title: The Effect of Interfacial Dipoles on the Metal-Double Interlayers-Semiconductor Structure and Their Application in Contact Resistivity Reduction.
abstract: We demonstrate the contact resistance reduction for III-V semiconductor-based electrical and optical devices using the interfacial dipole effect of ultrathin double interlayers in a metal-interlayers-semiconductor (M-I-S) structure. An M-I-S structure blocks metal-induced gap states (MIGS) to a sufficient degree to alleviate Fermi level pinning caused by MIGS, resulting in contact resistance reduction. In addition, the ZnO/TiO2interlayers of an M-I-S structure induce an interfacial dipole effect that produces Schottky barrier height (ΦB) reduction, which reduces the specific contact resistivity (ρc) of the metal/n-type III-V semiconductor contact. As a result, the Ti/ZnO(0.5 nm)/TiO2(0.5 nm)/n-GaAs metal-double interlayers-semiconductor (M-DI-S) structure achieved a ρcof 2.51 × 10-5Ω·cm2, which exhibited an ∼42 000× reduction and an ∼40× reduction compared to the Ti/n-GaAs metal-semiconductor (M-S) contact and the Ti/TiO2(0.5 nm)/n-GaAs M-I-S structure, respectively. The interfacial dipole at the ZnO/TiO2interface was determined to be approximately -0.104 eV, which induced a decrease in the effective work function of Ti and, therefore, reduced ΦB. X-ray photoelectron spectroscopy analysis of the M-DI-S structure also confirmed the existence of the interfacial dipole. On the basis of these results, the M-DI-S structure offers a promising nonalloyed Ohmic contact scheme for the development of III-V semiconductor-based applications.
authors.affiliation: Department of Nano Semiconductor Engineering, Korea University , Seoul 136-701, Korea.
authors.forename: Sun-Woo
authors.identifier: http://orcid.org/0000-0002-2041-1451
authors.initials: SW
authors.lastname: Kim
authors.affiliation: School of Electrical Engineering, Korea University , Seoul 136-701, Korea.
authors.forename: Seung-Hwan
authors.identifier: http://orcid.org/0000-0002-5899-2853
authors.initials: SH
authors.lastname: Kim
authors.affiliation: School of Electrical Engineering, Korea University , Seoul 136-701, Korea.
authors.forename: Gwang-Sik
authors.identifier: http://orcid.org/0000-0002-9329-4006
authors.initials: GS
authors.lastname: Kim
authors.affiliation: Division of Materials Science and Engineering, Hanyang University , Seoul 133-791, Korea.
authors.forename: Changhwan
authors.initials: C
authors.lastname: Choi
authors.affiliation: Material Science and Engineering, Inha University , Incheon 402-751, Korea.
authors.forename: Rino
authors.initials: R
authors.lastname: Choi
authors.affiliation: Department of Nano Semiconductor Engineering, Korea University , Seoul 136-701, Korea.|School of Electrical Engineering, Korea University , Seoul 136-701, Korea.
authors.forename: Hyun-Yong
authors.identifier: http://orcid.org/0000-0001-9446-5981
authors.initials: HY
authors.lastname: Yu
keywords: Fermi level pinning; Schottky barrier; gallium arsenide; interfacial dipole; specific contact resistivity