Effect of thermal annealing on Co/n-LEC GaAs (Te) Schottky contacts

The Co/n-GaAs(Te) Schottky barrier diodes have been annealed at temperatures from 100 to 300°C for 5 min and from 350 to 800°C for 1 min in N2 atmosphere. Some expressions have been obtained to interpret the relation between the experiment barrier height Φb,o and equilibrium interface charge density Qss(0) depending on annealing temperature. The Φb,o value has increased and Qss(0) is decreased with increasing annealing temperature up to 550°C. This increase in the barrier height has been attributed to the value of positive Qss(0), which is responsible for the Fermi level pinning. The relation between the Φb,o and Qss(0) depending on annealing temperature is in very good agreement with that of the interface state density distribution especially in the mid-gap.