What is the forward voltage (VF) of Schottky barrier diodes (SBDs)?

Depending on the metal used, SBDs have a rated forward voltage (VF) between 0.4 V to 0.7 V, which is lower than the forward voltage of pn junction diodes. However, the withstand voltage of silicon SBDs is 20 to 150 V, not higher than that of pn junction diodes.

Toshiba also provides SBDs fabricated with a wide-bandgap semiconductor (SiC) having a high electric breakdown field that withstand up to 650 V.
Fig. 1 compares the band diagrams of pn junction diodes and SBDs in the non-biased state. The forward voltage (VF) of pn junction diodes is determined by a difference in potential energy between p-type and n-type semiconductors whereas the forward voltage (VF) of SBDs is determined by a difference between the work function of a metal and the electron affinity of an n-type semiconductor such as silicon (i.e., Schottky barrier). Therefore, SBDs with low VF can be created by using a metal that has a work function close to the electron affinity of the n-type semiconductor (e.g., silicon). Fig. 2 shows the difference in VF, depending on the metal used.

Fig. 1 Band diagrams of pn junction diodes and SBDs (in the non-biased state)
Fig. 1 Band diagrams of pn junction diodes and SBDs (in the non-biased state)
Fig. 2 I-V characteristics (characteristics of different metals)
Fig. 2 I-V characteristics (characteristics of different metals)

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