Isotope Engineering: Advancements in 2D Semiconductor Design

Monday - May 6 2024, 14:19 UTC - 6 months ago

New research has shown the potential of isotope engineering to influence the optical and electronic properties of thin semiconductor materials. Led by scientists at Oak Ridge National Laboratory, this research has explored the effects of this technique in 2D materials, showcasing the ability to tune the optical bandgap of these materials through the use of heavier isotopes. This discovery has exciting implications for the development of advanced devices in microelectronics, solar cells, photodetectors, and computing technologies.

New research, led by scientists at the Department of Energy's Oak Ridge National Laboratory, has demonstrated the power of isotope engineering in influencing the optical and electronic properties of thin semiconductor materials. In recent years, semiconductors have played a crucial role in the development of advanced electronic devices and systems, making small changes in isotopic content a potential game-changer.

Traditionally, isotope engineering has been used to enhance the properties of bulk materials in three dimensions (3D). However, this new research is exploring its effects in the confined dimensions of atomically thin, two-dimensional (2D) materials. These ultrathin materials have promising potential for precise control over their electronic properties, making them prime candidates for use in sophisticated devices.

ORNL scientist Kai Xiao emphasized the exciting possibilities of this discovery: "We observed a surprising isotope effect in the optoelectronic properties of a single layer of molybdenum disulfide when we substituted a heavier isotope of molybdenum in the crystal, an effect that opens opportunities to engineer 2D optoelectronic devices for microelectronics, solar cells, photodetectors, and even next-generation computing technologies." .

Yiling Yu, a member of Xiao's research team, grew pure 2D crystals of molybdenum disulfide with isotopically different molybdenum atoms. The team noticed a small shift in the color of light emitted by these crystals when stimulated with light, the opposite of what would be expected in bulk materials. This result indicates a change in the material's electronic structure or optical properties, which the team traced back to the scattering of excitons (optical excitations) by phonons (crystal vibrations) in the confined dimensions of the 2D crystal.

The team further collaborated with theorists Volodymyr Turkowski and Talat Rahman at the University of Central Florida to understand this phenomenon. Their research showed that this scattering caused a red shift in the optical bandgap of the material, allowing for the tunability of absorption and emission properties. This ability to adjust the bandgap is crucial for designing new devices that can emit or absorb different colors of light.

ORNL's Alex Puretzky highlighted the potential benefits of this discovery: "Different crystals grown on a substrate can show small shifts in emitted color, caused by the article. This new understanding and use of isotope engineering can lead to advancements in fields such as microelectronics, solar cells, photodetectors, and computing technologies." .