Data presented in figures in the article titled: Unveiling the Growth Mode Switching Role of As in the Formation of Dodecagonal/Hexagonal GaN Microrods, citation: Cryst. Growth Des. 2024, 24, 18, 7424–7431, https://doi.org/10.1021/acs.cgd.4c00418
Figure 1. SEM images of GaN microrods in various stages of growth. An isolated column grown for 5 h is shown in panel (a) with all its features clearly visible. Initial stages of growth are shown in panels (b–e) with columns grown for (b) 0 min, only GaN buffer; (c) 5; (d) 15; and (e) 30 min. Imaged areas are 10 × 10 μm2. Panel (f) shows an ensemble od columns grown for 5 h.
Figure 2. (a) EDS spectra of the microrods top with and without additional particles. The inset shows the areas probed using a beam convergence semiangle of 21.4 mrad, HAADF detector collection angles of 79.5–200 mrad, and probe beam current of 80 pA. In panel (b) As containing shells preserved by shorter HCl etching are presented.
Figure 3. Density of formed microrods shown as a function of time. Dashed lines are guides to the eye indicating the initial increase in the density and subsequent saturation. The final point shows the density measured for a sample grown for 5 h but under different growth conditions.
Figure 4. (a) Detailed 1 × 1 μm2 SEM image of the initial phase of growth of a GaN microrod. A magnified part indicated by the 500 × 500 nm2 white square is shown in panel (b). Selected growth plane edges are highlighted by green lines. (c) 1 × 1 μm2 AFM image of a similar microrod. A magnified part indicated by the 500 × 500 nm2 white square is shown in panel (d). Hexagonal symmetry is highlighted by green lines. Time of growth was 2.5 min for both columns.
Figure 5. SEM images of GaN microrods grown under Ga-excessive conditions: (a) an ensemble of four columns grown under a shared Ga droplet, the central column exhibits a hexagonal symmetry while the other three are mixed hexagonal/dodecagonal; (b) a top view of two columns that shared a Ga droplet. SEM images of microrods grown for 3 h with arsenic flux stopped (c) after 2.5 h (30 min of growth without As), picture of as-grown sample, (d) after 2.5 h (30 min of growth without As), picture of an individual microrod after HCl cleaning, (e) after 2 h (as-grown, 1 h of growth without As), (f) after 1.5 h (as-grown, 1.5 h of growth without As).
Figure 6. STEM characterization of the cross section of the hexagonal plane capped GaN microrods. A SEM image in (a) shows the top part of a microrod, and the rectangle marker indicates the region from which a FIB TEM lamella was prepared for cross-sectional analysis. An HAADF-STEM image in (b) shows both the dodecagonal and hexagonal facets, with solid line markers for guidance. A schematic representation of the microrod cross-section is shown in (c), with labeled facet planes. In (d,g), HAADF-STEM images show edges of the hexagonal side and of the dodecagonal side in-between the hexagonal side edges, respectively, parallel to the top of the image frame. High-resolution images in (e,h) from marked regions in (d,g) reveal that m-planes and a-planes of GaN are parallel to these edges, respectively. Corresponding FFT images are shown in (f,i). Images (e,h) are processed using ROF denoise filter and false color coded using LUT processing in imageJ software. The scale bar in (a,b,d,g) is 200 nm, in (e,h) is 1 nm. Raw images are available in Supporting Information Figure S1.
SEM images aquired on a Thermo Fisher Scientific HELIOS Nanolab 450 HP system.
EDS data collected with ThermoFisher EDS software and processed in OriginPro.
TEM/STEM images aquired on a FEI TITAN Cubed 60-300 system.
FFT images processed using ROF denoise filter and false color coded using LUT processing in imageJ software.
(2024-09-06)
