Demonstration of Hexagonal Phase Silicon Carbide Nanowire Arrays with Vertical Alignment

Abstract

SiC nanowire based electronics hold promise for data collection in harsh environments wherein conventional semiconductor platforms would fail. However, the full adaptation of SiC nanowires as a material platform necessitates strict control of nanowire crystal structure and orientation for reliable performance. Toward such efforts, we report the growth of hexagonal phase SiC nanowire arrays grown with vertical alignment on commercially available single crystalline SiC substrates. The nanowire hexagonality, confirmed with Raman spectroscopy and atomic resolution microscopy, displays a polytypic distribution of predominantly 2H and 4H. Employing a theoretical growth model, the polytypic distribution of hexagonal phase nanowires is accurately predicted in the regime of high supersaturation. Additionally, the reduction of disorder-induced phonon density of states is achieved while maintaining nanowire morphology through a postgrowth anneal. The results of this work expand the repertoire of SiC nanowires by implementing a low-temperature method that promotes polytypes outside the well-studied cubic phase and introduces uniform, vertical alignment on industry standard SiC substrates.

Cobalt Oxide-Decorated Silicon Carbide Nano-Tree Array Electrode for Micro-Supercapacitor Application

“…The as-prepared SiC NW film and Co 3 O 4 /SiC NTA film were further characterized by Raman spectroscopy ( Figure 2 ). As shown in Figure 2 a, the SiC NW film shows a hexagonal crystal structure composed of polytypes of SiC, and is predominantly 4H-like [ 23 ]. In Figure 2 b, three sharp peaks at 658, 460, and 185 cm −1 were detected in the Raman spectrum of Co 3 O 4 /SiC NTA film; those peaks correspond to 1 A 1g , 1 E g and 3 F 2g Raman active modes of Co 3 O 4 [ 12 , 25 , 26 ].…”

“…The n-type 4H-SiC(0001) (Cree Research, Silicon Drive, NC, USA) wafer was used as the substrate for growing the SiC NWs on it. The 4H-SiC(0001) wafer were carefully cleaned before use, and the SiC NW arrays were prepared on the abovementioned substrate according to our previous reports, i.e., the Ni-catalyzed CVD method [ 12 , 22 , 23 ]. In brief, a ~2.5 nm Ni film was fabricated onto a cleaned 4H-SiC(0001) wafer substrate by using the electron beam evaporation; the as-prepared substrate was then transported into a hot-wall chemical vapor deposition (CVD) tube furnace to a base pressure of 30 × 10 −3 Torr, wherein it was further heated to 950 °C at a rate of 50 °C min −1 at ~5 Torr under 10 sccm flow of H 2 (Praxair, 99.99%, Danbury, CT, USA).…”

3C-SiC Nanowires In-Situ Modified Carbon/Carbon Composites and Their Effect on Mechanical and Thermal Properties

“…The specific elemental composition of the as-prepared sample, taken from Spot 1 (in red) in Figure 2 c was further investigated using EDS, as displayed in the inset in Figure 2 f. Due to the influence of the carbon matrix, the atomic ratio of Si and C was about 1:3. The Raman spectra ( Figure 2 g) show a peak at around 791 cm −1 and a broad peak in Spot 1 (in red), which were attributed to the 3C-SiC nanowires [ 21 ].…”

Strong Zero-Phonon Transition from Point Defect-Stacking Fault Complexes in Silicon Carbide Nanowires

“…We attribute the former group to single-crystalline nanowires and the latter group to nanowires with polytype mixing. 32,33 To investigate the crystal structures of the nanowires, we performed transmission electron microscopy (TEM) studies. The CVD-grown nanowires generally grew along the ⟨111⟩ direction with a cubic phase.…”

“…Also, the nanowires have a variety of shapes, and we can divide them into two distinct groups: straight nanowires with a smooth surface (Figure a) and irregularly shaped nanowires with a rough surface (Figure b). We attribute the former group to single-crystalline nanowires and the latter group to nanowires with polytype mixing. , …”