5 ms·

Title claims "transistor"; article and infographic says that only "diode" was actually demonstrated.

posterboy 9y ago
> “We’ve built a molecular-scale transistor ... A co-author makes bolder claims. I guess in context, the meaning is different, more of a metaphor. And even though, diodes can form some logic gates (diode-logic). > ... simple chemical changes within a molecule, can have a profound influence on the electronic structure of molecules, leading to different electrical properties.” But what's really interesting is the size of 14 atoms in the core of the molecule. How does that compare to 14 nm feature-sizes of different FET-technologies?
- ISL 9y ago
  A rule of thumb: a hydrogen atom is 0.1 nm in diameter.
  - SapphireSun 9y ago
    A caveat to keep in mind, diatomic hydrogen is not 0.2. EDIT: Actually the van der wahl diameter of Hydrogen is about 240pm. 0.12nm is about the radius.
- aeleos 9y ago
  In the article it says that the cluster is around 0.5 nanometers in diameter.
  - logfromblammo 9y ago
    Article said that the inorganic core was 14 atoms. The graphic showed a much larger organic molecule wrapped around the core. It is unclear whether 0.5 nm refers to the inorganic core or the entire molecular complex. It is also possible that the organic molecule changes geometry to open or close the conductive channel, so it could have variable diameter.
castis 9y ago
Im just getting started with hardware electronics so forgive me if this is way off. Also, not to defend the title... Is a standard transistor just two diodes with similar sides facing each other?
- deleted 9y ago
  [deleted]
- Retra 9y ago
  I would expect two diodes facing each other would just act like one diode with two connections. A transistor uses one input to control the flow through another path. So something more like a diode that is 'programmable' by another diode.
- bdamm 9y ago
  In terms of P/N/P layering I believe (from my limited understanding) that what you're saying is generally true. However, given two diodes you can't make a transistor, so it is not equivalent to say that a transistor is just two diodes. Especially at this ultimate scale, proving a diode is not the same as proving a transistor. The mechanism of semi-conductivity is not the same at 0.5nm as it is at 14nm.
- logfromblammo 9y ago
  A standard field-effect transistor has four connections: gate, base, source, and drain. In MOSFET logic circuits, two of those connections are wired together, depending on whether it is NPN or PNP, and which side of the circuit it is on. Applying voltage between gate and base affects the size of the conductive channel between source and drain, like pinching off the flow from one garden hose by wrapping another hose around it. If you slap two diodes together, you still need to send current through it "sideways" to see a transistor effect.
- noobiemcfoob 9y ago
  Unless I'm mistaken, that would act as a capacitor. A transistor has a slightly more complicated doping pattern with a gate as shown here: http://cdn4.explainthatstuff.com/fet1.gif http://cdn4.explainthatstuff.com/fet1.gif
brudgers 9y ago
I am not an electrical engineer. My understanding is that in theory two diodes can provide (at least some of) the functionality of a transistor. In practice, using current semiconductor technology, this is impractical/impossible. My reading of the article is the claim that it is possible to provide the behavior of transistors with the single molecule. That is not the same as claiming a single molecule mechanism uses the same technology as current integrated circuits. The analogy I would draw is that transistors have many of the same behaviors as vacuum tubes...or more perhaps more visually the same behaviors as valves in the British usage. Of course I may be completely misunderstanding the article and it's claims, but that is how I resolved the various confusing implications.
- hatsunearu 9y ago
  >My understanding is that in theory two diodes can provide (at least some of) the functionality of a transistor. very false. bipolar junction transistors have the structure of two diodes back to back but just because you sandwich two diodes doesn't mean it's automatically a transistor. the middle material has to be lightly doped and must be also very thin, or else it won't "trans" much.
  - brudgers 9y ago
    Sorry for not being as clear as I would have liked. I am not sure that current semiconductor approaches are relevant to the work of the lab. The analogy may be that the lab is developing a technical approach that is different from current techniques in a manner similar to the way semiconductors were different from vacuum tube techniques.

