Comment on “Influence of crystal polarity on the properties of Pt/GaN Schottky diodes” [Appl. Phys. Lett. 77, 2012 (2000)]

n, GaN Because of its uniaxial wurtzite structure GaN exhib new interesting electronic properties as compared with c sical, cubic III–V semiconductors. Many of these propert are due to the built-in strong polarization fields, spontaneo and in addition, piezoelectric ones in the case of strai layers. In this context, Karrer et al. report about differing Schottky-barrier heights of Pt/GaN contacts measured molecular-beam epitaxy grown-GaN layers with Gaand N-face polarity. From capacitance–voltage and curre voltage measurements, the authors derive barrier hei Fexp(Ga2face)51.1 eV and Fexp(N2face)50.9 eV for GaN~0001! and GaN(0001 ̄), respectively. The interpretatio of the authors for this obvious difference is in terms of different band bending on the two polar faces, inferred fr a different screening behavior of the internal polarizat charges at the surfaces. This different band bending claimed to lead to different electron affinities at the two s faces and therefore different Schottky-barrier heights. 1