Analysis of working principle of graphene integrated circuit

Scientists at IBM in the United States have developed the first integrated circuit made of graphene wafers, which is a step forward in the development of graphene computer chips. Scientists believe that this breakthrough may indicate that graphene wafers can be used instead of silicon wafers in the future.

Graphene is a two-dimensional crystal. The common graphite is formed by stacking a layer of planar carbon atoms arranged in a honeycomb order. The interlayer force of graphite is weak, and it is easy to peel off each other to form a thin film. Graphite sheet. When the graphite sheet is peeled off into a single layer, the single layer having only one carbon atom thickness is graphene. The latest discovery of graphene is the most effective way to prevent corrosion. Commonly used polymer coatings are easily scratched and have reduced protection properties; while graphene acts as a protective film, significantly slowing the corrosion rate of metals and making them more resistant to damage. Graphene is not only a new star in the electronics industry, but also a future for traditional industries. Its application direction: marine anti-corrosion, metal anti-corrosion, heavy anti-corrosion and other fields. Graphene has good thermal and electrical conductivity. However, the flexible graphene heat-dissipating film developed by using graphene can help existing notebook computers, smart phones, LED displays, etc., and graphene can greatly improve the heat dissipation performance.

The internal carbon atoms of graphene are arranged in the same manner as the graphite monoatomic layer by sp2 hybrid orbital, and have the following characteristics: carbon atoms have four valence electrons, and three of them generate sp2 bonds, that is, each carbon atom Contributing to an unbonded electron in the pz orbital, the pz orbital of the neighboring atom forms a π bond in a direction perpendicular to the plane, and the newly formed π bond is semi-filled. Studies have confirmed that the coordination number of carbon atoms in graphene is 3, the bond length between each two adjacent carbon atoms is 1.42 & TImes; 10-10 meters, the angle between the bond and the bond is 120 °. In addition to the cellular layered structure in which the σ bond is linked to other carbon atoms into a hexagonal ring, the pz orbital of each carbon atom perpendicular to the plane of the layer can form a large π bond (similar to the benzene ring) that penetrates the polylayer of the full layer. Thus has excellent electrical and optical properties.

This new approach developed by IBM researchers completely overturns the traditional silicon integrated circuit production process. This new approach takes the graphene transistor as the last step in the integrated circuit production step, thus preserving the original performance of the graphene device. The multi-platform graphene radio frequency receiver includes three graphene transistors, four inductors, two capacitors, and two resistors. The components in the circuit are integrated into a 0.6 square millimeter area and assembled on a 200 mm silicon production line. This graphene integrated circuit production line has unprecedented complexity and has the highest silicon CMOS device production capacity. This new production method also makes 3D heterogeneous integration on the silicon CMOS backbone possible.

In any wireless communication system, the receiver is a very critical component. The operating state of this integrated circuit consumes less than 20 mW of energy. At multiple GHz frequencies, the receiver in this integrated circuit is the most efficient of conversion among all graphene radio frequency integrated circuits. The test found that at 4.3 GHz signal strength, they successfully received and stored the three signals "I, B, M" without any distortion, thus confirming the feasibility of the application of graphene integrated circuits in the current wireless communication field. .