TY - JOUR
T1 - Aluminum-Catalyzed Growth of Silicon Nanowires in High-Energy Growth Directions
AU - Hainey, Mel F.
AU - Zhang, Xiaotian
AU - Wang, Ke
AU - Redwing, Joan M.
PY - 2018/10/26
Y1 - 2018/10/26
N2 - Silicon nanowires grown by metal-mediated techniques, such as vapor-liquid-solid growth, typically exhibit a predominant <111> growth direction; however, growth in the <110> and other high-energy directions is also desirable due to their predicted superior transport properties compared to those of <111> wires. In the case of aluminum-catalyzed silicon nanowire growth via chemical vapor deposition (CVD), <110> wire growth has been previously demonstrated; however, the conditions promoting <110> growth over <111> growth are not fully understood. In this report, we demonstrate that variations in precursor partial pressure within the CVD reactor play a significant role in determining the wire growth direction in this process. In the case of growth on Si(110) substrates, the preferential wire growth direction changes from <111> to <110> along the reactor tube length, corresponding to a reduction in the SiH4 gas-phase concentration due to gas-phase depletion as predicted from computational fluid dynamics simulations. While the change in growth direction occurs without a substantial reduction in the wire growth rate, significant changes occur in the shape of the aluminum-catalyst tip, suggesting a change in growth mechanism arising from possible changes in catalyst supersaturation and/or nanowire sidewall termination. Finally, the identified growth window for <110> wires is used to demonstrate <100> wire growth on Si(100) substrates.
AB - Silicon nanowires grown by metal-mediated techniques, such as vapor-liquid-solid growth, typically exhibit a predominant <111> growth direction; however, growth in the <110> and other high-energy directions is also desirable due to their predicted superior transport properties compared to those of <111> wires. In the case of aluminum-catalyzed silicon nanowire growth via chemical vapor deposition (CVD), <110> wire growth has been previously demonstrated; however, the conditions promoting <110> growth over <111> growth are not fully understood. In this report, we demonstrate that variations in precursor partial pressure within the CVD reactor play a significant role in determining the wire growth direction in this process. In the case of growth on Si(110) substrates, the preferential wire growth direction changes from <111> to <110> along the reactor tube length, corresponding to a reduction in the SiH4 gas-phase concentration due to gas-phase depletion as predicted from computational fluid dynamics simulations. While the change in growth direction occurs without a substantial reduction in the wire growth rate, significant changes occur in the shape of the aluminum-catalyst tip, suggesting a change in growth mechanism arising from possible changes in catalyst supersaturation and/or nanowire sidewall termination. Finally, the identified growth window for <110> wires is used to demonstrate <100> wire growth on Si(100) substrates.
UR - http://www.scopus.com/inward/record.url?scp=85074895401&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=85074895401&partnerID=8YFLogxK
U2 - 10.1021/acsanm.8b00925
DO - 10.1021/acsanm.8b00925
M3 - Article
AN - SCOPUS:85074895401
VL - 1
SP - 5493
EP - 5499
JO - ACS Applied Nano Materials
JF - ACS Applied Nano Materials
SN - 2574-0970
IS - 10
ER -