Nanospectroscopic Imaging of Twinning Superlattices in an Individual GaAs-AlGaAs Core–Shell Nanowire

Abstract

GaAs nanowires (NWs) exhibit different, zinc blende (ZB) and wurzite (WZ), crystalline phases and one generally finds an uncontrolled switching between both phases on a scale of 1–10 nm. The change of crystalline structure and stacking fault density strongly affects the local confinement potential of GaAs NWs. Combining low temperature near-field spectroscopic imaging and transmission electron microscopy measurements performed on the very same individual GaAs nanowire allows us to gain an understanding of the local structure–property correlations in such wires. From the photoluminescence measurements at subwavelength spatial resolution local characteristics of the band structure are derived. In particular, our method enables us to assign the observed band gap reduction to the high level of impurity dopants and to distinguish emission from ZB-type regions and from periodically twinned superlattice regions. In this way we demonstrate the ability to trace spatial variations of the crystal structure along the wire axis by all-optical means. Our results provide direct and quantitative insight into the correlations between morphology and optics of GaAs nanowires and hence present an important step toward band gap engineering of nanowires by controlled crystal phase formation.

Electronic properties of wurtzite GaAs: A correlated structural, optical, and theoretical analysis of the same polytypic GaAs nanowire

“…Nano Res. 2018, 11(9): 4708-4721 two rotationally twinned segments can be seen as a 2 ML thick insertion of the WZ material in a ZB matrix [41][42][43]. The transition at 1.477 eV is also detected in domain B (Fig.…”

Brief Review of Epitaxy and Emission Properties of GaSb and Related Semiconductors

“…GaAsSb NWs fabricated by MBE can be divided into two types: those grown on Si(111) substrates and those grown on GaAs nanowire stems. The GaAsSb NWs have been realized with Sb components in the 0-0.44 range [85][86][87]. This makes the band gap of GaAsSb NWs easier to be tuned.…”

Направленное излучение нитевидных нанокристаллов GaAs/AlGaAs, легированных бериллием

“…При их создании ННК легируют примесями p-или n-типа (например, Be или Si соответственно). Как было показано, оптические свойства ННК зависят от концентрации легирующей примеси [10]. Однако вопрос о влиянии примесей на направленность излучения в ННК на данный момент практически не исследован.…”