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CONFIDENTIAL<br />
© 2011 Attolight AG. All Rights Reserved.<br />
CONFIDENTIAL<br />
1
attolight<br />
<br />
CONFIDENTIAL<br />
Attolight AG<br />
EPFL Innovation Square<br />
PSE D<br />
1015 Lausanne<br />
Switzerland<br />
t +41 21 626 0100<br />
March 21, 2013<br />
The Attolight CL System<br />
www.attolight.com<br />
Jean Berney<br />
Attolight AG Switzerland / www.attolight.com<br />
© 2013 Attolight AG. All Rights Reserved.<br />
2
Who are we<br />
CONFIDENTIAL<br />
Swiss<br />
Company<br />
Spin-Off of EPFL<br />
Swiss Federal Institute of Technology<br />
Located in PSE on EPFL campus<br />
over 100 companies<br />
© 2013 Attolight AG. All Rights Reserved.<br />
3
Introduction<br />
CONFIDENTIAL<br />
Cathodoluminescence refers to the light<br />
emitted by a sample under electron<br />
irradiation.<br />
An e-beam generates several signals<br />
• Back Scattered Electrons (BSE)<br />
BSE<br />
primary e - beam<br />
SE<br />
• X Rays<br />
• Secondary Electrons (SE)<br />
• Cathodoluminescence (CL)<br />
• Auger electrons<br />
• ....<br />
X rays<br />
CL<br />
© 2013 Attolight AG. All Rights Reserved.<br />
4
Introduction<br />
CONFIDENTIAL<br />
Text<br />
• Level 1<br />
Cathodoluminescence (CL) is a Spectroscopy method<br />
featuring nanometer spatial resolution<br />
study • Level of nanometer 2 sized structures<br />
100 nm<br />
study of crystallographic<br />
defects<br />
5 µm<br />
TiO2 nanoparticles for solar cells<br />
TDs on GaN surface<br />
© 2013 Attolight AG. All Rights Reserved.<br />
5
Traditional CL approach<br />
CONFIDENTIAL<br />
Cathodoluminescence in a SEM<br />
• Acquire an SEM<br />
• Buy a CL add-on (light collection mirror<br />
and detection system) and combine<br />
Major drawbacks<br />
• At least two manufacturers involved<br />
• Interfacing difficulties, especially at low<br />
temperature<br />
• Cumbersome alignment, unstable<br />
+<br />
© 2013 Attolight AG. All Rights Reserved.<br />
6
Attolight CL System<br />
Integrated Cathodoluminescence<br />
CONFIDENTIAL<br />
• One System - One Supplier<br />
• Hybrid Microscope<br />
• Optimized for CL<br />
• Low beam energy<br />
• High flexibility<br />
• Easy to use<br />
© 2013 Attolight AG. All Rights Reserved.<br />
7
© 2012 Attolight AG. All Rights Reserved.<br />
• NO clean room environment<br />
• Fast installation in less than 24<br />
hours<br />
• Remote control interface
Attolight CL System<br />
Embedded Optical Microscope<br />
CONFIDENTIAL<br />
• Zero Alignment<br />
High Stability<br />
• Achromatic<br />
UV - IR without realignment<br />
• High Aperture (NA 0.71)<br />
Highest Collection Efficiency<br />
• Evolutive Optical System<br />
Optical Hub to easily interface<br />
PL, µPL, Raman, ...<br />
• Large Field of View<br />
Quantitative Measurements &<br />
Optical Imaging<br />
Attolight CL<br />
FOV 300µm<br />
OM 300µm<br />
FOV<br />
Standard CL<br />
Focal Spot<br />
© 2013 Attolight AG. All Rights Reserved.<br />
9
Attolight CL System<br />
