Time-resolved cathodoluminescence is a technique in which the time dynamics of the cathodoluminescence emission process is observed. This presentation will give you an overview of the time-resolved cathodoluminescence techniques: lifetime imaging (or emission decay) and g(2) imaging, which is also known in physics as second-order correlation function. The SPARC is a high-performance cathodoluminescence detection system designed and produced by Delmic, which offers a unique solution for cathodoluminescence imaging. With the Delmic LAB Cube (a time-resolved CL module) for the SPARC, it is possible to extend the SPARC to do lifetime and antibunching experiments. For questions about cathodoluminescence, the SPARC and the LAB Cube, please leave a comment below or visit www.delmic.com and send us an email.

1. Integration without compromise
Time-resolved сathodoluminescence

2. What is time-resolved cathodoluminescence?
• Time-resolved cathodoluminescence is a technique in which
the time dynamics of the cathodoluminescence emission
process is observed
• Main imaging techniques:
1. Lifetime imaging
2. g(2) imaging

3. How does cathodoluminescence work?
When a sample is bombarded by fast electrons,
the material becomes excited as it returns to a
grounded state, it emits light.
The radiation that is generated in the
ultraviolet/visible/near-infrared regime of the
electromagnetic spectrum is referred to as
cathodoluminescence (CL) as the radiation is
generated by cathode rays (fast electrons).
This data can be collected with nanoscale
resolution and can reveal contrasts that cannot
be observed with any optical microscopy
technique.

4. Lifetime cathodoluminescence imaging
• Lifetime (or decay trace) mapping is one of the time-resolved techniques
• The method can be used to obtain insight into a large variety of physical
processes and material properties
• To perform lifetime cathodoluminescence imaging, a pulsed electron
microscope is required
Lifetime Imaging Mod
e

5. Spontaneous light emission process in time
Lifetime Imaging Mod
e

6. To study lifetime imaging,
a fast photodetector such
as an avalanche
photodiode (APD) or
photomultiplier tube (PMT)
can be used to detect
single photons with high
sensitivity and timing-
precision
Detection
Lifetime Imaging Mod
e

7. Application of lifetime imaging technique
CL decay-trace measurements can be used for a large range of applications
The extracted lifetime measurements are valuable to obtain information on
intrinsic material properties as well as the local optical environment
Obtaining time dynamics of the material can be very useful for studying
semiconductor materials used for optoelectronic devices or rare-earth doped
materials
Lifetime Imaging Mod
e

8. Application of lifetime imaging technique
Lifetime Imaging Mod
e

9. Cathodoluminescence g(2) imaging
• The g(2) function is a useful tool to study cathodoluminescence emission
from a (nano)material
• In a beam of light, the distribution of photons can be described by the
normalized second order autocorrelation function g (2) (𝜏)
g(2) Imaging Mode

10. Antibunching in cathodoluminescence
A single-photon emitter can only emit one photon at a time and therefore it is impossible t
o observe coincident photons.
When the g(2) function drops below 1 with g(2)(0)= 0, it is referred to as antibunching.
The antibunching effect can be used to identify and characterize quantum sources
of light.
Figure 4: Characteristic g(2) curves for
different cases. The red balls represent a
schematic photon distribution in time for
particular g(2) curves.
g(2) Imaging Mode

11. g(2) detector
• The most common approach to measure the g(2)(𝜏) is in a Hanbury Brown and Twiss (HBT)
interferometer consisting of a 50/50 beam splitter with two ultrafast single-photon detectors
(SPDs)
• These SPDs generate a single electrical TTL or NIM pulse for every detected photon, which is then registere
d and timed by time-correlator electronics in a time-correlated single-photon scheme (TCSPC)
• The time-resolved module LAB Cube can coupled to the SPARC CL system with fiber coupler
Figure 5: Schematic overview of the DELMIC L
AB Cube system, that can be used for g(2) acqui
sition.
Bunching g(2) curve courtesy of Dr. Sophie Meur
et
(AMOLF, Amsterdam)
g(2) Imaging Mode

12. Applications of cathodoluminescence g(2) imaging
• g(2) imaging can be used to identify and characterize single-photon emitter at the nanoscale
• The method can be used in fundamental studies on quantum systems and their interaction with
electron beams
• The bunching effect is useful for studying bulk and mesoscopic materials systems including
optoelectronic devices (such as LEDs and solar cells)
Figure 6: Example of g(2) mapping data on InGaN/GaN
nanorods shown in the SEM image (a). (b) The g(2) data
recorded at three colored squares as indicated by the arro
ws in panel (c) which shows SE intensity recorded togethe
r with
the g(2) data set. Maps of (d) lifetime τe, (e) amplitude g(2) (
0)-1 and (f) the probability of excitation γ are also shown. I
f the
data was too noisy to extract these parameters, the pixel
was left white in the map. The contours of the nanorods ar
e
indicated by the black lines.
Figure courtesy of Dr. Sophie Meuret (AMOLF, Amsterdam
) g(2) Imaging Mode

13. Cathodoluminescence detector SPARC
The SPARC platform
+ High-performance
cathodoluminescence detection system
+ Modular design allows for addition of
different detectors and detection paths
+ High-precision alignment stage gives
unprecedented photon yield and
reliability
+ Time-resolved mode makes new types
of research possible

14. Time-resolved SPARC module the LAB Cube
The LAB Cube
+ Lifetime imaging and antibunching
module for SPARC
+ Gives insight into intrinsic material
properties
+ Intuitive and easy to use software
integration with remote control
capabilities
+ Overnight acquisitions for more
accurate measurements
+ The LAB Cube is coupled to the SPARC
with an optical fiber, using the Fiber
Coupler Module

15. DELMIC B.V.
Address: Kanaalweg 4, 2628 EB,
Delft, The Netherlands
Website: www.delmic.com
Telephone: +31 (0)15 744 01 58
Email: info@delmic.com
Please visit Delmic’s website to learn more about time-
resolved cathodoluminescence