page_title: Power semiconductor device
section_title: Classifications
hierarchical_section_title: Power semiconductor device / Classifications
context_page_description: A power semiconductor device is a semiconductor device used as a switch or rectifier in power electronics. Such a device is also called a power device or, when used in an integrated circuit, a power IC.
  A power semiconductor device is usually used in "commutation mode", and therefore has a design optimized for such usage; it should usually not be used in linear operation. Linear power circuits are widespread as voltage regulators, audio amplifiers, and radio frequency amplifiers.
  Power semiconductors are found in systems delivering as little as a few tens of milliwatts for a headphone amplifier, up to around a gigawatt in a high voltage direct current transmission line.
context_section_description: A power device may be classified as one of the following main categories (see figure 1):
  A two-terminal device (e.g., a diode), whose state is completely dependent on the external power circuit to which it is connected.
  A three-terminal device (e.g., a triode), whose state is dependent on not only its external power circuit, but also the signal on its driving terminal (this terminal is known as the gate or base).
  A four terminal device (e.g. Silicon Controlled Switch -SCS). SCS is a type of thyristor having four layers and four terminals called anode, anode gate, cathode gate and cathode. the terminals are connected to the first, second, third and fourth layer respectively.
  Another classification is less obvious, but has a strong influence on device performance:
  A majority carrier device (e.g., a Schottky diode, a MOSFET, etc.); this uses only one type of charge carriers.
  A minority carrier device (e.g., a thyristor, a bipolar transistor, an IGBT, etc.); this uses both majority and minority carriers (i.e., electrons and electron holes).
  A majority carrier device is faster, but the charge injection of minority carrier devices allows for better on-state performance.
caption: Fig. 1: The power devices family, showing the principal power switches.
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