Saturation of fermi energy in highly Sn doped InGaAs

摘要

We describe a method of Fermi energy measurement based on the analysis of thermionic emission and diffusion over a barrier with a build-in charge. The method was successfully tested by measuring the Fermi energy in GaAs. In addition, this method was applied to measure the Fermi energy in heavily Sn doped InGaAs. The dependence of the Fermi energy determined by thermionic emission on carrier concentration measured by Hall effect strongly deviates from standard theoretical predictions. The most striking observed anomaly is the near saturation of the Fermi level at a value E_f approx= 130 meV when the mobile carrier concentration exceeds 10~(19) cm~(-3). Our results call for a thorough re-examination of the existing theory.