Surface cleaning and annealing effects on Ni/AlGaN interface atomic composition and Schottky barrier height

Internal photoemission spectroscopy reveals changes in the Schottky barrier height of Ni on AlGaN/GaN high electron mobility transistor structures with premetallization processing conditions and postmetallization ultrahigh-vacuum annealing. These variations in the internal photoemission Schottky barrier height are correlated with AlGaN near-band-edge emissions from low-energy electron-excited nanoluminescence spectroscopy and Ni/AlGaN interface impurities by secondary ion mass spectrometry. We show that changes in the Schottky barrier height and the appearance of dual barriers are dominated by changes in the local Al mole fraction. Interfacial oxygen and carbon have secondary but systematic effects as well. (C) 2004 American Institute of Physics.