Cryogenic Nanopositioning Stage<br />
CONFIDENTIAL<br />
• Helium Cryostat<br />
Allows for temperature<br />
dependent studies 15K - 300K<br />
• SEM optimized Designed<br />
Low vibration and low drift<br />
• 6-degrees-of-freedom<br />
positioning stage<br />
All possible degrees of freedom<br />
& Pivot Point Lock<br />
© 2013 Attolight AG. All Rights Reserved.<br />
10
Attolight CL System<br />
Time-Resolved Cathodoluminescence<br />
CONFIDENTIAL<br />
SE<br />
• Optimized for pulsed operation<br />
No degradation of spatial<br />
resolution in pulsed mode<br />
• Field upgradable<br />
Upgrade from standard system<br />
can be done in the user<br />
laboratory<br />
• New dimension to your data<br />
Measure local lifetime and<br />
charge carrier dynamics<br />
intensity (a.u.)<br />
100<br />
10<br />
0 400 800 1200<br />
time (ps)<br />
© 2013 Attolight AG. All Rights Reserved.<br />
11
Attolight CL System<br />
Intuitive control interface<br />
CONFIDENTIAL<br />
• Computer controlled switching<br />
between measurement modes<br />
• UV - IR without re-alignment<br />
• Remote control and<br />
surveillance<br />
• Open data format to read on<br />
any platform<br />
• Fast user training, ideal for<br />
multi-user facility<br />
• Easy to use touch screen based<br />
control console<br />
© 2013 Attolight AG. All Rights Reserved.<br />
12
Applications<br />
Gallium Arsenide single photon emitters<br />
CONFIDENTIAL<br />
AlGaAs Quantum Dots in<br />
Core-Shell Nanowires<br />
• GaAs QDs embedded in<br />
AlGaAs shell<br />
• Emission Range 620 nm<br />
- 750 nm<br />
(1 -1 2)<br />
(-2 -1 1)<br />
(1 2 1)<br />
GaAs AlGaAs (Al rich) AlGaAs (Al poor) (Al)GaAs QD<br />
«Self-assembled quantum dots in a nanowire system for quantum photonics», Heiss, Fontcuberta, Fontana et al.,<br />
Nature Mater. 2013<br />
© 2013 Attolight AG. All Rights Reserved.<br />
13
Applications<br />
Gallium Arsenide single photon emitters<br />
CONFIDENTIAL<br />
2500<br />
GaAs<br />
blue: QDs<br />
red: GaAs core<br />
2000<br />
CL Intensity (counts)<br />
1500<br />
1000<br />
QDs<br />
500 nm<br />
500<br />
Conditions<br />
0<br />
600<br />
700<br />
800<br />
Wavelength (nm)<br />
900<br />
• T = 10K, controlled<br />
• 5 keV<br />
• 1 ms / spectrum<br />
1 µm<br />
• 128 x 128 spectra<br />
• measurement time < 2 min<br />
© 2013 Attolight AG. All Rights Reserved.<br />
14
Applications<br />
Sulfur diffusion in CdTe Solar Cell Junction<br />
CONFIDENTIAL<br />
CdTe<br />
Cd(Te,S)<br />
CdS<br />
Clear interdiffusion of sulfur a the solar cell junction<br />
Dr. Aidan Taylor, Researcher of thin film materials, Durham University<br />
© 2013 Attolight AG. All Rights Reserved.<br />
15
Applications<br />
Carrier diffusion length in Diamond<br />
CONFIDENTIAL<br />
• CL line mapping on FIB lamella<br />
• Exciton diffusion in Boron<br />
doped diamond<br />
• Measurement of diffusion<br />
length in function of dopant<br />
concentration<br />
José Pinero, Specialist on high power device application of diamond, University of Cadiz, paper submitted for publication.<br />
