Supporting Materials
SERS and FDTD Simulation of Gold Nanoparticles Grafted on
Germanium Wafer via Galvanic Displacement
Zhaoshun Zhang, Fan Liao*, Shuzhen Ma, Suning Gao, Mingwang Shao*
Institute of Functional Nano & Soft Materials (FUNSOM), Soochow University, Suzhou 215123, P.
R. China
1. Statistics of diameter and distance
The diameter distribution and inter-particle distance distribution of Au NPs
grown on Ge wafer were calculated and shown in Figure S1.
Figure S1. Histograms of the diameter distribution (a) and inter-particle distance
distribution (b) based on 100 AuNPs grown on Ge wafer. The statistics shows that the
average diameter of Au particles is 14 nm with the inter-particle distance of about 3.6
nm.
2. Calculation of Raman enhancement factor (EF)
The average SERS EF can be calculated according to the formula:
S1
EF=
ISERS N0
I 0 NSERS
where I0 and ISERS are the peak intensity of the Raman measurement with 0.01 M R6G
solution (Figure S2) and SERS measurement with 1×10-10 M R6G solution,
respectively; N0 and NSERS are the number of R6G molecules in the scattering volume
for the Raman measurement and SERS measurement, respectively. Because the
Raman experiment was conducted in the aqueous solution, N0 and NSERS could be
calculated as follows:
N 0  n0 N A  C0V0 N A
N SERS  nSERS N A  CSERSVSERS N A
where n0 and nSERS are the amount substance of R6G molecules in the scattering
volume; V0 and VSERS are the scattering volume (V0 = VSERS); C0 and CSERS are the
concentration of R6G solution. The subscripts 0 and SERS represent Raman
measurement and SERS measurement, respectively. NA is Avogadro constant.
So the EF of Au/Ge substrate can be calculated as:
967 110-2
I SERS N 0
I SERS C0V0 N A
I SERS C0
EF 


= 281 1 10 -8 = 3.44 × 106
I 0 N SERS I 0CSERSVSERS N A I 0CSERS
Figure S2. The normal Raman spectrum of 0.01 M R6G methanol solution.
S2