Redefining energy efficiency in data processing, two-dimensional semiconductors with thousands of transistors are available

Researchers have created the first memory processor based on two-dimensional semiconductor materials, containing more than 1,000 transistors, a major milestone on the road to industrial production. Photo credit: Alan Herzog/École Polytechnique Fédérale de Lausanne

According to the latest issue of "Nature Electronics", researchers from the Ecole Polytechnique Fédérale de Lausanne in Switzerland have proposed a memory processor based on molybdenum disulfide, which is dedicated to one of the basic operations in data processing: vector matrix multiplication. This kind of operation is ubiquitous in the implementation of digital signal processing and artificial intelligence models, and its efficiency improvement can save a lot of energy for the entire information and communication industry.

The new processor combines 1,024 components onto a one-centimeter-square chip. Each element contains a 2D molybdenum disulfide transistor along with a floating gate to store charge in its memory to control each transistor's conductivity. Coupling processing and memory in this way fundamentally changes the way processors perform computations.

The researchers note that by setting the conductivity of each transistor, they can apply a voltage to the processor and measure the output, performing analog vector-matrix multiplication in one step.

The choice of molybdenum disulfide played a crucial role in the development of memory processors. Unlike silicon, the most widely used semiconductor in today's computer processors, molybdenum disulfide forms a stable monolayer only 3 atoms thick that interacts only weakly with its surrounding environment. Its thinness offers the potential to produce extremely compact devices. In 2010, the research team created the first single molybdenum disulfide transistor using a single layer of material peeled off a crystal using Scotch tape.

The key advancement from a single transistor to more than 1,000 transistors has been the quality of the materials that can be deposited. After extensive process optimization, the team can now produce entire wafers evenly covered with a homogeneous layer of molybdenum disulfide. This allowed them to design integrated circuits on computers using industry-standard tools and convert those designs into physical circuits, opening the door to mass production.

Molybdenum disulfide is somewhat like graphite and can be used as a lubricant or as a thin film on surfaces with tape. Because of its "two-dimensional" semiconductor properties, molybdenum disulfide films are expected to break through the bottleneck of transistor miniaturization and build new chips that are faster, lower power consumption, flexible and transparent. In recent years, the world has made continuous breakthroughs in the preparation of single-layer molybdenum disulfide, and has continued to explore the limits of wafer quality and device performance. China is at the forefront in this direction. In the future, this may be used to develop chips and displays that consume very little, are wearable and can be bent at will.