Comment on I. Lashkevych, O. Yu. Titov, and Yu. G. Gurevich, “Ohm’s Law for a Bipolar Semiconductor: The Role of Carrier Concentration and Energy Nonequilibria” [J. Electron. Mater., 46, 585 (2017)]

In a recent publication [J. Electron. Mater., 46, 585 (2017)], a number of formulae are presented for the effective conductivity of a bipolar semiconductor sandwiched between two metal contacts. However, the results are shown to be nonphysical, and the explanation is traced to errors appearing in previous literature on the subject.