Activation energy of heterojunction diode currents in the limit of interface recombination

Abstract

In this paper, we treat diode currents caused by Shockley–Read–Hall recombination at the interface of pn heterojunctions. We are interested in the activation energy of the saturation current. To this end, we discriminate the cases of ΔEc,v≤0 and ΔEc,v>0, where ΔEc,v is the band offset in the minority carrier band of the small band gap heteropartner, as well as the case of Fermi level pinning. Using analytical considerations, we find that the activation energy of the saturation current equals the band gap of the small band gap heteropartner for ΔEc,v>0 but equals the interface band gap for ΔEc,v≤0. In the case of Fermi level pinning, the value of the potential barrier of the small band gap minority carrier equals the activation energy. These findings serve to discriminate different cases of interface recombination and to give information about the heterojunction energy band diagram.