A longstanding issue in fabrication of semiconductor devices is Fermi level pinning of semiconductor at the metalsemiconductor interface. Selecting metals with different work functions provides only limited control over Ohmic contact or Schottkey contact barrier height. Extensive studies have demonstrated reduced metal-semiconductor contact resistance using thin insulating tunnel barriers with fixed charges. However, the optimal insulating layer thickness (e.g. ～1 nm for Al_2O_3) is difficult to fabricate and thicker insulator layers increase the contact resistance due to reduction in tunneling probability. Dielectric layers below this thickness are generally unreliable due to surface discontinuities. In this study, we control the metal-semiconductor contact barrier through the introduction of sub-2 nm platinum nanoparticles (Pt NPs) deposited by tilted target sputtering (TTS). We show the size-dependent Pt NP properties and their role in Fermi level depinning at the metal-silicon interface with a 0.98 nm Al_2O_3 or 1.6 nm SiO_2 dielectric layer. Our initial study demonstrates that 0.74 nm Pt NPs modified samples show >100-fold higher current density compared to a Ti-thin oxide-Si contact (control). We further show that the contact can be modulated to be either Schottkey or Ohmic using the same contact metal by varying only Pt NP size and areal density.
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