Supplementary Information
Color Imaging via Nearest Neighbor
Hole Coupling in Plasmonic Color
Filters Integrated onto a
Complementary Metal-Oxide
Semiconductor Image Sensor
Stanley P. Burgos,†,§ Sozo Yokogawa,†,‡,§ and Harry A. Atwater†,*
†
‡
§
*
California Institute of Technology, 1200 East California Boulevard, Pasadena, California 91125, United States, and
Sony Corporation, Atsugi Tec. 4-14-1 Asahi-cho, Atsugi, Kanagawa 243-0014, Japan.
Equal author contribution.
Address correspondence to [email protected].
SUPPLERMENTARY FIGURES
= 400 nm
b)
a)
10
|
2
x 10
c)
'| = 6.1
1.7
23
12
13
3
24
6
4
2
1
34
14
'[
1
Efficiency (T/T0 )
|
'=
8
'|
0
1.5
4
1
FDTD
Model
0.5
200
400
600
800
Pitch (nm)
1000
1200
0
400
500
600
Wavelength(nm)
700
800
Figure S1. (b) Transmission efficiency as a function of pitch for a symmetric 4-hole triangularlattice unit cell (a), consisting of 180 nm diameter holes set at a pitch of 340 nm in a 150 nm thick
Al film embedded in SiO2. The red dotted spectrum is extracted from FDTD simulations and the
blue dashed spectrum corresponds to the fitted scattering-absorption model. The horizontal
dashed curve at ‘1’ corresponds to the normalized transmission efficiency of a single isolated
hole. (c) Spectrally resolved scattering-absorption parameters obtained by varying the
wavelength from 400−800 nm and fitting as done in (b).
1
6
FDTD
3rd n.n.
0
Efficiency(T/T )
5
2nd n.n.
4
3
2
1
0
400
500
600
Wavelength(nm)
700
800
Figure S2. Transmission efficiency for different hole array configurations as a function of number
of contributing nearest neighbors (n.n.). Data is shown for spectra calculated with FDTD as well
as with the nearest-neighbor scattering model with second and third n.n. contributions. The hole
array configurations (see insets) consist of 180 nm diameter holes set at a pitch of 380 nm in a
150 nm thick Al film embedded in SiO2.
3
0.7
Efficiency (T/T0 )
360 nm
340 nm
2.5
320 nm
300 nm
2
b)
d=180nm
380 nm
400 nm
0.6
Absolute Transmission
a)
1.5
1
0.5
0
400
0.5
0.4
p=340nm
d=200nm
d=180nm
d=160nm
0.3
0.2
0.1
500
600
Wavelength (nm)
700
800
0
400
500
600
Wavelength (nm)
700
800
Figure S3. (a) Normalized transmission efficiency curves extracted from the scattering model as a
2
function of array pitch for a ~10 × 10 μm square-shaped triangular-lattice hole array consisting of
180 nm diameter holes in a 150 nm thick Al film embedded in SiO2. (b) Absolute transmission
efficiency extracted from FDTD for an infinite triangular-lattice hole array as a function of hole
diameter for an array consisting of 340 nm pitch holes in a 150 nm Al film embedded in SiO2.
2
a) Thin Cr layer
b) PMMA
c) EPBG
f) Lift-off
e) Al layer
d) Develop
g) Spin-on-glass (SOG)
h) RGB filter array
k) Contact
i) CMOS IS
Quartz
Cr
j) PMMA
PMMA
Al
SOG
Si
Si3N4
Cu
Figure S4. Fabrication and integration of hole array filter with CMOS image sensor. (a) Thin layer
of Cr is deposited on quartz substrate to reduce charging during electron-beam writing of the
hole array color filter pattern. (b) PMMA is spin coated on top of Cr layer. (c) PMMA is exposed
using electron-beam lithography. (d) Exposed PMMA pattern is developed. (e) Al layer is
deposited to form hole array pattern. (f) PMMA is lifted off. (g) Spin-on-glass (SOG) is spin coated
over Al pattern. (h) Resulting pattern is RGB hole array color filter in Bayer layout. (i) CMOS image
sensor is (j) spin coated with PMMA to planarize the microlenses. (k) Hole array filter is contacted
onto planarized CMOS IS.
3
Figure S5. Alignment of plasmonic hole array filter with CMOS image sensor. The lined grid
represents the pixel array of the CMOS image sensor and the transparent RGB box grid
represents the plasmonic hole array color filter array in Bayer layout. The pixels are labeled using
matrix convention (i, j) with i coming from the horizontal axis and j coming from the vertical axis,
and the double letters inside of the grid refer to the parity of the pixel label, with E for even and O
for odd. Pixel and filter array are shown with (a) perfect alignment, (b) translational offset, and (c)
rotational offset. (d) Image readout of the difference parity set of pixels: even-even (EE), even-odd
(EO), odd-even (OE), and odd-odd (OO), after demosaicing a gray wall image taken with the CMOS
image sensor integrated with the aligned hole array color filters.
4
Effect of Color Crosstalk on Bayer Mosaic Layout Unit Cell
Effect of Bayer Mosaic Layout on Hole Array Color Filters
R
RBayer
G
GBayer
R
BBayer
0.8
0.6
0.4
0.2
0
400
1
Normalized Transmission
Normalized Transmission
1
a)
b)
R
R
G
R
G
G
0.8
0.6
0.4
0.2
450
500
550
600
650
Wavelength (nm)
700
750
800
0
400
450
500
550
600
650
Wavelength (nm)
700
750
800
Figure S6. Normalized FDTD-calculated transmission efficiencies for triangular-lattice hole arrays
corresponding to red (p = 420 nm, d = 240 nm), green (p = 340 nm, d = 180 nm), and blue (p = 260
nm, d = 140 nm) filers in a 150 nm Al film embedded in SiO2. (a) Transmission response of a
2
periodic 11.2 × 11.2 μm RGB hole array color filter Bayer unit cell (similar to that shown in Fig.
2
S2b, comprised of 5.6 × 5.6 μm RGB hole array color filters with zero separation between color
patches) compared to the transmission of infinite RGB hole array filters (simulated with Bloch
boundary conditions as described in Methods). (b) Transmission response of a periodic 11.2 ×
2
11.2 μm RGB hole array color filter Bayer unit cell in which the transmission for each color filter
is monitored both right underneath the Bayer unit cell (z = 0 μm) and at z = −1 μm, where the
focusing micro-lenses are located in the device simulations. The transmission of each color filter
is monitored with a set of transmission monitors that have physical extent corresponding to the
physical size of the corresponding RGB color filters, thus corresponding to the amount of light
captured by the micro-lenses of each color filter.
5
a)
6mm, F5.6
b)
9mm, F5.6
e)
f)
Watson Patio, Caltech
c)
12.5mm, F5.6
d)
50mm, F5.6
g)
Beckman Auditorium, Caltech
h)
Atwater Group, Aug 2012
Red Door Cafe, Caltech
Figure S7. Focal length dependence and outdoor lighting conditions. Images of 24-color Macbeth
char positioned in a scene taken with CMOS image sensor integrated with RGB plasmonic hole
array filter with a 5.6 f-number and a (a) 6 mm, (b) 9 mm, (c) 12.5 mm, and (d) 50 mm lens. Images
taken with outdoor lighting conditions of (e) Watson Patio, Caltech, (f) Beckman Auditorium,
Caltech, (g) Atwater Group, Aug. 2012, Caltech, and (h) Red Door Café, Caltech.
6