Diameter-dependent dopant location in silicon and germanium nanowires.
We report studies defining the diameter-dependent location of electrically active dopants in silicon (Si) and germanium (Ge) nanowires (NWs) prepared by nanocluster catalyzed vapor-liquid-solid (VLS) growth without measurable competing homogeneous decomposition and surface overcoating. The location of active dopants was assessed from electrical transport measurements before and after removal of controlled thicknesses of material from NW surfaces by low-temperature chemical oxidation and etching. These measurements show a well-defined transition from bulk-like to surface doping as the diameter is decreased <22-25 nm for n- and p-type Si NWs, although the surface dopant concentration is also enriched in the larger diameter Si NWs. Similar diameter-dependent results were also observed for n-type Ge NWs, suggesting that surface dopant segregation may be general for small diameter NWs synthesized by the VLS approach. Natural surface doping of small diameter semiconductor NWs is distinct from many top-down fabricated NWs, explains enhanced transport properties of these NWs and could yield robust properties in ultrasmall devices often dominated by random dopant fluctuations.
Xie
Ping
P
Department of Chemistry and Chemical Biology, Harvard University, Cambridge, MA 02138, USA.
Hu
Yongjie
Y
Fang
Ying
Y
Huang
Jinlin
J
Lieber
Charles M
CM
D005857:Germanium / Q000737:chemistry*; D008422:Materials Testing; D036103:Nanotechnology / Q000379:methods*; D053770:Nanowires / Q000737:chemistry*; D012825:Silicon / Q000737:chemistry*; D013499:Surface Properties
D005857:Germanium; D012825:Silicon
Proc Natl Acad Sci U S A. 2005 Jul 19;102(29):10046-51
16006507
Nano Lett. 2009 Mar;9(3):1071-9
19226128
Nat Nanotechnol. 2008 Mar;3(3):168-73
18654490
Nano Lett. 2005 Jun;5(6):1143-6
15943458
Nature. 2005 Jul 7;436(7047):91-4
16001066
Nano Lett. 2008 Sep;8(9):2620-4
18700807
Phys Rev Lett. 2006 Apr 28;96(16):166805
16712258
Nano Lett. 2008 Oct;8(10):3109-13
18767881
Phys Rev Lett. 2006 Jun 9;96(22):226802
16803336
Anal Bioanal Chem. 2004 Jan;378(2):411-5
14634703
Science. 2005 Nov 25;310(5752):1304-7
16311329
Science. 2003 Mar 21;299(5614):1874-7
12595610
Nano Lett. 2006 Dec;6(12):2781-4
17163705
Science. 2006 Jun 9;312(5779):1504-8
16763144
Nat Nanotechnol. 2009 Feb;4(2):103-7
19197312
Nature. 2007 Oct 18;449(7164):885-9
17943126
Nature. 2004 Jul 1;430(6995):61-5
15229596
Small. 2006 Oct;2(10):1153-8
17193581
Nature. 2002 Nov 7;420(6911):57-61
12422212