Electrical characterization of interface stability between magnesium and selenium-passivated n-type silicon (001)

We reported selenium passivation of silicon (001) surface and showed the ohmic nature of the interface between magnesium and selenium-passivated n -type silicon (001). In this paper, we present a detailed study on the thermal stability of this interface. Magnesium contacts on selenium-passivated silicon (001) are annealed from 200°C to 500°C at an interval of 50°C and then characterized by current-voltage measurements. Schottky barrier heights of the contacts are measured by capacitance-voltage and activation-energy methods. Schottky behaviour sets in only when the interface is subjected to annealing above 375°C. On the contrary, magnesium contacts on bare silicon (001) turn from ohmic to Schottky at much lower temperatures. The temperature difference is 50-150°C. We deduce that selenium passivation suppresses silicidation between magnesium and silicon, because it reduces the surface reactivity of silicon by eliminating dangling bonds and relaxing strained bonds.