Johnson's figure of merit explained

Johnson's figure of merit is a measure of suitability of a semiconductor material for high frequency power transistor applications and requirements. More specifically, it is the product of the charge carrier saturation velocity in the material and the electric breakdown field under same conditions, first proposed by Edward O. Johnson of RCA in 1965.[1]

Note that this figure of merit (FoM) is applicable to both field-effect transistors (FETs), and with proper interpretation of the parameters, also to bipolar junction transistors (BJTs).

Example materials

[2]

Material Saturation velocity
x105 m/s
VBreakdown
MV/cm
JFM
Si=1.0
Notes/refs
1.0 0.3 1.0
1.5 0.4 2.7
2.0 3.5 20
0.67 0.5 0.33
2.5 3.3 27.5

JFM figures vary wildly between sources - see external links and talk page.

External links

Si GaAs GaN SiC diamond JFM 1 11 790 410 5800

Notes and References

  1. "Physical limitations on frequency and power parameters of transistors," RCA Review, vol. 26, pp. 163-177, June 1965.
  2. http://web.eecs.umich.edu/~minar/pdf/GaN_review.pdf Gallium Nitride as an Electromechanical Material. R-Z. IEEE 2014