Single crystalline and core-shell indium-catalyzed germanium nanowires-a systematic thermal CVD growth study.
Germanium nanowires were synthesized using thermal chemical vapor deposition (CVD) and indium as a catalyst. The process parameter space for successful growth was studied. By optimizing the growth temperature and gas pressure, high aspect ratio germanium nanowires have been obtained. Scanning electron microscopy investigations indicate that the final diameter of the nanowires is strongly influenced by the growth temperature and the germane partial pressure. High resolution transmission electron microscopy reveals that nanowires grow either as high quality single crystalline, or with a high quality single-crystalline core and a concentric amorphous shell. The occurrence of these two morphologies is found to only depend on the wire diameter. Chemical analysis of the nanowire tip indicates the presence of indium, validating its role as a catalyst. Raman spectroscopy measurements reveal a higher incidence of core-shell structures for nanowires synthesized at 30 Torr and indicate the presence of tensile strain. These results are important towards obtaining high quality germanium nanowires without the use of gold as a catalyst, which is known to degrade the wires' electrical and optical properties.
Xiang
Ying
Y
Walter Schottky Institut, Technische Universität München, Am Coulombwall 3, D-85748 Garching, Germany.
Cao
Linyou
L
Conesa-Boj
Sonia
S
Estrade
Sonia
S
Arbiol
Jordi
J
Peiro
Francesca
F
Heiss
Martin
M
Zardo
I
I
Morante
Joan R
JR
Brongersma
Mark L
ML
Fontcuberta I Morral
Anna
A
D002384:Catalysis; D003460:Crystallization / Q000379:methods*; D005740:Gases; D005857:Germanium / Q000737:chemistry*; D006358:Hot Temperature; D007204:Indium / Q000737:chemistry*; D046911:Macromolecular Substances / Q000737:chemistry; D008422:Materials Testing; D008968:Molecular Conformation; D049329:Nanostructures / Q000737:chemistry* / Q000648:ultrastructure*; D036103:Nanotechnology / Q000379:methods*; D010316:Particle Size; D013499:Surface Properties
D005740:Gases; D046911:Macromolecular Substances; D005857:Germanium; D007204:Indium