Ordered arrays of vertically aligned [110] silicon nanowires by suppressing the crystallographically preferred <100> etching directions.
The metal-assisted etching direction of Si(110) substrates was found to be dependent upon the morphology of the deposited metal catalyst. The etching direction of a Si(110) substrate was found to be one of the two crystallographically preferred 100 directions in the case of isolated metal particles or a small area metal mesh with nanoholes. In contrast, the etching proceeded in the vertical [110] direction, when the lateral size of the catalytic metal mesh was sufficiently large. Therefore, the direction of etching and the resulting nanostructures obtained by metal-assisted etching can be easily controlled by an appropriate choice of the morphology of the deposited metal catalyst. On the basis of this finding, a generic method was developed for the fabrication of wafer-scale vertically aligned arrays of epitaxial [110] Si nanowires on a Si(110) substrate. The method utilized a thin metal film with an extended array of pores as an etching catalyst based on an ultrathin porous anodic alumina mask, while a prepatterning of the substrate prior to the metal depostion is not necessary. The diameter of Si nanowires can be easily controlled by a combination of the pore diameter of the porous alumina film and varying the thickness of the deposited metal film.
Huang
Zhipeng
Z
Max Planck Institute of Microstructure Physics, Weinberg 2, D-06120 Halle, Germany. zhuang@mpi-halle.mpg.de
Shimizu
Tomohiro
T
Senz
Stephan
S
Zhang
Zhang
Z
Zhang
Xuanxiong
X
Lee
Woo
W
Geyer
Nadine
N
Gösele
Ulrich
U
D002384:Catalysis; D003460:Crystallization; D008855:Microscopy, Electron, Scanning; D053770:Nanowires / Q000737:chemistry*; D016062:Porosity; D012825:Silicon / Q000737:chemistry*; D012834:Silver / Q000737:chemistry*
D012834:Silver; D012825:Silicon