Approximations to Fermi-Dirac integrals and their use in device analysis

A simple,single-expression approximation is derived for the Fermi-Dirac (F-D) Integral F
1/2
(x) in the range -4 ≤ x ≤ +12. This approximation is more accurate (less than 1-percent error throughout) and more useful in device analysis and computer modeling. The approximation procedure is general and can be used to find approximations for F-D Integrals of any order and to any arbitrary degree of accuracy.