Researchers are harnessing the power of tiny defects in an incredibly thin material to one day make computer chips faster and more efficient than traditional silicon semiconductor platforms.
“All of our existing electronic devices use chips made of silicon, a three-dimensional material,” said Shoaib Khalidphysicist at the Princeton Plasma Research Laboratory, in a statement“Today, many companies are investing heavily in chips made of two-dimensional materials.”
This type of “two-dimensional” material, known as a transition metal dichalcogenide (TMD), can be just a few atoms thick. Computer chips made from these ultrathin semiconductors could enable the development of smaller, faster devices by packing much more processing power into a smaller area.
In a study published May 24 in the journal 2D MaterialsKhalid’s team investigated whether using TMD instead of silicon could be a solution to the idea that innovation with silicon-based chips may be reaching its peak.
The thinnest TMDs are only three atoms thick and are arranged like a sandwich. The “bread” is made of chalcogen atoms, elements in group 16 of the periodic table, such as oxygen or sulfur. Transition metal atoms, from groups 3 to 12, make up the “filling.”
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Scientists studied whether they could exploit tiny, atom-sized imperfections, called defects, in slightly thicker TMDs.
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Although most of the atoms in the TMD are arranged in an orderly and regular fashion, occasionally an atom is missing or stuck in a place where it doesn’t belong. Despite their name, defects aren’t necessarily a bad thing, the scientists said in the study. For example, some defects make TMDs more electrically conductive.
To take advantage of the positive effects of defects and reduce their negative consequences, scientists needed to understand how defects arise and how they affect material performance. As part of the study, Khalid’s team determined which types of defects form most easily in TMDs and studied how these defects shape the material’s properties.
First, the team looked at defects where one of the chalcogen atoms was missing. study Researchers have shown that a TMD material called molybdenum disulfide unexpectedly emits infrared light when illuminated. Khalid’s team found that the infrared light emission was triggered by the movement of electrons bound to the space where the missing chalcogen should be.
“Our work provides a strategy to study the presence of these vacancies in bulk TMDs,” Khalid said in the statement. “We explained the previous experimental results shown in molybdenum disulfide, and then predicted a similar thing for other TMDs.”
Next, the researchers studied a type of defect in which an extra hydrogen atom is squeezed between two neighboring transition metal atoms. Hydrogen is a common impurity that appears in TMDs during their formationThe extra hydrogen atoms give many, but not all, TMD materials a slight negative charge, turning them into “n-type” semiconductors.
Computer chips rely on a combination of n-type semiconductors and positively charged p-type semiconductors. Scientists already knew that some TMD materials could act as n-type semiconductors, but the new study explains where the extra negative charge comes from.
Understanding how these defects affect TMD performance could help researchers create next-generation computer chips, the scientists said in the study. Although TMD chips are not yet ready for commercial use, Companies explore ultra-thin TMD chips to cope with energy-intensive AI operations.
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