Metal/III-V effective barrier height tuning using atomic layer deposition of high-κ/high-κ bilayer interfaces

In this work, we use thin dielectrics to reduce the Al/n-GaAs effective barrier height (ΦB,eff) of metal-insulator-semiconductor (MIS) contacts. We investigate the use of atomic layer deposition of HfO2, Al2O3, TiO2, ZrO2, and bilayer high-κ dielectrics and confirm there is a shift in the Fermi level that reduces the contact resistance. In studying high-κ/high-κ interfaces, we find that despite a thicker dielectric, there is further reduction in ΦB,eff beyond that of a single dielectric, which can be explained by the formation of a high-κ/high-κ dipole. This MIS structure provides great flexibility in the design of source/drain contacts for III-V transistors.