Fundamentals of Silicon Carbide Technology: Growth, Characterization, Devices and Applications

Chapter 10Optimization and Comparison of Power Devices

10.1 Blocking Voltage and Edge Terminations for SiC Power Devices

An essential requirement of all semiconductor power devices is the ability to withstand a large terminal voltage with minimal leakage current in the off state. The maximum terminal voltage a device can withstand is called the blocking voltage. The blocking voltage is generally determined by material properties as well as device design. The limiting mechanism may be any of the following: (i) punch-through of the base region in a MOSFET (metal-oxide-semiconductor field effect transistor), BJT (bipolar junction transistor), IGBT (insulated-gate bipolar transistor), or thyristor; (ii) avalanche breakdown in a reverse-biased pn or Schottky junction, either as a discrete rectifier or as a part of a switching transistor or thyristor; (iii) excessive leakage current in a reverse-biased pn or Schottky junction; or (iv) excessive electric field in the oxide of an MOS-based power device such as a MOSFET or IGBT.

Punch-through can be avoided by making the doping-thickness product of the base region large enough that the base cannot be completely depleted before the onset of avalanche breakdown. This requires

10.1

where and represent the doping and width of the base region ...