Phase Transformation in Radially Merged Wurtzite GaAs Nanowires.

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Phase Transformation in Radially Merged Wurtzite GaAs Nanowires. / Jacobsson, Daniel; Yang, Fangfang; Hillerich, Karla; Lenrick, Filip; Lehmann, Sebastian; Kriegner, Dominik; Stangl, Julian; Wallenberg, Reine; Dick Thelander, Kimberly; Johansson, Jonas.

In: Crystal Growth & Design, Vol. 15, No. 10, 2015, p. 4795-4803.

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Jacobsson, Daniel ; Yang, Fangfang ; Hillerich, Karla ; Lenrick, Filip ; Lehmann, Sebastian ; Kriegner, Dominik ; Stangl, Julian ; Wallenberg, Reine ; Dick Thelander, Kimberly ; Johansson, Jonas. / Phase Transformation in Radially Merged Wurtzite GaAs Nanowires. In: Crystal Growth & Design. 2015 ; Vol. 15, No. 10. pp. 4795-4803.

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TY - JOUR

T1 - Phase Transformation in Radially Merged Wurtzite GaAs Nanowires.

AU - Jacobsson, Daniel

AU - Yang, Fangfang

AU - Hillerich, Karla

AU - Lenrick, Filip

AU - Lehmann, Sebastian

AU - Kriegner, Dominik

AU - Stangl, Julian

AU - Wallenberg, Reine

AU - Dick Thelander, Kimberly

AU - Johansson, Jonas

PY - 2015

Y1 - 2015

N2 - III-V Nanowires (NWs) grown with metal-organic chemical vapor deposition commonly show a polytypic crystal structure, allowing growth of structures not found in the bulk counterpart. In this paper we studied the radial overgrowth of pure wurtzite (WZ) GaAs nanowires and characterized the samples with high resolution X-ray diffraction (XRD) to reveal the crystal structure of the grown material. In particular, we investigated what happens when adjacent WZ NWs radially merge with each other by analyzing the evolution of XRD peaks for different amounts of radial overgrowth and merging. By preparing cross-sectional lamella samples we also analyzed the local crystal structure of partly merged NWs by transmission electron microscopy. Once individual NWs start to merge, the crystal structure of the merged segments is transformed progressively from initial pure WZ to a mixed WZ/ZB structure. The merging process is then modeled using a simple combinatorial approach, which predicts that merging of two or more WZ NWs will result in a mixed crystal structure containing WZ, ZB, and 4H. The existence large and relaxed segments of 4H structure within the merged NWs was confirmed by XRD, allowing us to accurately determine the lattice parameters of GaAs 4H. We compare the measured WZ and 4H unit cells with an ideal tetrahedron and find that both the polytypes are elongated in the c-axis and compressed in the a-axis compared to the geometrically converted cubic ZB unit cell.

AB - III-V Nanowires (NWs) grown with metal-organic chemical vapor deposition commonly show a polytypic crystal structure, allowing growth of structures not found in the bulk counterpart. In this paper we studied the radial overgrowth of pure wurtzite (WZ) GaAs nanowires and characterized the samples with high resolution X-ray diffraction (XRD) to reveal the crystal structure of the grown material. In particular, we investigated what happens when adjacent WZ NWs radially merge with each other by analyzing the evolution of XRD peaks for different amounts of radial overgrowth and merging. By preparing cross-sectional lamella samples we also analyzed the local crystal structure of partly merged NWs by transmission electron microscopy. Once individual NWs start to merge, the crystal structure of the merged segments is transformed progressively from initial pure WZ to a mixed WZ/ZB structure. The merging process is then modeled using a simple combinatorial approach, which predicts that merging of two or more WZ NWs will result in a mixed crystal structure containing WZ, ZB, and 4H. The existence large and relaxed segments of 4H structure within the merged NWs was confirmed by XRD, allowing us to accurately determine the lattice parameters of GaAs 4H. We compare the measured WZ and 4H unit cells with an ideal tetrahedron and find that both the polytypes are elongated in the c-axis and compressed in the a-axis compared to the geometrically converted cubic ZB unit cell.

U2 - 10.1021/acs.cgd.5b00507

DO - 10.1021/acs.cgd.5b00507

M3 - Article

VL - 15

SP - 4795

EP - 4803

JO - Crystal Growth and Design

T2 - Crystal Growth and Design

JF - Crystal Growth and Design

SN - 1528-7483

IS - 10

ER -