Improved Contact Resistance in AIGaN/GaN Heterostructures by Titanium Distribution Control at the Metal-Semiconductor Interface

摘要

A Ti/Au/Al/Ni/Au metallization scheme is demonstrated to achieve a more than tenfold reduction in contact resistance in AIGaN/GaN heterostructure devices. The specific contact resistivity of the contact is 9.1 × 10~(-7) Ω cm~2. The insertion of a gold layer between titanium and aluminum in the proposed structure prevents titanium from diffusing into the aluminum during annealing, allowing titanium to concentrate at the AIGaN interface and thus promoting reaction between titanium and AIGaN/GaN. The new interface is characterized by the penetration of titanium into the nitride layer, providing direct contact with the two-dimensional electron gas.