Non-equilibrium induction of tin in germanium: towards direct bandgap Ge(1-x)Sn(x) nanowires.
The development of non-equilibrium group IV nanoscale alloys is critical to achieving new functionalities, such as the formation of a direct bandgap in a conventional indirect bandgap elemental semiconductor. Here, we describe the fabrication of uniform diameter, direct bandgap Ge(1-x)Sn(x) alloy nanowires, with a Sn incorporation up to 9.2 at.%, far in excess of the equilibrium solubility of Sn in bulk Ge, through a conventional catalytic bottom-up growth paradigm using noble metal and metal alloy catalysts. Metal alloy catalysts permitted a greater inclusion of Sn in Ge nanowires compared with conventional Au catalysts, when used during vapour-liquid-solid growth. The addition of an annealing step close to the Ge-Sn eutectic temperature (230 °C) during cool-down, further facilitated the excessive dissolution of Sn in the nanowires. Sn was distributed throughout the Ge nanowire lattice with no metallic Sn segregation or precipitation at the surface or within the bulk of the nanowires. The non-equilibrium incorporation of Sn into the Ge nanowires can be understood in terms of a kinetic trapping model for impurity incorporation at the triple-phase boundary during growth.
Materials Chemistry &Analysis Group, Department of Chemistry, Tyndall National Institute, University College Cork, Cork T12 YF78, Ireland.
Subhajit
S
Biswas
Materials Chemistry &Analysis Group, Department of Chemistry, Tyndall National Institute, University College Cork, Cork T12 YF78, Ireland.
Jessica
J
Doherty
Department of Photonics, Tyndall National Institute, University College Cork, Cork T12 R5CP, Ireland.|CAPPA, Cork Institute of Technology, Cork T12 T66T, Ireland.
Dzianis
D
Saladukha
SuperSTEM Laboratory, SciTech Daresbury Campus, Daresbury WA4 4AD, UK.
Quentin
Q
Ramasse
Department of Physics, Bose Institute, Kolkata 700009, India.
Dipanwita
D
Majumdar
Group for Simulation and Theory of Atomic-Scale Material Phenomena (stAMP), Department of Mechanical and Industrial Engineering and Department of Bioengineering, Northeastern University, Boston, Massachusetts 02115, USA.
Moneesh
M
Upmanyu
Department of Physics, Bose Institute, Kolkata 700009, India.
Achintya
A
Singha
Department of Photonics, Tyndall National Institute, University College Cork, Cork T12 R5CP, Ireland.|CAPPA, Cork Institute of Technology, Cork T12 T66T, Ireland.
Tomasz
T
Ochalski
AMBER, CRANN, Trinity College Dublin, Dublin D02 R590, Ireland.
Michael A
MA
Morris
Materials Chemistry &Analysis Group, Department of Chemistry, Tyndall National Institute, University College Cork, Cork T12 YF78, Ireland.|AMBER, CRANN, Trinity College Dublin, Dublin D02 R590, Ireland.
Justin D
JD
Holmes