2D Materials First Planar, Silicon-Free Computer at the Atomic Level

Related Vendors

FAULHABER Drive Systems

Wuxi InfiMotion Technology Co., Ltd.

Researchers at Penn State University in the USA have developed a complete CMOS computer made entirely of 2D materials for the first time, capable of performing simple computational operations.

Silicon, through its miniaturization, has enabled advances in semiconductor technology but is increasingly reaching the limits of what is physically possible. This drives the exploration of new materials to meet the future demand for ever more compact and efficient electronic systems at the lowest possible cost. Two-dimensional (2D) materials, which are only a few atomic layers thick and simultaneously possess high charge carrier mobility, represent a promising alternative in research.

Researchers at Penn State University have used two such 2D materials to develop, in a world first, the first computer that is only a few atomic layers thick yet can still perform simple operations. The research team used 2D molybdenum disulfide (MoS₂) for the n-channel devices and tungsten diselenide (WSe₂) for the p-channel to build the complementary structures with a thickness of one atom.

These materials are key to building transistors with structures smaller than 1 nm, as the researchers state in the accompanying study in the journal Nature. The successful 2D implementation represents a significant step towards thinner, faster, and more energy-efficient electronics.

The work is an advancement of previous research on simple computers using carbon nanotubes (CNT) and a flexible 2D-PMOS machine built with MoS₂ transistors at the Vienna University of Technology. 2D materials were recently also used for embedded high-performance memory. The development is independent of the creation of the first planar 32-bit RISC-V processor, which also based on 2D molybdenum disulfide (MoS₂) and was introduced by Chinese researchers at the end of April in the journal Nature.

2D Chip with Almost 6,000 Transistors

Researchers Develop Atomically Thin 32-Bit RISC Processor

Computer Construction

"We have, for the first time, demonstrated a CMOS computer entirely constructed from 2D materials, combining large-area grown molybdenum disulfide and tungsten diselenide transistors," says Saptarshi Das, Ackley Professor of Engineering and Professor of Engineering Science and Mechanics at Penn State, who led the research. The developed system includes an SRAM cell with six transistors and pull-up and pull-down transistors, as well as an arithmetic logic unit. The resulting computer was capable of executing a five-stage RSSB instruction (Reverse Subtract and Skip if Borrow) using five separate OISC structures (One Instruction Set Computer).

The team utilized metal-organic chemical vapor deposition (MOCVD) in the Materials Innovation Platform of the 2D Crystal Consortium (2DCC-MIP) to grow large layers of molybdenum disulfide and tungsten diselenide, enabling the production of more than 1,000 transistors of each type. By tuning the device fabrication and post-processing steps, they were able to adjust the threshold voltages of both the n-type and p-type transistors, which allowed for the construction of fully functional CMOS logic circuits at 3 V.

"Our 2D-CMOS computer operates at low supply voltages with minimal power consumption and can perform simple logical operations at frequencies up to 25 kHz," said Subir Ghosh, a doctoral student at Penn State who, along with Das, led the research.

The frequency was limited by parasitic capacitances, along with an extremely low power consumption in the picowatt range and a switching energy of up to 100 pJ.

"We also developed a computational model calibrated with experimental data that accounts for variations between the devices to project the performance of our 2D CMOS computer and compare it to state-of-the-art silicon technology," says Ghosh. This involved projecting the performance of the one instruction set computer and comparing it with the most advanced silicon technology, using a BSIM-BULK model compatible with the industry-standard SPICE.

Transistor Development With 2D Materials is Still in its Infancy

Ghosh admits that there is still much room for further optimization. The system is a proof of concept, and there is currently no practical application for the simple computer. Nevertheless, this work represents an important milestone in the use of 2D materials to advance the field of electronics.

His colleague Das also confirms that more work is needed to further develop the 2D CMOS computer approach for widespread application. However, he also emphasizes that the research field is evolving rapidly compared to the development of silicon technology: "Silicon technology has been in development for about 80 years, whereas research on 2D materials is relatively young and only really took off in 2010," says Das. "We anticipate that the development of computers from 2D materials will also be a step-by-step process, but compared to silicon technology, this is a major leap forward." (sg)