Electrical characterization of Ni/Au/AuGe contacts for quantum dot infrared photodetectors

Transfer length method (TLM) structures were fabricated to characterize the Ni/Au/AuGe–n+–GaAs contacts for quantum dot infrared photodetector (QDIP). Low specific contact resistance of the order of 10−5 Ω cm2 indicates formation of a good Ohmic contact. The current–voltage measurements show that current transport is linear with no significant interfacial modification due to alloying of the contact metal. Low contact resistance makes this scheme suitable for the fabrication of heterostructure QDIP devices.

► Ni/Au/AuGe–n+–GaAs contacts were characterized for QDIPs by TLM.
► Specific contact resistance of the order of 10−5 Ω cm2.
► No interfacial resistance change observed as a function of temperature.
► The measured I–V characteristics were linear corresponding to Ohmic contacts.