Photoluminescence (PL)

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Photoluminescence (PL)

• Process Design Lab
• ? ? ?

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Introduction

• Photoluminescence(PL)? ??
• PL Measurement
• Example

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Photoluminescence(PL)? ??
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What is Luminescence ?

• Luminescence (??)
• ?????? ??? ???? ? ?? ?? ??? ?? ????
  ??(transition)?
• ?? ??? ???? ? ??? ????? ??? ????? ????? ???
• ??? ??

? ??? ?? ??? ????? ??? ?? - ? ??
(photoluminescence) - ?? ??
(electroluminescence) - ??? ??
(cathodoluminescence) - ???? ?? (Bioluminesence)
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Photoluminescence ??

• ????? ?? ???
• Photon ??? ????
• ???? ???
• (e-h pair ??)

eh pair? ??? ?? ??? ???? ??? ??
??? ???? ?? Photon ???? ????
Photon(?)? ??? ??
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Photoluminescence? ??

• Photoluminescence
• 1) Band to Band Luminescence
• 2) Exciton Luminescence
• 3) Band to impurity Luminescence ( Free to
  Bound )
• 4) Donor Acceptor Pair Luminescence
• 1) Band to Band Luminescence
• - ???? electron? ????? hole? ???? ???
• - ???? ???? ??? ???? ????,
• ??? ?? ??(??)??? ????

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Photoluminescence? ??(2)
2) Exciton Luminescence a. Free exciton
- ???? ??? ????? ??? ?? ?????? ?? ??.
???? ?? ???? ???? ????. -
Exciton ??? ?? ??? hv
Eg-Ex (Ex exciton? binding Energy) b.
Bound Exciton - ????? free exciton?
impurity??? defect?? ???? ?? ?? - ?????
free electron? acceptor??? hole?? ??? (A,x)
- ???? hole? donor??? electron?? ??? (D,x)
- Peak? ???, ??, ??? ???? residual impurity?
dopant? ???? ? ?? ? ? ?? - Bound
Exciton ??? ?? ??? hv Eg
Ex Ebx (Ebx B.E.? Binding
Energy)
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Photoluminescence? ??(3)
4) Donor Acceptor Pair Luminescence -
electron? ???? ????? ???? ?? donor? hole? ????
????? ???? ?? acceptor?? radiative ???? ??
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PL Measurement
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PL Measurement (1)

???? 
??? ??

• 1. Laser? ??? ?? laser ??
• (? 30?? warm up).
• 2. ?? optics (mirror, copper)? ??
• 3. ?? ??? ??? spectrometer calibration
• 4. Sample ??
• 5. Spectrum? ??

• ??? ???? ???? ???? ??
• ??? ?? ???.
• - ?? ?? 1? ??
• - ?? ?? ?? ?? spot?? ??

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PL Measurement (2)
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PL Measurement (3)

• Light source Band gap ??? ???? ?? ? ??
• He-Ne ???(red,632.8nm), Ar ???(blue,
  488nm), He-Cd ???(uv, 325nm)
• Chopper ? ??? ??
• Filter ???? ? ?? ??? ???, ?? ??? ??????
• ??? ?? (????, ???????,.)
• Cryostat ?? ?? ??
• Monochromator ??? ??
• Detector
• Lock-in amplifier Low frequency noise ? ????? ??

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PL Measurement ??

• ? ?
• ?? ????
• ? ?? ?? (non-destructive analysis)
• Beam alignment, surface flatness, sample
  thickness? ??? ?? ??.
• ? ?
• ???, ??? ?? ?? ??? ??? ???.
• ?? ??? ??? ???.

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Example
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Example (1) band gap energy ??

• E hv
• hc/??
• (6.63   10-34 Js)(3108 m/sec)
• 360.3 nm
• 5.52 10-19 J
• 3.44 eV
• (1 eV. 1.601 x 10-19 J)
• GaN band gap energy
• 3.39eV

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Example (2) - ?? ??

• PL spectra of three epitaxial Si samples,
  Thewalt et al.

Equip. PLSRA (spreading resistance analysis
depth profiling) (ac) epitaxial Si sample (d)
substrate material
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Example (3)- defects ??
Photoluminescence characterization of the surface
layer of chemically etched CdTe J.
Garcia-Garcia et al. (1989) The effects of
several reducing and oxidizing etches on CdTe
surfaces have been characterized by
photoluminescence. For excitation, several lines
from three different types of gas lasers,
emitting at 325nm(He-Cd laser), 488nm
(argon-ion laser), and 632.8m,(He-Ne laser) were
used.
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Example(4) Image mapping
Mapping of the area of the PL peak
InGaN MQW/GaN/ Sapphire base 2 inch wafer
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Example (5)
???? ??? ??? '??' ??? ???? ???? ??? 705? ? ??

• - ? ????? ????? ????? ?? ???(???30)?? ??.
• - ??? ??? ??? ??? ?? ??? ???(???
  Photoluminescence) ??. ?? ??? ??? ???? ?? ??
  ??? ??. ??? ?? ??? ?? ??? ????? ???, ?? ??? ????
  ?? ??? ??? ??.
• (???? 2004.11.28)