Metallic Nanoalloys on Vertical GaAs Nanowires: Growth Mechanisms and Shape Control of Ni-GaAs Compounds

Abstract

GaAs nanowires are promising candidates for emerging devices in a broad field of applications (e.g., nanoelectronics, photodetection, or photoconversion). These nanostructures benefit greatly from a vertical integration, as it allows for the exhibition of the entire nanowire surface. However, one of the main challenges related to vertical integration is the conception of an efficient method to create low resistive contacts at nanoscale without degrading the device performance. In this article, we propose a complementary metal-oxide-semiconductor (CMOS)-compatible approach to form alloyed contacts at the extremities of vertical GaAs nanowires. Ni-based and Pd-based alloys on different vertical GaAs nanostructures have been characterized by structural and chemical analyses to identify the phase and to study the growth mechanisms involved at the nanoscale. It is shown that the formation of the Ni 3 GaAs alloy on top of nanowires following the epitaxial relation Ni 3 GaAs(0001)∥GaAs( 111) leads to a pyramidal shape with four faces. Finally, guidelines are presented to tune the shape of this alloy by varying the initial metal thickness and nanowire diameters. It will facilitate the fabrication of a nanoalloy structure with tailored shape characteristics to precisely align with a designated application.

Logic Gates Based on 3D Vertical Junctionless Gate-All-Around Transistors with Reliable Multilevel Contact Engineering

“…The remaining undesired metal layer can be stripped without leaving any traces or defects. Even if the presented demonstration is performed on a silicon nanowire channel, the process route can be directly applicable to other semiconducting materials as such high-mobility SiGe nanowires and III–V materials, like GaAs and GaSb. , …”