Controlling the light reflection using vertically-aligned nanowires has great importance in fundamental research with interesting applications in photonic devices. Here, we discuss the spatial- and polarization-dependent reflectivity measurements from the cross-sectional as well as from the top surface of vertically-aligned disordered silicon nanowires. The gradient variation in an effective refractive index along the nanowire length is estimated using the cross-sectional reflectivity measurements. We have studied the gradient variation of an effective refractive index profile and its tunability with the nanowire length. The reflectivity is measured to be as low as 5% irrespective of spatial directions and the polarization of incident light in a broad wavelength range. This constitutes the signature of a broadband omnidirectional anti-reflector that is scalable with the nanowire length. The reflectivity measurements are in good agreement with theoretical calculations. Such omnidirectional anti-reflection in a broad wavelength range is useful for applications such as photon management in photovoltaic devices and disorder-induced light scattering.

1.
A.
Polman
and
H. A.
Atwater
,
Nat. Mater.
11
,
174
(
2012
).
2.
P.
Yeh
,
Optical Waves in Layered Media
(
John Wiley & Sons
,
New Jersey
,
2005
).
3.
Y.
Fink
,
J. N.
Winn
,
S.
Fan
,
C.
Chen
,
J.
Michel
,
J. D.
Joannopoulos
, and
E. L.
Thomas
,
Science
282
,
1679
(
1998
).
4.
K.
Im
,
J.-H.
Kang
, and
Q.-H.
Park
,
Nat. Photon.
12
,
143
(
2018
).
5.
S. R.
Huisman
,
R. V.
Nair
,
A.
Hartsuiker
,
L. A.
Woldering
,
A. P.
Mosk
, and
W. L.
Vos
,
Phys. Rev. Lett.
108
,
083901
(
2012
).
6.
J.
Joannopoulos
,
S.
Johnson
,
J.
Winn
, and
R.
Meade
, Photonic Crystals: Molding the Flow of Light (Princeton University Press,
Princeton
,
1995
).
7.
S. R.
Huisman
,
R. V.
Nair
,
L. A.
Woldering
,
M. D.
Leistikow
,
A. P.
Mosk
, and
W. L.
Vos
,
Phys. Rev. B
83
,
205313
(
2011
).
8.
L. A.
Woldering
,
R. W.
Tjerkstra
,
H. V.
Jansen
,
I. D.
Setija
, and
W. L.
Vos
,
Nanotechnology
19
,
145304
(
2008
).
9.
W. C.
Stumpf
,
T.
Asano
,
T.
Kojima
,
M.
Fujita
,
Y.
Tanaka
, and
S.
Noda
,
Phys. Rev. B
82
,
075119
(
2010
).
10.
J.
Schilling
,
J.
White
,
A.
Scherer
,
G.
Stupian
,
R.
Hillebrand
, and
U.
Gösele
,
Appl. Phys. Lett.
86
,
011101
(
2005
).
11.
H. K.
Raut
,
V. A.
Ganesh
,
A. S.
Nair
, and
S.
Ramakrishna
,
Energy Environ. Sci.
4
,
3779
(
2011
).
12.
Z.
Diao
,
M.
Kraus
,
R.
Brunner
,
J.-H.
Dirks
, and
J. P.
Spatz
,
Nano Lett.
16
,
6610
(
2016
).
13.
L.
Rayleigh
,
Proc. Lond. Math. Soc.
1
,
51
(
1879
).
14.
P.
Clapham
and
M.
Hutley
,
Nature
244
,
281
(
1973
).
15.
R. H.
Siddique
,
G.
Gomard
, and
H.
Hölscher
,
Nat. Commun.
6
,
6909
(
2015
).
16.
J.
Dobrowolski
,
D.
Poitras
,
P.
Ma
,
H.
Vakil
, and
M.
Acree
,
Appl. Opt.
41
,
3075
(
2002
).
17.
J.-Q.
Xi
,
M. F.
Schubert
,
J. K.
Kim
,
E. F.
Schubert
,
M.
Chen
,
S.-Y.
Lin
,
W.
Liu
, and
J. A.
Smart
,
Nat. Photon.
1
,
176
(
2007
).
18.
Y.-F.
Huang
,
S.
Chattopadhyay
,
Y.-J.
Jen
,
C.-Y.
Peng
,
T.-A.
Liu
,
Y.-K.
Hsu
,
C.-L.
Pan
,
H.-C.
Lo
,
C.-H.
Hsu
,
Y.-H.
Chang
,
C.-S.
Lee
,
K.-H.
Chen
, and
L.-C.
Chen
,
Nat. Nanotechnol.
2
,
770
(
2007
).
19.
S. L.
Diedenhofen
,
G.