> “We’ve built a molecular-scale transistor ... A co-author makes bolder claims. I guess in context, the meaning is different, more of a metaphor. And even though, diodes can form some logic gates (diode-logic). > ... simple chemical changes within a molecule, can have a profound influence on the electronic structure of molecules, leading to different electrical properties.” But what's really interesting is the size of 14 atoms in the core of the molecule. How does that compare to 14 nm feature-sizes of different FET-technologies?

ISL 9y ago
A rule of thumb: a hydrogen atom is 0.1 nm in diameter.
- SapphireSun 9y ago
  A caveat to keep in mind, diatomic hydrogen is not 0.2. EDIT: Actually the van der wahl diameter of Hydrogen is about 240pm. 0.12nm is about the radius.
aeleos 9y ago
In the article it says that the cluster is around 0.5 nanometers in diameter.
- logfromblammo 9y ago
  Article said that the inorganic core was 14 atoms. The graphic showed a much larger organic molecule wrapped around the core. It is unclear whether 0.5 nm refers to the inorganic core or the entire molecular complex. It is also possible that the organic molecule changes geometry to open or close the conductive channel, so it could have variable diameter.

castis 9y ago

Im just getting started with hardware electronics so forgive me if this is way off. Also, not to defend the title... Is a standard transistor just two diodes with similar sides facing each other?

deleted 9y ago
[deleted]
Retra 9y ago
I would expect two diodes facing each other would just act like one diode with two connections. A transistor uses one input to control the flow through another path. So something more like a diode that is 'programmable' by another diode.
bdamm 9y ago
In terms of P/N/P layering I believe (from my limited understanding) that what you're saying is generally true. However, given two diodes you can't make a transistor, so it is not equivalent to say that a transistor is just two diodes. Especially at this ultimate scale, proving a diode is not the same as proving a transistor. The mechanism of semi-conductivity is not the same at 0.5nm as it is at 14nm.
logfromblammo 9y ago
A standard field-effect transistor has four connections: gate, base, source, and drain. In MOSFET logic circuits, two of those connections are wired together, depending on whether it is NPN or PNP, and which side of the circuit it is on. Applying voltage between gate and base affects the size of the conductive channel between source and drain, like pinching off the flow from one garden hose by wrapping another hose around it. If you slap two diodes together, you still need to send current through it "sideways" to see a transistor effect.
noobiemcfoob 9y ago
Unless I'm mistaken, that would act as a capacitor. A transistor has a slightly more complicated doping pattern with a gate as shown here: http://cdn4.explainthatstuff.com/fet1.gif http://cdn4.explainthatstuff.com/fet1.gif

brudgers 9y ago

I am not an electrical engineer. My understanding is that in theory two diodes can provide (at least some of) the functionality of a transistor. In practice, using current semiconductor technology, this is impractical/impossible. My reading of the article is the claim that it is possible to provide the behavior of transistors with the single molecule. That is not the same as claiming a single molecule mechanism uses the same technology as current integrated circuits. The analogy I would draw is that transistors have many of the same behaviors as vacuum tubes...or more perhaps more visually the same behaviors as valves in the British usage. Of course I may be completely misunderstanding the article and it's claims, but that is how I resolved the various confusing implications.

hatsunearu 9y ago
>My understanding is that in theory two diodes can provide (at least some of) the functionality of a transistor. very false. bipolar junction transistors have the structure of two diodes back to back but just because you sandwich two diodes doesn't mean it's automatically a transistor. the middle material has to be lightly doped and must be also very thin, or else it won't "trans" much.
- brudgers 9y ago
  Sorry for not being as clear as I would have liked. I am not sure that current semiconductor approaches are relevant to the work of the lab. The analogy may be that the lab is developing a technical approach that is different from current techniques in a manner similar to the way semiconductors were different from vacuum tube techniques.