- #1
f95toli said:It is a scanning electron microscope (SEM) picture of a what looks like a double quantum dot (two QDs next to each other).
The pale lines (labelled V1, V2 etc) are gate lines used to apply the voltage potential that defines the dots in the centre. The gate lines are metallic and are fabricated on top of a III-V semiconductor (such as GaAs) that has been made in such a way that there is a quasi-2D electron gas (known as a 2DEG) some distance under the surface, by applyting the gate voltage the electrons are confined in the XY plane which in turn creates a dot (or in this case 2.
I like Serena said:What does it do?
GaAs is the second most common semiconducting material (the most common being silicon). It is a very controllable material and can -when combined with various amount of aluminium- be used to make controlled potentiall wells. Most laser diods etc are made from GaAs and so are virtually all high-frequency transistors (e.g. HEMTs used in mobile phones etc).What's the point of using GaAs or whatever?
What's a III-V semiconductor?
How does it generate an electron gas?
What is a quasi-2D electron gas anyway?
Why would the electrons be confined to the XY plane?
How is it that a dot is created because of this?
Quantum dots are tiny semiconductor particles that are only a few nanometers in diameter. They can emit light in a variety of colors and are often used in displays, solar cells, and medical imaging technologies.
Quantum dots exhibit unique optical and electronic properties due to their small size and quantum confinement effects. They can emit light at specific wavelengths, have high photostability, and can be tuned to emit different colors by varying their size.
Quantum dots are typically made through a process called colloidal synthesis, in which precursor materials are heated in a solvent until they form tiny crystals. These crystals can then be coated with a protective shell to prevent them from clumping together.
Quantum dots have a wide range of potential applications, including in displays, solar cells, medical imaging, and quantum computing. They are also being researched for use in targeted drug delivery and environmental sensing.
While quantum dots have shown great promise in various applications, there are concerns about their potential toxicity. Research is ongoing to better understand their effects on human health and the environment, and steps are being taken to ensure their safe use in consumer products.