Chinese researchers have developed a technology for producing ultra-smooth metal alloys. This material has become an ideal substrate for producing high-quality graphene, which opens up new opportunities for creating effective nanoelectronics.
A group of scientists from Peking University and other scientific centers in China has solved a key problem in materials science. They managed to create large single-crystal films from alloys copper, nickel, platinum and palladium with an almost perfect, atomically smooth surface.
The main difficulty in creating such materials was the high-temperature annealing process required to uniformly mix the atoms of different metals. When heated above 1000 °C, defects appeared on the surface of the film – microscopic holes and irregularities that made the material unsuitable for use.
The researchers found that this problem is caused by differences in the surface energy of the metals. They proposed a simple but effective solution: applying metals in a strictly defined order. First, a layer of high surface energy metal (such as nickel) is deposited on the sapphire substrate, followed by a layer of low energy copper on top. When heated, the top layer stabilizes the surface, preventing the formation of defects, resulting in a perfectly smooth, homogeneous alloy.
Using this method, scientists obtained single-chip films with a diameter of 4 inches (about 10 cm) with a minimum number of defects. Thousands of ruptures occurred on such plates without surface energy control, but only dozens with the new technology.
The main practical achievement was the use of a ternary copper-platinum-nickel alloy as a substrate for the production of graphene. Typically, at high temperatures, graphene develops folds and irregularities due to the difference in thermal expansion with the base, which deteriorates its electronic properties. The new substrate made it possible to reduce the growth temperature of graphene to 850 °C and almost completely suppress the formation of folds.
As a result, homogeneous graphene without wrinkles was obtained over the entire area of the wafer. Its electrical resistance turned out to be not only low, but also extremely uniform over the entire surface, which critical for mass production of electronic components.
The development of Chinese scientists represents a significant breakthrough in materials science. The creation of perfectly smooth metal substrates paves the way for the industrial production of high-quality graphene for the next generation of nanoelectronics, quantum devices and sensors.
Source: Global Energy
Image: Global Energy
