The Shrinking Transistor

In 1965, Gordon Moore famously predicted that the number of transistors on an integrated circuit would double about every two years. While the increase still roughly follows that prediction, this trend will eventually slow because shrinking transistors any further will…

In 1965, Gordon Moore famously predicted that the number of transistors on an integrated circuit would double about every two years. While the increase still roughly follows that prediction, this trend will eventually slow because shrinking transistors any further will introduce quantum-mechanical effects, such as tunneling, which can degrade performance. Now, Ye-Fei Li and Zhi-Pan Liu of Fudan University, China, have identified two semiconductor materials that should be robust to tunneling when formed into a transistor structure that has lateral dimensions as small as one nanometer.

In their study, Li and Liu used a machine-learning method to simulate thousands of so-called field-effect transistors. These transistors combine a semiconducting layer, usually silicon ( Si), together with an insulating layer, usually silicon dioxide ( SiO2), to modulate current flow. The duo used a different combination of lattice orientations for Si and SiO2 to figure out which performed the best on nanometer scales. Of the 2497 simulated lattice structures of Si and SiO2 that they considered, the duo found that only 40 contained a pattern that repeated itself every nanometer. Of those 40, only 10 were stable—their interfacial structure had a similar energy to their bulk structure—a requirement for a robust transistor. They also found that the orientation of the two materials relative to each other was key to effective device operation. Ultimately, they identified two systems, Si(210)∕SiO2(102) and Si(211)∕SiO2(112), that minimized quantum tunneling effects. The researchers now plan to use their technique to study other transistor materials, such as gallium nitride and silicon carbide. Transistors built from those materials can withstand higher temperatures and handle higher voltages than silicon ones, making them ideal for use in technologies such as electric cars and trains.–Monica BobraMonica Bobra is a research scientist and a contributing editor for Sky & Telescope magazine.ReferencesY. F. Li and Z. P. Liu, “Smallest stable Si/SiO2 interface that suppresses quantum tunneling from machine-learning-based global search,” Phys. Rev. Lett. 128, 226102 (2022).Smallest Stable Si/SiO2 Interface that Suppresses Quantum Tunneling from Machine-Learning-Based Global SearchYe-Fei Li and Zhi-Pan LiuPhys. Rev. Lett. 128, 226102 (2022)Published June 3, 2022Subject AreasQuantum PhysicsElectronicsSemiconductor PhysicsRelated ArticlesQuantum PhysicsA Parametric Oscillator for PhononsMay 26, 2022A newly demonstrated device could lead to the creation of entangled pairs of phonons. Read More »Fluid DynamicsLooking Inside the Superfluid Helium-3 UniverseMay 25, 2022A camera that can capture the internal structure of superfluid helium-3 will improve our understanding of the turbulent motion of quantum fluids. Read More »PhotonicsExplaining Asymmetric Emission from Quantum DotsMay 20, 2022A new experiment on the emission spectrum of quantum dots in photonic-crystal microcavities supports a recently proposed theory of cavity quantum electrodynamics. Read More » More Articles