Materials that conduct electricity/current on an atomic level, are materials that have free electrons that are able to move from atom to atom due to small distances between each atoms outer electron band. In turn, electricity/current is able to flow throughout the material without much effort. Common conductors would be copper, aluminum, gold, and silver with copper being the most commonly used conductor due to low cost for how conductive it is. Gold and silver conductors are usually used in situations where high-speed electrical signals need transported, super high conductivity applications, and resistance to corrosion. Common applications for gold and silver would be for motherboards.
For insulators, they resist the flow of electricity/current due to its’ tight electron bonds to the atom and larger distance between atoms that make it extremely difficult for the electrons to flow from atom to atom. Common insulators are rubber, plastic, dry wood, and glass. Insulators play a key part in electricity by not only keeping us safe from electricity, but also isolating electrical circuits therefore the unique circuits in a system don’t all become one.
Semiconductors fall right in between conductors and insulators. They do not have large or small distances between the outer electron bands usually only allowing electron conductivity with some form of excitation. This excitation is usually dependent on whether the semiconductor is doped or not doped. If the semiconductor is not doped, then the excitation usually occurs with temperature increase which increases conductivity. Doped semiconductors will be altered to carry a more positive or negative charge which would create “holes” that would attract electron. A common doped semiconductor is a P-N diode which only allows electricity to flow in one direction. Most semiconductors are made from silicon.
One of the coolest semiconductor devices in my opinion would have to be central processing units (CPUs). It is insane the amount of "circuits" and logic that are all with in the CPU. This took computers from taking up complete buildings with relay logic and now we walk around with multiple computers every day, like your smart watch, smart phone, and plenty of other devices. Especially, whenever you see the videos where people look at the CPU underneath microscopes and it looks like mini cities that are more complicated to navigate than New York City.
References
Conductors and insulators. Nondestructive Evaluation Physics : Electricity. (n.d.). Retrieved January 25, 2023, from https://www.nde-ed.org/Physics/Electricity/conductorsinsulators.xhtml