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

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 Delta E(c,v)<= 0 and Delta E(c,v)>0, where Delta E(c,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 Delta E(c,v)>0 but equals the interface band gap for Delta E(c,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.