Single-crystalline Ni₂Ge/Ge/Ni₂Ge nanowire heterostructure transistors

Abstract

In this study, we report on the formation of a single-crystalline Ni(2)Ge/Ge/Ni(2)Ge nanowire heterostructure and its field effect characteristics by controlled reaction between a supercritical fluid-liquid-solid (SFLS) synthesized Ge nanowire and Ni metal contacts. Scanning electron microscopy (SEM) and transmission electron microscopy (TEM) studies reveal a wide temperature range to convert the Ge nanowire to single-crystalline Ni(2)Ge by a thermal diffusion process. The maximum current density of the fully germanide Ni(2)Ge nanowires exceeds 3.5 × 10(7) A cm(-2), and the resistivity is about 88 μΩ cm. The in situ reaction examined by TEM shows atomically sharp interfaces for the Ni(2)Ge/Ge/Ni(2)Ge heterostructure. The interface epitaxial relationships are determined to be [Formula: see text] and [Formula: see text]. Back-gate field effect transistors (FETs) were also fabricated using this low resistivity Ni(2)Ge as source/drain contacts. Electrical measurements show a good p-type FET behavior with an on/off ratio over 10(3) and a one order of magnitude improvement in hole mobility from that of SFLS-synthesized Ge nanowire.

Ge nanowire transistors with high-quality interfaces by atomic-scale thermal annealing

“…2). Scanning electron microscopy (SEM) and transmission electron microscopy (TEM) studies revealed a wide range of annealing temperature, from 400 to 500°C, to drive Ni diffusion into the Ge nanowire and to form single-crystalline Ni2Ge [2]. The formed Ni2Ge has an orthorhombic crystal structure (space group 62) with the set of lattice constants: a = 0.511 run, b = 0.383 nm, and c = 0.726 nm.…”

“…I N the effort of making high-quality nanoscale source/drain contacts to a semiconductor nanowire channel, one attractive strategy is to use thermal annealing to promote the solid-state reaction of metal contacts with semiconductor nanowires [1][2][3][4][5][6]. In the metal-Si(Ge) nanowire system, the produced silicide(germanide) region after annealing can be used as Schottky source/drain contacts for the fabrication of Si(Ge) nanowire transistors.…”

Electrical spin injection and transport in semiconductor nanowires: challenges, progress and perspectives

“…2(b). 22,[44][45][46][47] For example, Fig. For Ge/Si nanowires, however, the 1-D germanidation/silicidation with rapid thermal 90 annealing (RTA) has been extensively studied to produce singlecrystalline germanide/silicide contacts with atomically clean interfaces.…”

“…where P J is the spin polarization of the current injected from 45 the spin injector into the semiconductor channel, is the spin diffusion length, is the semiconductor conductivity, A is the semiconductor channel cross-sectional area, and L is the spatial distance between the spin injector and detector. The ( sign denotes the parallel (anti-parallel) magnetization state for the spin 50 injector and detector.…”

“…SpinFETs are expected 35 to provide unique advantages of low power dissipation and increased functionalities because of their nonvolatility nature and additional control of the current from the ferromagnetic state other than the gate electrode. [9][10][11][12][13][14][15] In the literature, most pioneer work has been 45 conducted on bulk and thin film semiconductors, because they are easy to tune the doping profile and fabricate into devices. For this purpose, the electrical spin injection and transport in a broad range of semiconductors have been extensively studied to find materials with long spin lifetime and diffusion length.…”