Injektiovirta

Injektiovirta, or injection current, is a term used in Finnish-language technical literature to describe the electrical current that results when charge carriers are injected into a material, device, or region from a contact or emitter. This kind of current arises when carriers (electrons or holes) cross an interface or are supplied by a source, and it can occur alongside drift and diffusion currents within a device.

Mechanisms of injection include thermionic emission, field-assisted injection, and tunnel injection, which govern how easily carriers move from a contact or emitter into an adjacent layer or region. In semiconductor devices, injection is influenced by energy barriers at interfaces, temperature, and applied bias, and it can occur across pn junctions, metal–semiconductor contacts, or insulating barriers. In vacuum and plasma contexts, injection current describes the flow of charged particles emitted from a cathode or plasma into the surrounding region.

Applications of injection current are broad. It is central to the operation of diodes, light-emitting diodes, laser diodes, and solar cells, where the rate of injection affects brightness, efficiency, and output characteristics. It also plays a role in vacuum tubes, plasma sources, and electrochemical cells, where injected carriers contribute to electrode currents and device performance.

Measurement and control of injection current are typically achieved with a current source, and in research settings, pulsed or time-resolved injection methods help separate injection effects from transport and recombination processes. The term is used across disciplines, and in English literature it is commonly translated as injection current.