1 research outputs found
Direct Electrical Probing of Periodic Modulation of Zinc-Dopant Distributions in Planar Gallium Arsenide Nanowires
Selective
lateral epitaxial (SLE) semiconductor nanowires (NWs),
with their perfect in-plane epitaxial alignment, ability to form lateral
complex p–n junctions <i>in situ</i>, and compatibility with planar processing, are a
distinctive platform for next-generation device development. However,
the incorporation and distribution of impurity dopants in these planar
NWs <i>via</i> the vapor−liquid−solid growth mechanism remain relatively unexplored. Here, we present
a detailed study of SLE planar GaAs NWs containing multiple alternating
axial segments doped with Si and Zn impurities by metalorganic chemical
vapor deposition. The dopant profile of the lateral multi-p–n
junction GaAs NWs was imaged simultaneously with nanowire topography
using scanning microwave impedance microscopy and correlated with
infrared scattering-type near-field optical microscopy. Our results
provide unambiguous evidence that Zn dopants in the periodically twinned
and topologically corrugated p-type segments are preferentially segregated
at twin plane boundaries, while Si impurity atoms are uniformly distributed
within the n-type segments of the NWs. These results are further supported
by microwave impedance modulation microscopy. The density functional
theory based modeling shows that the presence of Zn dopant atoms reduces
the formation energy of these twin planes, and the effect becomes
significantly stronger with a slight increase of Zn concentration.
This implies that the twin formation is expected to appear when a
threshold planar concentration of Zn is achieved, making the onset
and twin periodicity dependent on both Zn concentration and nanowire
diameter, in perfect agreement with our experimental observations