Schottky barrier height and electron affinity of titanium on AIN

Approximately 100 or 1000 Angstrom of AlN was deposited on the (0001)Si-fac e of on-axis n-type 6H-SiC. The surfaces were examined by ultraviolet photo emission spectroscopy CUPS) utilizing the He I alpha (21.2 eV and the He II alpha (40.8 eV) excitation. Experimental difficulties are discussed. Titan ium was deposited on the clean surface of in situ grown AlN. The titanium-A lN interface was also characterized with UPS. Two approaches are presented to identify the valence band maximum (VBM) and the electron affinity chi of the clean surface of AlN was found to be either 0 to 1 eV depending upon t he position of the valence band edge. The same assumptions were applied to the analysis of the Ti/AlN interface and, for the case of chi = 0 eV, the p osition of the valence band maximum is 3.4 eV below the position of the Fer mi level. For the case of chi = 1 eV, the position of the valence band maxi mum is 4.4 eV below the position of the Fermi level. Therefore, the p-type Schottky barrier height of titanium on AlN is measured to be 3.4+/-0.2 or 4 .4+/-0.2 eV for chi = 0 eV and chi = 1 eV, respectively. Independent of the selection of the valence band maximum, the observed Schottky barrier diffe red from that predicted by the Schottky-Mott model by 1.5+/-0.2 eV. (C) 200 0 American Vacuum Society. [S0734-211X(00)00104-9].