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Tunnelling applications
Intermediate
Scanning tunnelling microscopes and nuclear fusion in stars.
Scanning tunnelling microscopes (current ∝ e^{−2κd} for atomic resolution), tunnel diodes, flash memory and fusion in the Sun.
STM sees individual atoms.
Current is extremely sensitive to the gap.
In more detail
Tunnelling is used in devices such as scanning tunnelling microscopes, tunnel diodes and flash memory. It also drives processes such as nuclear fusion in stars.
Real-world uses
- Scanning tunnelling microscopes map surfaces at the atomic scale.
- Flash memory stores data by tunnelling electrons into floating gates.
- Scanning tunnelling microscopes image individual atoms by measuring the current that tunnels between a tip and a surface.
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Frequently asked questions
How does an STM work?
A tip is brought near a surface, and the tunnelling current depends sensitively on the distance.
Does tunnelling occur in the Sun?
Yes, protons tunnel through the Coulomb barrier to fuse in stellar cores.
Why is the current so sensitive to distance?
The tunnelling probability falls exponentially with the gap, so a tiny change in distance changes the current a lot.
Related topics in Quantum Mechanics
Free particle · Finite potential well · Quantum tunnelling · Alpha decay as tunnelling · Quantum harmonic oscillator · Zero point energy