Kinetic Engineering of Wurtzite and Zinc-Blende AlSb Shells on InAs Nanowires

• Using AlSb as the model system, we demonstrate that kinetic limitations can lead to the preferential growth of wurtzite (WZ) AlSb shells rather than the thermodynamically stable zinc-blende (ZB) AlSb and that the WZ and ZB relative thickness can be tuned by a careful control of the deposition parameters. We report selective heteroepitaxial radial growth of AlSb deposited by metal-organic vapor phase epitaxy (MOVPE) on InAs nanowire core templates with engineered lengths of axial WZ and ZB segments. AlSb shell thickness, crystal phase, nanostructure, and composition are investigated as a function of the shell growth temperature, Ts, using scanning electron microscopy, transmission electron microscopy, electron tomography, and energy-dispersive X-ray spectroscopy. We find that ZB- and WZ-structured AlSb shells grow heteroepitaxially around the ZB and WZ segments of the InAs core, respectively. Surprisingly, at 390 < Ts < 450 °C, the WZ-AlSb shells are thicker than the ZB-AlSb shells, and their thickness increases with decreasing Ts. In comparison, the ZB-AlSb shell thicknesses increase slightly with increasing Ts. We find that the increased thickness of the WZ-AlSb shells is due to the formation and enhanced deposition on {112-0} facets rather than on the more commonly grown {101-0} sidewall facets. Overall, these results, which are in direct contrast with previous reports suggesting that heteroepitaxial radial growth of III-antimonides is always favored on the ZB-structure facets, indicate that the growth of WZ-AlSb is preferred over the thermodynamically stable ZB-AlSb at lower growth temperatures. We attribute this behavior to kinetic limitations of MOVPE of AlSb on ZB and WZ phases of InAs.

Ämnesord

NATURVETENSKAP  -- Fysik -- Den kondenserade materiens fysik (hsv//swe)

NATURAL SCIENCES  -- Physical Sciences -- Condensed Matter Physics (hsv//eng)

TEKNIK OCH TEKNOLOGIER  -- Nanoteknik -- Nanoteknik (hsv//swe)

ENGINEERING AND TECHNOLOGY  -- Nano-technology -- Nano-technology (hsv//eng)

NATURVETENSKAP  -- Kemi -- Materialkemi (hsv//swe)

NATURAL SCIENCES  -- Chemical Sciences -- Materials Chemistry (hsv//eng)

Nyckelord

AlSb

aluminum antimonide

Core-shell nanowire

selective radial growth

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