Silicon has formed the backbone of our electronic devices for decades, but as gadgets get smaller and are tasked with performing more demanding applications, alternative semiconductors are urgently needed.
Jing Wu, a Research Scientist at A*STAR’s Institute of Materials Research and Engineering (IMRE), said that because most conventional semiconductors are bulk materials, they are heavily impacted by the short channel effect during miniaturisation.
“At the nanometre length scale, when the device’s channel length is comparable to its thickness, the short channel effect adversely impacts performance by causing leakage and interference,” said Wu, adding that this results in unpredictable and error-prone electronics.
Together with researchers from the Hong Kong Polytechnic University, Fudan University, Nanjing Normal University, National Institute for Materials Science and the National University of Singapore, Wu explored the potential of ultra-thin, two-dimensional (2D) semiconductors made from MoS2 as silicon replacements for next-generation electronics. Standing in the way of the commercialisation of 2D semiconductors, however, is the inherent limitation of their low carrier mobility due to the high density of phonon scattering.
Much like how traffic jams lengthen the rush hour commute, carrier mobility impacts how quickly electrons can zoom through a material under an electric field, explained Wu. “When carrier mobility is low, electronic devices respond and operate more slowly, which significantly limits applications in high-performance computing and communication devices,” said Wu.
To resolve this shortcoming, the team counterintuitively introduced lattice distortions into MoS2 as a means of improving charge carrier mobility by reducing electron-phonon scattering. They used bulged substrates which created ripples in the material, thereby challenging the current school of thought that smooth, homogenous materials would more likely reduce electron scattering.
Instead, their investigation revealed that the rippled MoS2 enhanced carrier mobility by two orders of magnitude, reaching room-temperature mobility levels of about 900 cm2V-1s-1 (exceeding that of flat MoS2 at about 200 to 400 cm2V-1s-1).
Wu said that this enhancement holds great promise for creating tomorrow’s high-performance and low-power electronics, super-efficient thermoelectric devices for energy harvesting and much more.
“Our counterintuitive approach on rippled MoS2 is effective and universally-applicable to other 2D semiconductors, which facilitates the development of emerging technologies where high-speed, low-power and reliable charge transport are critical,” said Wu.
The team continues to make waves in the field with in-depth investigations on how fine-grained ripple structures influence the performance and potential of 2D semiconductors.
The A*STAR-affiliated researchers contributing to this research are from the Institute of Materials Research and Engineering (IMRE).