During the 19th century many experiments showed how electrical properties varied with material structures. But not until the 1930’s and 40’s did scientists start to see the rectification and amplification possibilities of semi conductor materials. Now millions of transistors reside on a computer processor and as many as 400 million transistors can be present on a thumbnail size integrated circuit chip.
The usual explanations of how semi conductors work involve moving charge carriers of negative electrons and positive holes. They are an extension of the idea that unlike charges attract whilst like charges repel. My atomic theory has particles as living, proactive energies with roles to play.
Structures desire the most energy efficient, stable state for their particles but they do not act in isolation and are influenced by changes in neighbouring structures. Semi conductor technology is all about particle energy desires and the energy pressures for change they create.
Science has photon energies from sun particles travelling through space to earth and photons from the particles in a blade of grass bringing shape and colour to your eye and linked brain particles. But for some reason it does not see photons of energy as passing across the relatively vast spaces inside of structures between its particles.
I view particles as living energies moving toward a photon source to absorb energy and away from that source when their energy need is satisfied. It is why particles vibrate and why they hold one another at a distance in structures. Particle structures of atoms and molecules will naturally bind to other structures but only if it mutually benefits their energy desires. Otherwise they stay independent.
In structures the more mobile electrons play the role of gathering and distributing environmental photon energies to nucleons. That role has them staying away from other electrons and locating in space volumes called orbitals (they are not orbits). What we term a “hole” results when an electron orbital location becomes vacant. Photon energy flows to nuclear protons encourage energy distributing electrons to occupy that location.
The outer electrons of atoms and molecules are least energy bound to nucleons. Whilst in insulators they are still strongly linked to their parent structure in conductors many are torn between the energy desires of neighbouring atoms or molecules so that photon energy pressures can easily move them. They can be pushed from their location by an approaching electron or encouraged to a “hole” in another structure to supply a photon energy need.
Electron energy gathering (particularly by outer electrons) is what links atomic and molecular structures into larger material structure.
Semiconductor materials like silicon and germanium are themselves energy stable and not good conductors of electricity. However, by doping with other elements we can upset their stability and makes them into highly conductive materials that will allow outer electron movements (current flows) when external voltages are applied.
Voltage is usually provided by a two pole source that delivers a surplus of electrons at one pole and a deficit of electrons at the other pole. The surplus electrons put photon pressures on outer electrons to move. The deficit is in the form of locations (holes) that desire to be occupied by an electron. Each pole will act independently for a minuscule time producing its own local pressures and particle movements. If a circuit exists with low resistance to electron movements continuous current will flow.
A one amp current flow is equivalent to 6.25 billion, billion outer electrons passing through a cross section of a conductor every single second. That might sound a lot but it is a small number relative to the outer electrons in a tiny length of a conductor and most of these electrons progress along a conductor length at less than tortoise pace. What does switch our lights on instantly are the photon energy exchange between those electrons. They act at light speed and consequently any movement of electrons in an electric cable will rapidly set in motion electrons that are even miles away in that same cable. For historical reasons the movement of electrons is seen as a current flow in the opposite direction.
Some structures hold onto their outer electrons strongly, others like silver and copper easily part with their outer electrons. The photon energy pressure needed to displace an outer electron it carries with it. In most circumstances such energy is tiny relative to its inherent or mass energy. That or some of that carried energy is released as photon energy when it engages with another atomic particle structure. The copper cables taking energy to appliances mildly warm; nickel chromium elements in toasters output high numbers of infra-red heat photons; light bulbs output the higher photon energies of visible light.