The King Abdullah University of Science and Technology (KAUST) 's first demonstration of a functional microchip integrating atomically thin two-dimensional materials with exotic properties heralds a new era in microelectronics, a breakthrough that demonstrates the potential of two-dimensional materials to expand the functionality and performance of microchip-based technologies. 

Since scientists first produced thin layers of atomic-scale graphite - graphene - in 2004, there has been intense interest in advanced and novel applications of this material due to its peculiar and promising physical properties. But despite two decades of research, functional microdevices based on these two-dimensional materials have proved difficult to achieve because of the challenges in manufacturing and processing such fragile films. 

Inspired by the Lanza Laboratory's recent achievements in functional two-dimensional films, the KAUST led collaboration has now produced and demonstrated a two-dimensional based microchip prototype. 

"Our motivation is to improve the level of technical readiness for electronic devices and circuits based on two-dimensional materials by using traditional silicon-based CMOS microcircuits as the foundation and standard semiconductor manufacturing techniques, "Lanza said. However, the challenge is that synthetic two-dimensional materials can contain local defects, such as atomic impurities, that can cause small devices to fail. And it's very difficult to integrate two-dimensional materials into a microchip without damaging it." 

The team optimized the chip's design to make it easier to manufacture and minimize the effects of defects. They did this by making standard complementary metal oxide semiconductor (CMOS) transistors on one side of the chip and channeled the interconnect to the bottom, where the 2D material could be reliably transferred in small pads less than 0.25 microns in diameter. 

"We produced a two-dimensional material -- hexagonal boron nitride, or h-BN, on copper foil -- and transferred it to a microchip using a low temperature wet process, and then we formed electrodes on it through traditional vacuum evaporation and photolithography, which we have in-house, "Lanza says. In this way, we produce a 5×5 single transistor/single memory cell array connected by a horizontal bar matrix. 

The curious property of two-dimensional h-BN is that it is only 18 atoms, or six nanometers, thick, making it an ideal "memory" -a resistance element whose resistance can be set by the applied voltage. In this 5 x 5 specification, each tiny memory pad is connected to a dedicated transistor. This provides the fine voltage control needed to give the memory high performance and high reliability as a functional device over thousands of cycles, in this case operating as a low-power neural network element. 

"With this flagship breakthrough, we are now talking to leading semiconductor companies to continue in this direction, "Lanza said. We are also considering installing our own wafer-scale industrial processing system of two-dimensional materials at KAUST to advance this capability."