Can someone please help me compare PL and CL in terms of :-
a) thermalization process
b) energy level population
c) energy transfer to the lattice
d) phonon emission
e) temperature of excess carriers
f) line width broadening
g) e-h pair density
h) dependence on scan rate
i) increase in specimen temperature
Also, please suggest the available literature on the same. Thank you in anticipation.
Hello Aman,
the essential difference between PL and CL consists in the excitation process:
- the excitation energy of PL amounts some eV, the momentum is very low and is comparable to the photon momentum hk.
- the excitation energy in CL is very high (some keV). The momentum compares with the electron momentum.
- In PL you must take into account strong selection rules for momentum, energy and angular momentum. Therefore, in PL dominate direct transitions from valence band to the band of conductivity. Indirect transitions require the interaction with phonons and depend strongly from temperature.
In CL you excite the whole spectrum of possible transitions - from X-ray to thermal excitations. "Optical" excitations are thermalized electrons which occupy all empty bands.
- Whereas you can in PL selectively occupy bands, the bands in CL are occupied statistically.
With Regard
R. Mitdank
Rüdiger Mitdank sir thanks for the prompt reply. I am sure with your vast experience in the field and the expertise, you can provide further details on the topic. Suggesting some good reference will also add to the inputs.
Point wise comparison between PL and CL, shall simplify the things. From your answer I note that:
1. Excitation energy: ~ eV in PL / ~ keV in CL
2.
Help me compile the above comparison points.
Thanks and regards
Aman Arora
1. CL has high spatial resolution (values? for PL and CL)
2. CL has ability to obtain depth-resolved information by varying electron-beam energy
3. Excitation energy: ~ eV in PL / ~ keV in CL
4. In PL, a photon generates only one e-h pair, whereas in CL, on 20 keV electron can generate thousands of e-h pairs
Dear Aman Arora
The Cathodoluminescence emission could be caused by the presence of hydrogen atoms in the oxide phase, which is decreased by electron beam irradiation, but the Photoluminescence emission could be caused by defects in the dioxide on the porous silicon surface, as shown by scanning electron microscopy photographs.
https://www.sciencedirect.com/science/article/abs/pii/S0038109807004073#:~:text=The%20Cathodoluminescence%20emission%20may%20originate,by%20scanning%20electron%20microscopy%20images%2C
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