Effects of Chemical Treatments and Ultrathin Al 2 O 3 Deposition on InAlN Surface Investigated by X-ray Photoelectron Spectroscopy

The effects of chemical treatments and Al 2 O 3 deposition on the InAlN surface were investigated by X-ray photoelectron spectroscopy (XPS). Independent of the extent of native oxide removal, the In 4d core-level binding energy was the same for untreated, HCl-treated, and HF-treated InAlN. This indicated a strong pinning tendency of the Fermi level at the InAlN bare surface. However, a 300 meV decrease in the In 4d binding energy was observed after atomic layer deposition (ALD) of Al 2 O 3 , which indicated an increase in the negative surface potential at the InAlN surface. The reduction of positive charge at the InAlN surface is discussed.