Using low-energy ion implantation, researchers have reported a new method to construct 2D lateral p-n junctions paving the way for applications of more energy-efficient and powerful semiconductor devices (Image: Ya-Ping Lin & Qian Zhang/School of Engineering Science/Kyoto University)
The ultimate defeat of silicon
The semiconductor industry is under siege as it grapples with the costly and complex technology changes to shrink the feature size of silicon-based transistors, which is fast approaching its physical limits. The answer is, arguably, in the field of atomic manufacturing, where materials are processed and controlled with precision at the atomic scale.
Ultimately, this power-saving melting level enables a vastly lower power requirement per logic element and so greatly increase the arithmetic potential of those chips. Graphene and transition metal dichalcogenides are 2D materials, have been proposed as alternative options to overcome the issues with current silicon-based devices. Nevertheless, the practical utilization of these 2D materials is limited because of the difficult design of high-performance p-n-junction.
2D Lateral p-n Functionality Unleashed
P-N junctions represent the elementary building block of optoelectronic devices essential in our information area. Prior work in this area had been concentrated on making 2D vertical p-n junctions, but these had lower carrier mobility as a result of the van der Waals gap and stacking brought about by impurities.
The breakthough was the realization of 2D lateral p-n junctions, which can alleviate these issues. To date, maintaining the ultraprecise control and high-quality fabrication of 2D lateral p-n junctions has been an immense undertaking.
In contrast to the vertical p-n junctions, it has been impossible to build 2D lateral p-n junctions without a metal gate until the researchers from Wuhan University developed a unique technique based on low-energy ion implantation. It preserves the merits of traditional ion implantation, such as tunable dopants at controllable depth, and enables damage-free high-dose doping on the scale of atomic monolayers of 2D materials by preventing high-energy ion bombardment that can cause damage to or pass through ultrathin 2D materials.
Conclusion
It was a remarkable breakthrough with low-energy ion implantation to achieve 2D lateral p-n junctions, bringing closer the full utilization of this family of 2D semiconductor materials at their potential. With this discovery, new technologies that require efficient and strong electronic and optoelectronic devices will become possible in the near future. The technique could present one of the greatest advancements in semiconductor technology, as it is capable of application across numerous 2D materials.