© 2013 Attolight AG. All Rights Reserved.<br />
16
Applications<br />
Strain analysis in Zinc Oxide<br />
CONFIDENTIAL<br />
SE<br />
spectral shifts of exciton peak depending on local strain<br />
386 nm<br />
CL<br />
384 nm<br />
100µm<br />
382 nm<br />
380 nm<br />
378 nm<br />
Xuewen Fu, Specialist on electronic and mechanical coupling an applications of ZnO nanowires, Beijing University<br />
© 2013 Attolight AG. All Rights Reserved.<br />
17
Applications / Production<br />
Validation of new product generation<br />
CONFIDENTIAL<br />
GaN based alloys for power<br />
electronics<br />
• Verification of growth<br />
homogeneity<br />
• Each AlGaN layer emits at a<br />
different wavelength<br />
CL<br />
SE<br />
5 µm<br />
Rapid qualification of new<br />
designs and fabrication<br />
processes<br />
© 2013 Attolight AG. All Rights Reserved.<br />
18
Applications / Production<br />
Qualification of LED substrates<br />
CONFIDENTIAL<br />
• TDs show as dark spot due to<br />
non-radiative recombination in<br />
their vicinity<br />
• Easy measure of TDD<br />
• TDD ≃ 30 ⨉ 10 6 cm -2<br />
10µm<br />
10µm<br />
SE<br />
LED failure analysis<br />
CL<br />
© 2013 Attolight AG. All Rights Reserved.<br />
19
Applications<br />
Failure analysis on Silicon<br />
X 2.4K<br />
SE<br />
CONFIDENTIAL<br />
Detection of defects at 1.6 µm in<br />
Silicon<br />
4<br />
3<br />
Exciton peak<br />
6<br />
Defect<br />
20 µm<br />
2<br />
5<br />
1000<br />
8<br />
7<br />
6<br />
Intensity (a.u.)<br />
100<br />
5<br />
4<br />
3<br />
2<br />
8<br />
7<br />
6<br />
5<br />
Intensity (a.u.)<br />
3x10 2 4<br />
4<br />
3<br />
1000<br />
1050<br />
1100<br />
1150<br />
Wavelength (nm)<br />
1200<br />
1500<br />
1550<br />
1600<br />
Wavelength (nm)<br />
1650<br />
1700<br />
© 2013 Attolight AG. All Rights Reserved.<br />
20
Applications<br />
Local Lifetime Measurements - ZnO<br />
CONFIDENTIAL<br />
Nanobelts<br />
Text<br />
• Level 1<br />
• Level 2<br />
XX<br />
D o X<br />
X<br />
Intensity (arb. units)<br />
• Week emission from the green band at<br />
300K<br />
• well resolved excitionic transmission<br />
=> excellent material for optoelectronics <br />
3.28 3.30 3.32 3.34 3.36 3.38 3.40 3.42 3.44 3.46<br />
© 2013 Attolight AG. All Rights Reserved.
Applications<br />
CONFIDENTIAL<br />
Local Lifetime Measurements - ZnO Nanobelts<br />
CL energy shift (10 meV)<br />
CL intensity fluctuation<br />
© 2013 Attolight AG. All Rights Reserved.
Applications<br />
CONFIDENTIAL<br />
Local Lifetime Measurements - ZnO Nanobelts<br />
Exciton CL decay<br />
constant t rad<br />
I X<br />
(t)∝ 1 )<br />
Exp+<br />
−t<br />
τ r * +<br />
# 1<br />
% + 1<br />
$ τ r<br />
τ nr<br />
I X<br />
(0)∝ 1 η = τ nr<br />
τ r τ r<br />
+τ nr<br />
Local variation of exciton non-radiative<br />
lifetime along the nanobelt axis<br />
&<br />
(<br />
'<br />
−1<br />
,<br />
.<br />
-.<br />
non-radiative lifetime<br />
100%<br />
87%<br />
77%<br />
60%<br />
53%<br />
40%<br />
Excitation spot<br />
© 2013 Attolight AG. All Rights Reserved.