Vecchi
,
R. E.
Algra
,
A.
Hartsuiker
,
O. L.
Muskens
,
G.
Immink
,
E. P.
Bakkers
,
W. L.
Vos
, and
J. G.
Rivas
,
Adv. Mater.
21
,
973
(
2009
).
20.
M. L.
Brongersma
,
Y.
Cui
, and
S.
Fan
,
Nat. Mater.
13
,
451
(
2014
).
21.
F.
Priolo
,
T.
Gregorkiewicz
,
M.
Galli
, and
T. F.
Krauss
,
Nat. Nanotechnol.
9
,
19
(
2014
).
22.
P.
Spinelli
,
M.
Verschuuren
, and
A.
Polman
,
Nat. Commun.
3
,
692
(
2012
).
23.
C.-H.
Sun
,
P.
Jiang
, and
B.
Jiang
,
Appl. Phys. Lett.
92
,
061112
(
2008
).
24.
A.
Rahman
,
A.
Ashraf
,
H.
Xin
,
X.
Tong
,
P.
Sutter
,
M. D.
Eisaman
, and
C. T.
Black
,
Nat. Commun.
6
,
5963
(
2015
).
25.
G.-R.
Lin
,
Y.-C.
Chang
,
E.-S.
Liu
,
H.-C.
Kuo
, and
H.-S.
Lin
,
Appl. Phys. Lett.
90
,
181923
(
2007
).
26.
E.
Garnett
and
P.
Yang
,
Nano Lett.
10
,
1082
(
2010
).
27.
H.
Bao
and
X.
Ruan
,
Opt. Lett.
35
,
3378
(
2010
).
28.
E.
Dimaggio
and
G.
Pennelli
,
Nano Lett.
16
,
4348
(
2016
).
29.
C.
Xie
,
B.
Nie
,
L.
Zeng
,
F.-X.
Liang
,
M.-Z.
Wang
,
L.
Luo
,
M.
Feng
,
Y.
Yu
,
C.-Y.
Wu
,
Y.
Wu
, and
S.-H.
Yu
,
ACS Nano
8
,
4015
(
2014
).
30.
B.
Fazio
,
P.
Artoni
,
M. A.
Iatì
,
C.
D’andrea
,
M. J. L.
Faro
,
S.
Del Sorbo
,
S.
Pirotta
,
P. G.
Gucciardi
,
P.
Musumeci
,
C. S.
Vasi
,
R.
Saija
,
M.
Galli
,
F.
Priolo
, and
A.
Irrera
,
Light Sci. Appl.
5
,
e16062
(
2016
).
31.
J.
Yang
,
F.
Luo
,
T. S.
Kao
,
X.
Li
,
G. W.
Ho
,
J.
Teng
,
X.
Luo
, and
M.
Hong
,
Light Sci. Appl.
3
,
e185
(
2014
).
32.
F.
Toor
,
J. B.
Miller
,
L. M.
Davidson
,
W.
Duan
,
M. P.
Jura
,
J.
Yim
,
J.
Forziati
, and
M. R.
Black
,
Nanoscale
8
,
15448
(
2016
).
33.
A. M.
Gouda
,
N. K.
Allam
, and
M. A.
Swillam
,
RSC Adv.
7
,
26974
(
2017
).
34.
H. A.
Chaliyawala
,
Z.
Purohit
,
S.
Khanna
,
A.
Ray
,
R. K.
Pati
, and
I.
Mukhopadhyay
,
J. Appl. Phys.
123
,
213104
(
2018
).
35.
T.-H.
Pei
,
S.
Thiyagu
, and
Z.
Pei
,
Appl. Phys. Lett.
99
,
153108
(
2011
).
36.
W.
Xie
,
J.
Oh
, and
W.
Shen
,
Nanotechnology
22
,
065704
(
2011
).
37.
Z.
Huang
,
N.
Geyer
,
P.
Werner
,
J.
De Boor
, and
U.
Gösele
,
Adv. Mater.
23
,
285
(
2011
).
38.
E. D.
Palik
,
Handbook of Optical Constants of Solids
(
Academic Press
,
Boston
,
1998
), Vol. 3.
39.
H.-C.
Chang
,
K.-Y.
Lai
,
Y.-A.
Dai
,
H.-H.
Wang
,
C.-A.
Lin
, and
J.-H.
He
,
Energy Environ. Sci.
4
,
2863
(
2011
).
40.
A.
Lagendijk
,
B.
van Tiggelen
, and
D. S.
Wiersma
,
Phys. Today
62
,
24
(
2009
).
41.
H.
Zeng
,
H.
Zhao
,
F.-C.
Zhang
, and
X.
Cui
,
Phys. Rev. Lett.
102
,
136406
(
2009
).

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