Effects of Sulfur Passivation of GaSb on the Thermal Stability of Al/n-GaSb Contacts

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Abstract
It is demonstrated that sulfur passivation of GaSb before metal evaporation improves thermal stability of Al/n-GaSb Schottky contacts. The contacts were annealed at 300° C, 400° C, and 500° C for 20 s. In the unpassivated contacts annealed at 500° C barrier height decreased by 180 meV, reverse current increased by a factor of 10, breakdown voltage decreased by a factor of 2.6. In the passivated contacts annealed at 500° C, barrier height decreased by 40 meV, reverse current increased by a factor of 3 and breakdown voltage decreased by a factor of 1.4. Formation of thermally stable S–S, S–Sb, and S–Ga bonds and reduction in the interdiffusion and reaction of elements at the interface were used to explain the observations.