energy (nm)<br />
Applications<br />
Wide bandgap material<br />
CONFIDENTIAL<br />
Other Spectroscopy Tools<br />
Attolight CL<br />
• expensive (far UV)<br />
• low spatial resolution<br />
• difficult to use<br />
• not versatile<br />
260<br />
230<br />
Boron Nitride<br />
200<br />
0 200 400<br />
time (ps)<br />
© 2013 Attolight AG. All Rights Reserved.<br />
24
attolight<br />
Attolight AG<br />
EPFL Innovation Square<br />
PSE D<br />
1015<br />
Description<br />
Lausanne<br />
Switzerland<br />
t<br />
The<br />
+41<br />
core<br />
21 626<br />
piece<br />
0100<br />
of Attolight's instrument is a<br />
custom designed scanning electron microscope<br />
www.attolight.com<br />
(SEM). SEM is a widely used scanning probe<br />
technology since it has the ability to image the<br />
surface features of a sample with very high<br />
spatial resolutions going below one nanometer<br />
(10 -9 m) today. An SEM consists of an electron<br />
source and electron optics that focuses the<br />
electron beam to a nanometer sized spot. The<br />
image (or map) is constructed by scanning the<br />
electron beam over the sample point by point<br />
(see Fig. 1). The impinging electron beam on<br />
the sample surface creates secondary electrons<br />
and photons that are emitted. At each scanned<br />
point on the sample, the intensity of the secondary<br />
electron (SE) signal is recorded and a<br />
pixel is shown on the screen with a grey scale<br />
level proportional to the SE signal intensity.<br />
incoming<br />
electron beam<br />
TECHNOLOGY BRIEF<br />
Attolight uses a proprietary technology to create<br />
ultrashort electron pulses instead of a continuous<br />
electron beam (see Fig. 2). The SEM<br />
and electron source have to be custom designed<br />
to reach high spatial resolutions and<br />
short pulses. Our new tool will deliver a few<br />
nanometers spatial resolution and pulses<br />
shorter than 10 picoseconds (1 picosecond =<br />
10 -12 s) at a repetition rate of typical 80 MHz<br />
(repetition rate can be changed easily). The<br />
photoelectric effect is used to create such short<br />
electron pulses: short UV laser pulses are sent<br />
on a thin metal film which creates short electron<br />
pulses. The design and manufacturing of<br />
the electron source is a core competence of<br />
Attolight. A lot of care has to be taken in designing<br />
the electron source and the electron<br />
optics in order to keep the pulses short and<br />
well focused and still intense enough to carry<br />
out measurements.<br />
electrons<br />
incoming<br />
electron beam<br />
Sample<br />
light<br />
Fig. 2 Attolight technology<br />
electrons<br />
Sample<br />
light<br />
Fig. 1 Principle of standard SEM<br />
Time resolved spectroscopy<br />
This is our “home” application in the R&D market.<br />
Initially, the tool was built for this application.<br />
We exploit a phenomena called cathodoluminescence<br />
(CL): some semiconductors emit<br />
light when they are bombarded with an electron<br />
beam containing electrons carrying a certain<br />
energy. This light is called CL and contains<br />
a lot of information on optical properties of the<br />
material under test. CL is often used to analyse<br />
semiconductor based nanostructures since the<br />
spatial resolution is very high. CL is a excitation<br />
spectroscopy technique with very high spatial<br />
resolution.<br />
Our idea was not just to look at a continuous<br />
CL signal but also at the lifetime of the signal<br />
in the picosecond regime. To achieve this we<br />
adapted an ultrafast light detector (STREAK<br />
camera) to our instrument. We call this tool<br />
pTRCL (picosecond time-resolved CL).<br />
© 2011 Attolight AG - All rights reserved.
