Summary of SINGLE-ATOM TRANSISTOR ‘RECIPE’ SIMPLIFIES ATOMIC-SCALE FABRICATION
Researchers at NIST and the University of Maryland have created a reproducible method to fabricate single-atom transistors, marking the first time such devices are consistently produced with atom-scale geometric control. This technique utilizes quantum tunneling to regulate electron flow, enabling potential applications in quantum computing qubits. The process involves coating a silicon chip with hydrogen, using a scanning tunneling microscope tip to remove specific atoms, and then exposing the surface to phosphine gas so molecules bind only to the exposed sites.
Parts used in the Single-Atom Transistor Project:
- Silicon chip
- Hydrogen atoms
- Scanning tunneling microscope
- Phosphine gas (PH3)
Researchers at the National Institute of Standards and Technology (NIST) and the University of Maryland say they have developed a step-by-step recipe to produce single-atom transistors. by Rich Pell @ smart2zero.com
Transistors consisting of only several-atom clusters or even single atoms, say the researchers, promise to become the building blocks of a new generation of computers with unparalleled memory and processing power, but are notoriously difficult to fabricate in quantity. Now, using the new instructions, the researchers have become only the second in the world to construct a single-atom transistor and the first to consistently fabricate a series of single electron transistors with atom-scale control over the devices’ geometry.
The scientists demonstrated that they could precisely adjust the rate at which individual electrons flow through a physical gap or electrical barrier in their transistor. That strictly quantum phenomenon – known as quantum tunneling – only becomes important when gaps are extremely tiny, such as in the miniature transistors. Precise control over quantum tunneling is key, say the researchers, because it enables the transistors to become “entangled” or interlinked in a way only possible through quantum mechanics and opens new possibilities for creating quantum bits (qubits) that could be used in quantum computing.
To fabricate single-atom and few-atom transistors, the researchers relied on a known technique in which a silicon chip is covered with a layer of hydrogen atoms, which readily bind to silicon. The fine tip of a scanning tunneling microscope then removed hydrogen atoms at selected sites. The remaining hydrogen acted as a barrier so that when the researchers directed phosphine gas (PH3) at the silicon surface, individual PH3 molecules attached only to the locations where the hydrogen had been removed (see video).
Read more: SINGLE-ATOM TRANSISTOR ‘RECIPE’ SIMPLIFIES ATOMIC-SCALE FABRICATION
- What promise do single-atom transistors hold?
They promise to become building blocks for computers with unparalleled memory and processing power. - How did researchers control the flow of electrons?
They precisely adjusted the rate at which individual electrons flow through a physical gap or electrical barrier. - What phenomenon is key to this technology?
The strictly quantum phenomenon known as quantum tunneling is key because it enables entanglement. - Why is precise control over quantum tunneling important?
It allows transistors to become entangled or interlinked, opening possibilities for creating quantum bits. - What material covers the silicon chip initially?
A layer of hydrogen atoms that readily binds to silicon covers the chip. - How are hydrogen atoms removed from the chip?
The fine tip of a scanning tunneling microscope removes hydrogen atoms at selected sites. - What happens when phosphine gas is directed at the surface?
Individual PH3 molecules attach only to locations where the hydrogen had been removed. - Is this the first team to construct a single-atom transistor?
No, they are the second in the world to construct one but the first to consistently fabricate a series.
