Pt/Au Schottky Contacts to Modulation-Doped Al_xGa_1-xN/GaN Heterosturctures Using Pre-deposition Surface Treatment

Pt/Au Schottky contacts were fabricated on modulation-doped Al_0.22GaN_0.78/GaN heterostructures. Some different pre-deposition surface treatments were used to prevent the formation of the native oxide layer on the Al_0.22GaN_0.78 surface. X-ray photoelectron spectroscopy (XPS) measurements indicate that the pre-deposition surface treatment with boiling (NH₄)₂S solution can remove the native oxide layer on the Al_0.22GaN_0.78 surface effectively. The highest Schottky barrier height of 1.13 eV was obtained on the (NH₄)₂S-treated Al_0.22GaN_0.78 heterostructure.