Two-Dimensional Materials Inserted at the Metal/Semiconductor Interface: Attractive Candidates for Semiconductor Device Contacts

• Published in: Nano letters Vol. 18; no. 8; pp. 4878 - 4884
• Main Authors: Lee, Min-Hyun, Cho, Yeonchoo, Byun, Kyung-Eun, Shin, Keun Wook, Nam, Seong-Geol, Kim, Changhyun, Kim, Haeryong, Han, Sang-A, Kim, Sang-Woo, Shin, Hyeon-Jin, Park, Seongjun
• Format: Journal Article
• Language: English
• Published: United States American Chemical Society 08.08.2018
• Subjects: specific contact resistivity; work function modulation; 2D material-inserted contact; pinning effect; graphene; hexagonal boron nitride
• ISSN: 1530-6984; 1530-6992
• DOI: 10.1021/acs.nanolett.8b01509

Metal–semiconductor junctions are indispensable in semiconductor devices, but they have recently become a major limiting factor precluding device performance improvement. Here, we report the modification of a metal/n-type Si Schottky contact barrier by the introduction of two-dimensional (2D) materials of either graphene or hexagonal boron nitride (h-BN) at the interface. We realized the lowest specific contact resistivities (ρc) of 3.30 nΩ cm2 (lightly doped n-type Si, ∼ 1015/cm3) and 1.47 nΩ cm2 (heavily doped n-type Si, ∼ 1021/cm3) via 2D material insertion are approaching the theoretical limit of 1.3 nΩ cm2. We demonstrated the role of the 2D materials at the interface in achieving a low ρc value by the following mechanisms: (a) 2D materials effectively form dipoles at the metal–2D material (M/2D) interface, thereby reducing the metal work function and changing the pinning point, and (b) the fully metalized M/2D system shifts the pinning point toward the Si conduction band, thus decreasing the Schottky barrier. As a result, the fully metalized M/2D system using atomically thin and well-defined 2D materials shows a significantly reduced ρc. The proposed 2D material insertion technique can be used to obtain extremely low contact resistivities in metal/n-type Si systems and will help to achieve major performance improvements in semiconductor technologies.