attolight<br />
Attolight AG<br />
EPFL Innovation Square<br />
PSE D<br />
1015<br />
TRCL is<br />
Lausanne<br />
a High-Resolution Technique<br />
Switzerland<br />
t<br />
Given<br />
+41 21<br />
the<br />
626<br />
context<br />
0100<br />
of developing nanosciences,<br />
there is currently a growing interest in obtaining<br />
local information about light-emitting<br />
www.attolight.com<br />
phenomena in condensed matter. In particular,<br />
dynamical information such as the luminescence<br />
decay time is of major importance to<br />
analyse the competition between radiative and<br />
nonradiative processes in materials and nanostructures<br />
designed to serve in optoelectronic<br />
devices.<br />
However, while it is easy to measure the photoluminescence<br />
decay dynamics with a spatial<br />
resolution of a few hundreds of squared micrometers,<br />
achieving such measurements at<br />
the scale of a few tens of nanometers is still<br />
challenging.<br />
Therefore, in most instances, TR-PL experiments<br />
only provide information that is integrated<br />
over a number of light-emitting nanoobjects<br />
and over a number of competitive<br />
processes: radiative processes themselves, carrier<br />
transfer among different radiative or nonradiative<br />
centers, nonradiative carrier recombination…<br />
In the case of individual nano-objects or of<br />
materials comprising a variety of light-emitting<br />
sub-structures, such integrated information is<br />
not detailed enough and leads to conjectural<br />
analyses of the recorded data.<br />
On the other hand, thanks to a strongly localized<br />
excitation, TRCL permits to isolate (spatially<br />
and spectrally) the different light sources<br />
and to analyse their dynamical characteristics<br />
separately.<br />
Interest of Temperature-dependent TRCL<br />
Like for other spectroscopic techniques the<br />
possibility to use cryogenic temperatures has<br />
several beneficial effects.<br />
First of all, by hindering thermally-enhanced<br />
nonradiative recombinations, low temperatures<br />
increase drastically the signal-to-noise ratio.<br />
For the same reason, the CL decay dynamics<br />
measured at low-temperatures are closer (if<br />
TECHNICAL NOTE<br />
not exactly identical) to the purely radiative<br />
dynamics.<br />
Indeed, the effective decay time, τCL, is related<br />
to the radiative (τR) and nonradiative (τNR)<br />
lifetimes by: τCL =(τR-1 + τNR-1)-1. In other<br />
words, when the sample is placed at low temperatures,<br />
the nonradiative lifetime becomes<br />
so long that the effective lifetime is close to the<br />
radiative lifetime. The latter is a precious piece<br />
of information, especially in the study of lowdimensional<br />
semiconductor systems such as<br />
quantum wells or quantum dots.<br />
The second favourable effect of low temperatures<br />
is the reduction of emission linewidths.<br />
Whenever several optical transitions, corresponding<br />
to various recombination mechanisms,<br />
are close in energy, this linewidth reduction<br />
permits to separate these mechanisms.<br />
In CL, this point is quite often very profitable<br />
because the different mechanisms can correspond<br />
to different localizations in space. In<br />
TRCL, the temporal behaviours pertaining to<br />
these different mechanisms can be studied<br />
separately.<br />
The third advantage of low temperatures is<br />
that it reduces the diffusion of carriers across<br />
the sample and generally favours optical recombination<br />
of localised excitons. Consequently,<br />
the CL images obtained are sharper:<br />
the resolution, specially in monochromatic detection<br />
mode, is enhanced.<br />
There is also clearly an interest for experiments<br />
conducted under variable temperature conditions.<br />
This is particularly true when dealing<br />
with carrier diffusion/capture processes that<br />
can be studied by analysing the CL rise-times.<br />
Their behaviour when T is changed, along with<br />
the appropriate modelling, provides crucial<br />
information on diffusion coefficients, energy<br />
transfer mechanisms, activation energies…<br />
TRCL is an Excitation Spectroscopy Technique<br />
Contrary to the intuitive approach, cathodoluminescence,<br />
when seen as a mapping method,<br />
does not show, strictly speaking, where the<br />
emitted light comes from. In fact, it rather correlates,<br />
with very high resolution, the 2D coor-<br />
© 2011 Attolight AG - All rights reserved.
