Photoluminescence (PL)

Photoluminescence spectroscopy is a contactless and non-destructive method to probe the electronic structure of materials

Photoluminescence is based on the emission of light upon light excitation. An incident light is absorbed and photo carriers are generated. Following excitation various relaxation processes typically occur in which other photons are re-radiated.

The intensity and spectral content of the emitted photoluminescence is a direct measure of important material properties, including:

  • Band Gap Determination
  • Impurity Levels and Defect Detection
  • Recombination Mechanisms
  • Material Quality
  • Molecular structure and crystallinity

Keywords
Laser, light emission, electron-hole recombination, radiative recombination.


Specifications

The micro-photoluminescence equipment is a Horiba LabRAM HR system equipped with
  • Multiple laser sources: 325, 405, 488, 514 and 633 nm with optical densities to adjust the power
  • Mapping stage 100×100 mm with 100nm resolution
  • Removable Helium cryostat (sample holder ∅ = 20mm, minimum temperature = 5K)
Detectors spectral range: ∼300-1600nm
  • UV-visible CCD
  • NIR InGaAs photodiode array
Spectrometer and gratings (groves.mm-1@blaze)
  • 100@450nm, 600@500nm, 1200@500nm
  • 150@1200nm, 600@1000nm
  • 800mm focal length
Confocal microscope with different objectives
  • Short working distance: 40× NUV, 50×, 100×, 100× NIR
  • Long working distance when using the cryostat: 10×, 50×, 100×, 15× NUV, 50× NIR

Ascent+ facility
CEA-Leti

Platform Technologies

  • Nano for Quantum Technologies
  • Disruptive Devices
  • Advanced Integration

Key Enabling Technologies

  • Metrology / Characterisation: Optical and Physical

Case Study

Users are trying to measure the emission spectrum of their sample to characterize the material or device properties.
They first define which laser is suitable for their sample (e.g. which incident energy is high enough to excite the sample). The expected emission bands should have to be inside the detection range of the equipment. The sample size would have to be compatible with the cryostat if needed.

Typical Applications
Such characterization is essential in the case of 2D materials, light emitting diodes, solar cells and other optoelectronic devices

Publications
[DOI: 10.1063/1.4993741]
[DOI: 10.17586/2220-8054-2019-10-3-361-373]
[DOI: 10.1088/1361-6528/ab80fe]

Key Enabling Capability

Metrology / Characterisation

Platform Technology

Advanced Integration, Disruptive Devices, Nano for Quantum Technologies

Facility

CEA-Leti