Iridium–silicide nanowires on Si(110) surface

Abstract

a b s t r a c tWe studied physical and electronic properties of iridium silicide nanowires grown on the Si(110) surface with the help of scanning tunneling microscopy and spectroscopy. The nanowires grow along the [001] direction with an average length of about 100 nm. They have a band gap of~0.5 eV and their electronic properties show similarities with the iridium silicide ring clusters formed on Ir modified Si(111) surface.© 2015 Elsevier B.V. All rights reserved.Ir (Iridium)-silicides have the lowest (highest) Schottky barrier for holes (electrons) which can be used in various device applications on silicon. For example, among silicides, Pt (Platinum)-silicide/p-doped Silicon (Si) diodes are employed in large focal plane arrays for detection in the medium-wavelength infrared light (3-5 μm) [1]. The Schottky barrier height between Pt-silicide and p-doped Si(001) is about 0.23 eV corresponding to a cutoff wavelength of 5.4 μm [2]. In order to extend the cutoff wavelength, it is necessary to choose interfaces with lower Schottky barrier height. The Schottky barrier height between Irsilicide/p-doped silicon is approximately 0.17 eV corresponding to a cutoff wavelength of 7 μm which makes Ir-silicide a promising material for infrared detector applications [3].As continuous miniaturization challenges lithography techniques in electronics, self-assembly based processes become more attractive. One particularly important self-assembled component is metal-silicide nanowires. These nanowires can function as low-resistance interconnects, as fins in FinFET [4] devices and as nano-electrodes for attaching small electronic components within an integrated circuit. It has already been shown that a variety of metals form self-assembled silicide nanowires on the surface of flat and/or vicinal Si substrates [5][6][7][8][9]. Nanowires can be made up of various elements ranging from Bi [10] and rare-earth metals [11-13] to transition metals [14,15]. In comparison to Si(111) and Si(001) surfaces, Si(110) surface has received relatively less attention because the surface reconstruction is complicated and it is difficult to grow single large domains. However, higher hole mobility in devices fabricated on Si(110) surface and the possibility of employing self-assembled nanowires in various applications have recently increased number of studies on these systems [16][17][18]. Unlike 4-fold symmetric Si(001) surface, Si(110) surface is two-fold symmetric which can lead to formation of nanowires along the same direction. Various studies have already reported the existence of metal-silicide nanowires on Si(110) [6,19,20,[21][22][23]. In this letter, we report the formation of Ir-silicide nanowires.The Si(110) samples used in the Scanning Tunneling Microscopy/ Spectroscopy (STM/STS) experiments were cut from nominally flat 76.2 mm by 0.38 mm, single side-polished n-type (phosphorous doped, R = 1.0-10.0 Ohm-cm) wafers. The samples were mounted on molybdenum holders and contact of the samples to any other metal during preparation and experiment...

Structural and electronic properties of Pt induced nanowires on Ge(110)

“…Despite the considerable attention for the 5d transition metal (Au, Pt, and Ir) induced NWs on Ge(001) [3][4][5][6]20], not much attention has been yet paid to the deposition of the these 5d transition metals on Ge(110). During the last decade several reports on the deposition of Dy, Co, Ag, Au, Pt, Gd, Y, Mn, Fe and Ir on the closely related Si(110) surface have appeared [21][22][23][24][25][26][27][28][29][30][31][32]. Visikovskiy and co-authors studied the Pt/Si(110) system and they found four different NW phases for coverages smaller than one monolayer (1 ML) [25], while for more than 1 ML Pt they reported the formation of 3D silicides [26].…”

On the structural and electronic properties of Ir-silicide nanowires on Si(001) surface

“…Ir (iridium) has already been shown to form nanowires on Ge (001), Si (001), and Si (110) surfaces. [20][21][22] In this paper, we report Scanning Tunneling Microscopy/ Spectroscopy (STM/STS) data to reveal electronic properties of Ir-silicide nanowires alongside with ab-initio density functional theory (DFT) calculations to explain the origins of these electronic properties and the structure of Ir-silicide nanowires.…”