attolight<br />
dinates of the excitation spot with the emission<br />
of light AG by the sample, wherever this<br />
Attolight<br />
EPFL emission Innovation really takes Square place.<br />
PSE In other D words, in CL, the high resolution is a<br />
1015 unique Lausanne characteristic of the excitation, not of<br />
Switzerland<br />
the emission.<br />
t +41 21 626 0100<br />
In many cases, especially in low-quality samples,<br />
where the carrier diffusion lengths are<br />
www.attolight.com<br />
small, the<br />
above remark is of little relevance: the CL emission<br />
indeed takes place where the electronic<br />
excitation has been<br />
delivered, at least within the accuracy limited<br />
by the size of the generation volume and by<br />
the carrier diffusion lengths. Typically, a resolution<br />
of a few hundred nanometers is reached.<br />
But in high-quality samples, the situation can<br />
be totally different. For example, for the complex<br />
pyramidal quantum systems of Ref. [1],<br />
wherever the excitation spot is placed on the<br />
pyramid, the quantum dot at the tip of the<br />
pyramid is efficiently alimented by scattered<br />
carriers and it efficiently emits light at a characteristic<br />
wavelength. Therefore the CL image<br />
shows an entirely “white” pyramid although it<br />
is quite clear that light does not come from the<br />
entire pyramid, but rather from a zone that<br />
does not exceed a few nanometers at the tip of<br />
the pyramid.<br />
In this case of high-quality samples, the high<br />
diffusion length paradoxically destroys the spatial<br />
resolution of the CL experiment.<br />
Luckily, “time is on our side”: the temporal<br />
resolution provided by TRCL allows measuring<br />
the rising dynamics of luminescence signals at<br />
a given wavelength, as a function of the position<br />
of the excitation spot. It therefore provides<br />
an unprecedented insight into dynamical phenomena<br />
such as carrier diffusion and capture.<br />
In the above example, the rise-time of the CL<br />
from the tip-quantum dot is a growing function<br />
of the distance between the excitation<br />
spot and the tip and a simple model yields important<br />
characteristics such as diffusion<br />
lengths.<br />
In summary, for the study of high-quality<br />
samples where the carrier diffusion lengths are<br />
large, the time-resolution is a necessary ingredient.<br />
By careful analysis of luminescence rise-times<br />
under variable conditions of temperature and<br />
of distance from the emitting object, TRCL<br />
permits to characterize the ambipolar transport<br />
of electron-hole pairs (or excitons), which the<br />
other techniques (µPL – SNOM) cannot achieve.<br />
[1] M. Merano et al., Nature 438, 479 (2005)<br />
About the author<br />
Pierre Lefebvre<br />
Research Director at CNRS<br />
Pierre Lefebvre is a senior researcher<br />
in Physics specialized<br />
in optical properties of semiconductors,<br />
nanosciences and<br />
nanotechnology. He was the founder and first<br />
director of the Center of Competence in Nanosciences<br />
for the South-West of France. Interested<br />
in testing and promoting new concepts<br />
based on nanophysics for novel applications in<br />
optics, information technologies, solar energy.<br />
© 2011 Attolight AG - All rights reserved.
Be Part of the New<br />
Cathodoluminescence<br />
Revolution<br />
Attolight CL / Discover Quantitative Cathodoluminescence<br />
at High Space and Time Resolution<br />
Overview<br />
The Attolight CL system is the first quantitative cathodoluminescence system offering a spatial<br />
resolution below 10 nm, a field of view of 300 µm, and an optional 10 ps time resolution mode.<br />
Attolight CL combines a proprietary scanning electron microscope (SEM) with an integrated<br />
light microscope. The light microscope is embedded within the electron objective lens of the<br />
SEM so that their field of view match each other. Acquiring cathodoluminescence (CL) maps<br />
has never been easier : no optical alignment is required and the specimen is positioned thanks<br />
to the light microscope. The system is optimized to achieve superior CL performance without<br />
compromising the SEM performance. It offers an outstanding optical aperture (f/0.5), a constant<br />
and superior photon collection efficiency over the whole field of view, and a low electron beam<br />
energy range (3–10 kV) for enhanced resolution of CL maps.<br />
Attolight CL is the only system on the market that enables quantitative benchmarking of<br />
