A*STAR IMRE’s R&D Opens an Avenue for Wafer-Scale 2D Semiconductors
Lead author Dr Fu Wei and Principal Investigator Prof Johnson Goh showing a typical untreated sapphire wafer (left) and the successful 2D semiconductor film with oriented crystal domains grown on their surface engineered sapphire substrate (right)
Researchers at A*STAR’s Institute of Materials Research and Engineering (A*STAR IMRE) have achieved a significant breakthrough in the scalable fabrication of 2D semiconductors.
While epitaxial growth of 2D semiconductors is supposed to be guided by the underlying atomic order in the sapphire substrate, large-area growth has often resulted in randomly oriented polycrystalline structures. This limitation has posed a major challenge for the reproducibility and scalability of 2D quantum materials.
Led by Dr Fu Wei (Lead Author) and Prof Johnson Goh (Principal Investigator), the A*STAR IMRE team uncovered a key degradation mechanism in sapphire substrates - hydrolysis triggered by moisture exposure - that disrupts the atomic order necessary for aligned crystal growth. This issue is particularly pronounced in humid environments such as Singapore, where unintentional contact with moisture during transport or handling can gradually disorder the pristine alumina surface of sapphire. Through systematic ageing studies, the team demonstrated how hydrolysis leads to crystal misorientation and developed effective countermeasures to restore surface integrity.