As the saying goes, learning proceeds from the identified to the unknown. Our definition of anode/cathode, as given in section~1, is straightforward and useful.
Current flows from the cathode to the positively charged anode; however, the electrons truly circulate from the anode to the cathode. Derived from Greek, cathode and anode imply “down” and “up” respectively. In a semiconductor diode, the anode is the P-doped layer which initially provides holes to the junction. In the junction region, the holes provided by the anode mix with electrons equipped from the N-doped region, making a depleted zone. As the P-doped layer supplies holes to the depleted area, adverse dopant ions are left behind in the P-doped layer (‘P’ for optimistic cost-provider ions).
Modern vacuum tubes use thermionic emission, by which the cathode is manufactured from a skinny wire filament that’s heated by a separate electrical current passing through it. The increased random … Read More