Metal/III–V effective barrier height tuning using ALD high-κ dipoles

In summary, we successfully demonstrate R_C and Φ_B,eff tuning of Al/n-GaAs junctions by a MIS diode structure using ALD HfO₂, TiO₂, and ZrO₂ dielectrics. We also introduce for the first time the use of HfO₂/TiO₂, two high-κ dielectrics in combination to further shift the Fermi level and reduce Φ_B,eff. The underlying mechanism is believed to be the formation of a high-κ/high-κ dipole, which opens doors to the exploration of a multitude of other high-κ/high-κ dielectrics to ultimately achieve Φ_B,eff ≤ 0. This MIS structure provides much flexibility in the design of ideal source/drain contacts for III-V MOSFETs and Schottky Barrier FETs, where in real applications highly doped substrates would significantly reduce R_C and Φ_B,eff. Further study of the dipole interaction and effective work function will lead to a better understanding of the physics behind metal/III-V contacts.