly on 2 inch sapphire substrate by chemical vapor deposition (CVD) – ACS Nano, 2018, 12 (2), pp 1339–1349; 1 TD 
  • Demonstration of large scale 2D electronic devices and circuits (including  inverters and NAND logic gates) based on monolayer MoS2 grown by CVD – Adv. Electron. Mater. 2019, 1900393
  • Demonstrations of CVD-grown atomically-thin MoS2 memtransistors as electronic synapses for neuromorphic computing – Adv. Funct. Mater. 2019, 1901106  
  • Layer-by-layer uniform growth of mono-/few-layers MoS2 on 4 inch wafers by physical vapor deposition (PVD) and demonstration of memristive switching in the multilayer PVD MoS2 film  - Patents filed
  • Realization of substitutional p-type doping in WS2 monolayer and direct n- to p-type conduction channel conversion in WS2 FETs with atomic nitrogen treatment –ACS Nano, 2018, 12 (3), pp 2506–2513 
  • Wafer scale layer transfer – demonstrated 
  • Demonstration of room temperature operational 2D TMDC heterostructure for mid-IR photodetection and emission – Patent filed
  • Demonstration of hologram and flat lens with atomically thin 2D MoS2 – Patent filed

 

Scientific findings

  • Far out-of-equilibrium spin populations triggered giant spin injection into atomically thin MoS2 – Nature Physics 2019, 15, 347
  • Selective self-assembly of 2,3-diaminophenazine molecules on MoSe2 mirror twin boundaries –Nature Communications  (2019); https://doi.org/10.1038/s41467-019-10801-0 
  • Observation of Kondo effect in MoS2 and experimental & theoretical identification of vacancy-complex as the magnetic impurity source – a paper to be submitted to Nature Physics
  • Identification of anisotropic phonon group velocity as the origin of thermal transport anisotropy in black phosphorus – Advanced Materials (first published: 11 October 2018; https://doi.org/10.1002/adma.201804928)
  • Observation of tunable inverted gap in monolayer quasi-metallic MoS2 induced by strong charge-lattice coupling – Nature Communications 2017 Sep 7; 8(1):486. doi: 10.1038/s41467-017-00640-2
  • Demonstration of giant photoluminescence enhancement in tungsten-diselenide–gold plasmonic hybrid structures, Nature Communications volume 7, Article number: 11283 (2016)
2d-semiconductors-program-summary