Shallow and thermally stable Pt∕W∕Au Ohmic contacts to p-type InGaSb

We report a shallow, thermally stable Pt∕W∕Au (2∕50∕145nm) Ohmic contact to p-InGaSb prepared using a brief (NH4)2S rinse as part of the premetallization surface treatment. Cross-sectional transmission electron microscopy reveals that the Pt∕W∕Au contacts have better thermal stability than previously reported Pd∕W∕Au contacts, with the Pt∕W∕Au contacts remaining shallow even after they are aged at 250°C for 3days. The specific contact resistances of as-deposited Pt∕W∕Au, Pd∕W∕Au, Co∕W∕Au, Cu∕W∕Au, W∕Au, Cr∕W∕Au, and Ag∕W∕Au contacts are also compared, and the (NH4)2S rinse is found to partially relieve Fermi level pinning at the contact∕p-InGaSb interface.