  Majorana zero modes (MZMs), prime candidates for topological quantum bits,
are detected as zero bias conductance peaks (ZBPs) in tunneling spectroscopy
measurements. Implementation of a narrow and high tunnel barrier in the next
generation of Majorana devices can help to achieve the theoretically predicted
quantized height of the ZBP. We propose a material-oriented approach to
engineer a sharp and narrow tunnel barrier by synthesizing a thin axial segment
of GaxIn1-xSb within an InSb nanowire. By varying the precursor molar fraction
and the growth time, we accurately control the composition and the length of
the barriers. The height and the width of the GaxIn1-xSb tunnel barrier are
extracted from the Wentzel-Kramers-Brillouin (WKB)-fits to the experimental I-V
traces.
