Unveiling the formation pathway of single crystalline porous silicon nanowires.
Porous silicon nanowire is emerging as an interesting material system due to its unique combination of structural, chemical, electronic, and optical properties. To fully understand their formation mechanism is of great importance for controlling the fundamental physical properties and enabling potential applications. Here we present a systematic study to elucidate the mechanism responsible for the formation of porous silicon nanowires in a two-step silver-assisted electroless chemical etching method. It is shown that silicon nanowire arrays with various porosities can be prepared by varying multiple experimental parameters such as the resistivity of the starting silicon wafer, the concentration of oxidant (H(2)O(2)) and the amount of silver catalyst. Our study shows a consistent trend that the porosity increases with the increasing wafer conductivity (dopant concentration) and oxidant (H(2)O(2)) concentration. We further demonstrate that silver ions, formed by the oxidation of silver, can diffuse upwards and renucleate on the sidewalls of nanowires to initiate new etching pathways to produce a porous structure. The elucidation of this fundamental formation mechanism opens a rational pathway to the production of wafer-scale single crystalline porous silicon nanowires with tunable surface areas ranging from 370 to 30 m(2) g(-1) and can enable exciting opportunities in catalysis, energy harvesting, conversion, storage, as well as biomedical imaging and therapy.
Department of Chemistry and Biochemistry, University of California, Los Angeles, California 90095, USA.
Xing
X
Zhong
Yongquan
Y
Qu
Yung-Chen
YC
Lin
Lei
L
Liao
Xiangfeng
X
Duan
D002384:Catalysis; D004553:Electric Conductivity; D006861:Hydrogen Peroxide / Q000737:chemistry; D008854:Microscopy, Electron; D036103:Nanotechnology / Q000379:methods*; D053770:Nanowires / Q000737:chemistry* / Q000648:ultrastructure; D010316:Particle Size; D016062:Porosity; D012825:Silicon / Q000737:chemistry*
D006861:Hydrogen Peroxide; D012825:Silicon
Nano Lett. 2006 Dec;6(12):2929-34
17163733
Adv Funct Mater. 2010 Jul 23;20(14):2231-2239
21057669
Nat Nanotechnol. 2008 Jan;3(1):31-5
18654447
Chem Commun (Camb). 2009 Jan 8;(2):195-7
19099066
Chem Rev. 2010 Jan;110(1):527-46
19817361
Nano Lett. 2009 Jan;9(1):410-5
19053790
Nano Lett. 2009 Jan;9(1):491-5
19105648
Science. 2006 Aug 25;313(5790):1100-4
16931757
Nano Lett. 2008 Jan;8(1):265-70
18072799
ACS Nano. 2010 Mar 23;4(3):1443-50
20201547
Nature. 2007 Oct 18;449(7164):885-9
17943126
Nano Lett. 2009 Dec;9(12):4539-43
19807130
Nano Lett. 2010 Mar 10;10(3):1082-7
20108969
J Mater Chem. 2010;20(18):3590-3594
22190767
Nano Lett. 2008 Sep;8(9):3046-51
18698834
Nano Lett. 2009 Nov;9(11):3704-9
19807069
J Am Chem Soc. 2008 Jul 23;130(29):9224-5
18576622
Nature. 2000 Nov 23;408(6811):440-4
11100719
Small. 2005 Nov;1(11):1062-7
17193395
Nature. 2008 Jan 10;451(7175):163-7
18185582
Nat Mater. 2009 Apr;8(4):331-6
19234444
Nano Lett. 2010 May 12;10(5):1529-36
20394412
Angew Chem Int Ed Engl. 2005 Apr 29;44(18):2737-2742
15812791
Nano Lett. 2009 Oct;9(10):3550-4
19824705
Science. 2001 Nov 9;294(5545):1313-7
11701922
Nat Biotechnol. 2005 Oct;23(10):1294-301
16170313