TY - JOUR
T1 - Kinetic control of morphology and composition in Ge/GeSn core/shell nanowires
AU - Assali, Simone
AU - Bergamaschini, Roberto
AU - Scalise, Emilio
AU - Verheijen, Marcel A.
AU - Albani, Marco
AU - Dijkstra, Alain
AU - Li, Ang
AU - Koelling, Sebastian
AU - Bakkers, Erik P.A.M.
AU - Montalenti, Francesco
AU - Miglio, Leo
PY - 2020/2/25
Y1 - 2020/2/25
N2 - The growth of Sn-rich group-IV semiconductors at the nanoscale can enrich the understanding of the fundamental properties of metastable GeSn alloys. Here, we demonstrate the effect of the growth conditions on the morphology and composition of Ge/GeSn core/shell nanowires by correlating the experimental observations with a theoretical interpretation based on a multiscale approach. We show that the cross-sectional morphology of Ge/GeSn core/shell nanowires changes from hexagonal to dodecagonal upon increasing the supply of the Sn precursor. This transformation strongly influences the Sn distribution as a higher Sn content is measured under the {112} growth front. Ab initio DFT calculations provide an atomic-scale explanation by showing that Sn incorporation is favored at the {112} surfaces, where the Ge bonds are tensile-strained. A phase-field continuum model was developed to reproduce the morphological transformation and the Sn distribution within the wire, shedding light on the complex growth mechanism and unveiling the relation between segregation and faceting. The tunability of the photoluminescence emission with the change in composition and morphology of the GeSn shell highlights the potential of the core/shell nanowire system for optoelectronic devices operating at mid-infrared wavelengths.
AB - The growth of Sn-rich group-IV semiconductors at the nanoscale can enrich the understanding of the fundamental properties of metastable GeSn alloys. Here, we demonstrate the effect of the growth conditions on the morphology and composition of Ge/GeSn core/shell nanowires by correlating the experimental observations with a theoretical interpretation based on a multiscale approach. We show that the cross-sectional morphology of Ge/GeSn core/shell nanowires changes from hexagonal to dodecagonal upon increasing the supply of the Sn precursor. This transformation strongly influences the Sn distribution as a higher Sn content is measured under the {112} growth front. Ab initio DFT calculations provide an atomic-scale explanation by showing that Sn incorporation is favored at the {112} surfaces, where the Ge bonds are tensile-strained. A phase-field continuum model was developed to reproduce the morphological transformation and the Sn distribution within the wire, shedding light on the complex growth mechanism and unveiling the relation between segregation and faceting. The tunability of the photoluminescence emission with the change in composition and morphology of the GeSn shell highlights the potential of the core/shell nanowire system for optoelectronic devices operating at mid-infrared wavelengths.
KW - first-principles calculations
KW - germanium tin
KW - heterostructure
KW - kinetic growth model
KW - photoluminescence
KW - segregation
KW - semiconductor nanowire
UR - http://www.scopus.com/inward/record.url?scp=85081175472&partnerID=8YFLogxK
U2 - 10.1021/acsnano.9b09929
DO - 10.1021/acsnano.9b09929
M3 - Article
C2 - 31972083
AN - SCOPUS:85081175472
SN - 1936-0851
VL - 14
SP - 2445
EP - 2455
JO - ACS Nano
JF - ACS Nano
IS - 2
ER -