Thermal stability of defects introduced by electron beam deposition in p-type silicon

The electronic and thermal properties of defects introduced during electron beam deposition (EBD) followed by isochronal annealing of titanium (Ti) contacts on p-Si were investigated. In this work, EBD-deposited Ti Schottky contacts were annealed within a temperature range of 200-400 °C. Current-voltage (I-V) measurements were conducted to monitor the change in electrical characteristics with every annealing step. A barrier height of 0.55 eV was measured on the as-deposited sample. Deep level transient spectroscopy (DLTS) and Laplace-DLTS techniques were employed to identify the defects introduced after EBD and isochronal annealing of the Ti Schottky contacts. DLTS revealed that the main defects introduced during metallization were hole traps H(0.05), H(0.23) and H(0.38). Annealing at 300 °C removed the two hole traps H(0.05) and (0.38). Atomic force microscopy (AFM) was performed on the contacts to monitor their surface topology. The surface of the contacts became rougher as the annealing temperature increased. The slight increase in root-mean-square roughness of the contacts with increasing annealing temperature may be attributed to outdiffusion of Si into Ti layers.