TY - JOUR
T1 - Hexagonal silicon grown from higher order silanes
AU - Ren, Yizhen
AU - Leubner, Philipp
AU - Verheijen, Marcel A.
AU - Haverkort, Jos E.M.
AU - Bakkers, Erik P.A.M.
PY - 2019
Y1 - 2019
N2 - We demonstrate the merits of an unexplored precursor, tetrasilane (Si4H10), as compared to disilane (Si2H6) for the growth of defect-free, epitaxial hexagonal silicon (Si). We investigate the growth kinetics of hexagonal Si shells epitaxially around defect-free wurtzite gallium phosphide (GaP) nanowires. Two temperature regimes are identified, representing two different surface reaction mechanisms for both types of precursors. Growth in the low temperature regime (415 °C-600 °C) is rate limited by interaction between the Si surface and the adsorbates, and in the high temperature regime (600 °C-735 °C) by chemisorption. The activation energy of the Si shell growth is 2.4 ±0.2 eV for Si2H6 and 1.5 ±0.1 eV for Si4H10 in the low temperature regime. We observe inverse tapering of the Si shells and explain this phenomenon by a basic diffusion model where the substrate acts as a particle sink. Most importantly, we show that, by using Si4H10 as a precursor instead of Si2H6, non-tapered Si shells can be grown with at least 50 times higher growth rate below 460 °C. The lower growth temperature may help to reduce the incorporation of impurities resulting from the growth of GaP.
AB - We demonstrate the merits of an unexplored precursor, tetrasilane (Si4H10), as compared to disilane (Si2H6) for the growth of defect-free, epitaxial hexagonal silicon (Si). We investigate the growth kinetics of hexagonal Si shells epitaxially around defect-free wurtzite gallium phosphide (GaP) nanowires. Two temperature regimes are identified, representing two different surface reaction mechanisms for both types of precursors. Growth in the low temperature regime (415 °C-600 °C) is rate limited by interaction between the Si surface and the adsorbates, and in the high temperature regime (600 °C-735 °C) by chemisorption. The activation energy of the Si shell growth is 2.4 ±0.2 eV for Si2H6 and 1.5 ±0.1 eV for Si4H10 in the low temperature regime. We observe inverse tapering of the Si shells and explain this phenomenon by a basic diffusion model where the substrate acts as a particle sink. Most importantly, we show that, by using Si4H10 as a precursor instead of Si2H6, non-tapered Si shells can be grown with at least 50 times higher growth rate below 460 °C. The lower growth temperature may help to reduce the incorporation of impurities resulting from the growth of GaP.
KW - activation energy
KW - core/shell nanowires
KW - hexagonal silicon
KW - higher order silanes
KW - silicon epitaxy
UR - http://www.scopus.com/inward/record.url?scp=85065510081&partnerID=8YFLogxK
U2 - 10.1088/1361-6528/ab0d46
DO - 10.1088/1361-6528/ab0d46
M3 - Article
C2 - 30840942
AN - SCOPUS:85065510081
SN - 0957-4484
VL - 30
JO - Nanotechnology
JF - Nanotechnology
IS - 29
M1 - 295602
ER -