cathodoluminescence emission from one specimen to the other. Its unique ability to reveal<br />
ultra-trace impurities and crystallographic defects not visible using other imaging modes<br />
opens new possibilities for research and development of semiconductor materials, phosphor,<br />
ceramic, rock and glass.<br />
A 6-degrees-of-freedom displacement system insures arbitrary positioning of your specimen<br />
with 1 nm increments. For advanced applications requiring a deep understanding of the<br />
fundamental properties of a material or high cathodoluminescence emission efficiency,<br />
an optional cryogenic nanopositioning stage can be installed. It features temperature control<br />
between 20 K and 300 K and includes a patented mechanical design to minimize drifts<br />
and vibrations.<br />
Attolight CL is also the first cathodoluminescence microscope featuring an optional timeresolved<br />
detector with an unmatched 10 picoseconds time resolution. Time-resolved<br />
cathodoluminescence is the perfect technology for charge carrier dynamics and lifetime<br />
measurements in opto-electronic materials.<br />
Key Benefits<br />
– Zero alignment : patented achromatic light microscope<br />
embedded in the column of a proprietary scanning<br />
electron microscope<br />
– No compromise : up to 10 nm spatial resolution in both<br />
continuous and time-resolved mode from 3 kV to 10 kV<br />
– Specimen benchmarking : very large field of view (300 µm)<br />
enabling quantitative cathodoluminescence<br />
– High light collection efficiency : numerical aperture of<br />
0,71 (f/0,5)<br />
– Arbitrary movements : innovative 6-degrees-of-freedom<br />
nano-positioning stage (down to 1 nm displacement<br />
increments)<br />
– Optional innovative low vibration cryostat for temperature<br />
measurements between 20K and 300K<br />
– Optical hub for integration of the Attolight CL instrument<br />
in a larger spectroscopic system<br />
– Optional Time-Resolved Cathodoluminescence (TRCL)<br />
mode : optimized for pulse operations up to 10 ps without<br />
any degradation of the spatial resolution. Enables lifetime<br />
and charge carrier dynamics measurements
Applications<br />
– LED performance and reliability<br />
– GaN power transistors<br />
– Threading Dislocation Density (TDD)<br />
– Carriers lifetimes and dynamics<br />
– Solar cells efficiency<br />
– Development of nanoscale optolectronic devices<br />
ZnO nano-belts. The acquisition of a CL map (left) does not affect the detection<br />
of secondary electrons (right)<br />
Cathodoluminescence is the ideal tool to measure threading dislocations density<br />
in GaN (left) ; they appear as dark spots because of non radiative recombination<br />
in their vicinity. A secondary electron scan of the same region cannot identify any<br />
threading dislocations (right).<br />
Product Specifications<br />
Measurements Mode<br />
– Optical microscope imaging<br />
– Cathodoluminescence mapping (polychromatic,<br />
monochromatic and hyperspectral)<br />
– Secondary electrons (SE) mapping<br />
– Time-resolved cathodoluminescence (time-resolved option)<br />
– Simultaneous SE and CL imaging<br />
Electron Optics<br />
– Schottky field emission gun (continuous system) or<br />
picosecond pulsed photoelectron gun (time-resolved<br />
option). Acceleration voltage : 3–10 kV<br />
– Electron optical column with electro-magnetic lenses,<br />
magnetic deflectors and astigmatism correctors. Optimized<br />
for continuous and pulsed operation.<br />
– Highest spatial resolution : < 10 nm from 3 to 10 kV<br />
– Analytical working distance : 3 mm<br />
– No loss of SE resolution in cathodoluminescence mode<br />
– Field-upgradable to picosecond pulsed photoelectron gun<br />
Probe Current<br />
– E-beam : 1pA to 20 nA<br />
Light Optics<br />
– Light microscope embedded within the electron optics<br />
– Fully achromatic reflective objective : 180 nm – 1.6 µm<br />
– Aperture : NA 0.71 (f/0.5)<br />
– Field of View : >300 µm (electronic and optical)<br />
– Optical Resolution :
Be Part of the New<br />
Cathodoluminescence<br />
Revolution<br />
Nanopositioning Stage<br />
– Specimen diameter : ø 25x1.5 mm<br />
– 6 degrees of freedom for arbitrary movements (compatible<br />
with cryostat option)<br />
– Travel range : 25 mm (X and Y), 3 mm (Z), 3° tilt (X and Y),<br />
35° rotation (Z)<br />
– Smallest increment : 1nm<br />
– Repeatability (full travel range) : 100nm<br />
– Repeatability (100 nm range) : < 2nm<br />
Low Temperature Cryostat<br />
– Helium cold finger for low vibrations<br />
