The contact mechanism and design principles for alloyed Ohmic contacts to n-GaN were investigated in Mohammad’s paper [ J. Appl. Phys. 95, 7940 (2004) ]. Mohammad’s study demonstrated that both tunneling and thermionic emission were equally important for low resistivity at the metals/n-GaN interfaces. As regards this Comment, we point out the fundamental errors of this interpretation. In addition, we find that the results shown in Figs. 3–6 of Mohammad’s paper are incorrect because the lower effective barrier height (BH) of less than 0 eV (due to the induced BH reduction by image force lowering or band gap narrowing) and a variable (c1) were neglected by the author.