Scientists in China and the US Achieve Breakthrough in Graphene Based Semiconductor Development.
In a pioneering achievement, researchers at Tianjin University and the Georgia Institute of Technology have successfully created a fully functional semiconductor using graphene. Walter de Heer and his team expanded upon existing fabrication techniques to introduce a bandgap into the 2D material while preserving graphene's robust and easily tunable properties.
While silicon has long been the cornerstone of modern semiconductor electronics, the latest silicon based technologies are facing challenges in meeting the increasing demands for higher computing speeds, lower power consumption, and more compact devices.
Graphene, first isolated in 2004, has emerged as a promising alternative to silicon. The one atom thick carbon sheet possesses advantageous properties, including high electron mobility, a robust yet lightweight structure, and excellent heat dissipation. The recent breakthrough in creating a functional graphene semiconductor opens new possibilities for advancing electronic devices beyond the limits of traditional silicon based technologies.
One Major Drawback
In contrast to traditional semiconductors, graphene lacks an inherent electron bandgap, an energy barrier crucial for enabling the conduction of electricity. This bandgap is what facilitates the creation of electronic switches, such as transistors, from semiconductor materials.
A persistent challenge in graphene electronics has been the absence of the requisite bandgap, preventing effective switching on and off at the desired ratio. Numerous attempts over the years have been made to address this issue through various methods. Previous studies explored engineering suitable bandgaps using techniques like quantum confinement and chemical modification of pure graphene. Unfortunately, these approaches have seen minimal success.
The process of refining graphene involved extensive learning to enhance its properties and devise methods for accurate property measurement. This intricate process took a considerable amount of time to achieve.
Spontaneous Growth
In their most recent study, researchers have successfully demonstrated the spontaneous growth of the semiconductor "epigraphene" with a bandgap on the surfaces of silicon carbide crystals, marking a groundbreaking achievement.
Prior investigations had indicated that, under high temperatures, silicon undergoes sublimation from the surfaces of these crystals, resulting in the formation of carbon-rich layers. These layers subsequently recrystallize into multi-layered epigraphene, possessing somewhat limited semiconducting properties.
Building upon this method, the team led by de Heer and Ma introduced an innovative annealing technique. By meticulously controlling the sample temperature and the rate of epigraphene formation, they produced a robust graphene layer characterized by macroscopic, atomically-flat terraces. Notably, the alignment of graphene atoms with the lattice of the silicon carbide substrate was achieved through this method.
Useful Bandgap
Through meticulous measurements, the research team established that this layer serves as an exceptional 2D semiconductor. It possesses the elusive and valuable bandgap that researchers have sought for decades, coupled with a high electron mobility.
The newly developed graphene semiconductor is remarkably robust, exhibiting 10 times the electron mobility of silicon. Moreover, it offers unique properties not found in silicon, creating an analogy of comparing electron mobility in silicon to driving on a gravel road, while the epigraphene resembles an electron freeway. This translates to enhanced efficiency, reduced heat generation, and the capability for higher electron speeds.
In addition to its outstanding performance, the team demonstrated the versatility of their epigraphene by doping it with various atoms and molecules to fine tune its electronic and magnetic properties. Furthermore, the material can be nanopatterned to further enhance its performance, a challenging feat with graphene grown on alternative substrates.
This groundbreaking technique holds the potential to revolutionize semiconductor manufacturing, offering a novel approach and marking a crucial initial step towards the development of a new generation of graphene based electronics.