– Minimal temperature range : 20K–300K<br />
– Advanced digital temperature controller<br />
Facility Specifications<br />
– Power : 7 standard wall plugs (230V, 50Hz) delivering<br />
10A each<br />
– Pressurized air for microscope valves and optical table,<br />
pressure of 551 kPa (80psi) max.<br />
– Nitrogen to purge the chamber<br />
– Weight :<br />
CL system : 250 kg<br />
Optical Table : 650kg<br />
– Environment: temperature 20°C +/-3°C, relative humidity<br />
below 70 % RH, stray AV magnetic fields<br />
< 100 nT asynchronous<br />
< 300 nT synchronous for line times > 20 ms<br />
(50 Hz mains)<br />
260<br />
Lay-out<br />
The Attolight CL is mounted on an optical table with four<br />
active isolation legs. Its footprint is 1.2 m x 1.5 m. Allow for<br />
1 to 1.5m space around the table to circulate and install an<br />
operator.<br />
230<br />
wavelength (nm)<br />
200<br />
1514<br />
0<br />
200 400<br />
3200<br />
1209<br />
time (ps)<br />
1500<br />
Time and spectrum-resolved cathodoluminescence of Boron Nitride. The<br />
spectrum is generated by focusing a pulsed electron beam on a specific point of<br />
the specimen. A streak camera is used for the detection. Deep UV spectroscopy<br />
becomes as simple as visible spectroscopy.<br />
1000<br />
4000<br />
Attolight AG © 2012. We are constantly improving the performance of our products, so all specifications are subject to change without notice.
Be Part of the New<br />
Cathodoluminescence<br />
Revolution<br />
Attolight CL / Analytical Services : Get an immediate and easy<br />
access to critical data to boost your material research programs<br />
Attolight has developed breakthrough technology in cathodoluminescence which will open<br />
a new area of investigation in semiconductor material research. Attolight now offers immediate<br />
access to data that will significantly impact your processes, your technological research and<br />
development roadmap.<br />
Q. Why does Attolight, an equipment manufacturer, provide analytical and consulting services <br />
A. Typically in response to one of two situations :<br />
a → Our client needs to push forward their research or process development but<br />
has no budget to add capital equipment :<br />
– Your current characterization methods do not allow you to achieve a full understanding<br />
of your material system or structure, perhaps cathodoluminescence will<br />
fill in the gaps and allow you to reach clear conclusions.<br />
– You have come up against a specific process (or quality) issue and would like to see<br />
if cathodoluminescence could provide the information needed to solve the issue.<br />
– You already use photoluminescence technique but have found you need a higher<br />
spatial resolution or sensitivity to acquire the data you really need.<br />
b → Our client is making (or has made) a case for capital funding confident that<br />
high reso lution CL is a game changing technology for their research and process<br />
development.<br />
– You are confident, but your funding authorities still demand proof in the form<br />
of preliminary results showing the type of data that can not be obtained by other<br />
methods available to you.<br />
– You have a material/device with unique properties, you believe high resolution<br />
CL will provide the key data with which you can explain those properties in order<br />
to win funding for further development of your new material/device.<br />
– You have applied for funding but it will take many months to arrive, you need<br />
to push the research forward to maintain your lead until the Attolight system<br />
is delivered.<br />
Our laboratory in Switzerland provides analytical testing services and solutions, using the latest<br />
cathodoluminescence technology developed by Attolight. Our solutions enables the characterization<br />
of a variety of nano scale structures including : nanoparticles, nanotubes, quantum<br />
dots, defects, dopant inclusions, silicon wafer and ingot quality control for PV applications, GaN<br />
wafer quality control for LED and power devices. Attolight has also developed a proprietary<br />
solution to count the threading dislocation densities on wafers, offering a significant cost ownership<br />
benefit over the traditional TEM method.<br />
For more application on our analytical<br />
service capabilities please contact us :<br />
t + 41 21 626 0100
Headquarter – Attolight AG<br />
EPFL Innovation Square / PSE D<br />
1015 Lausanne / Switzerland<br />
t +41 21 626 0100<br />
contact@attolight.com<br />
www.attolight.com