Optical characterization of semiconductor materials and heterostructures from UV to IR

Head of the laboratory: Prof. Pikhtin A.N.

Modern photonics and optoelectronics have been some of the most rapidly developing areas of science in the recent decades. Optoelectronic components, which include such devices as semiconductor lasers, light-emitting diodes (LEDs), photodetectors and solar cells, are being produced in increasing volumes. Their fields of application include fiber optic communication systems, optical disc recording and reading technologies, along with various areas of medicine, ecology, and industry. Light-emitting diodes are also becoming increasingly popular as highly energy-efficient, safe and environmentally friendly sources of visible light.

Experimental techniques

  • Optical transmission, reflection and absorption spectra measurements in a broad spectral range (from UV through Visible to MIR)
  • Photoluminescence and electroluminescence measurements
  • Advanced spectroscopy methods - modulation spectroscopy: photomodulated and electromodulated reflection and transmission measurements
  • Nondestructive characterization of LEDs
  • Fourier-transform infrared spectroscopy (FTIR): a highly efficient technique that allows for fast acquisition of high-resolution, low-noise infrared spectra.

Examples of research

  • Photoreflectance and electroreflectance studies of ultrapure GaAs, InGaAs/GaAs quantum wells and “quantum rings”
  • IR photoluminescence studies of InSb/InAs quantum dot structures
  • Optical characterization of band structure for narrow-gap AlInSb alloys

The Laboratory’s equipment includes

Vertex 80 Fourier-transform infrared spectrometer (Bruker Optics, Germany)

Features:

  • Broad spectra registration range from visible to MIR: 0.4 – 28 um, i.e. 0.045-3.1 eV.
  • Excellent spectral resolution: up to 0.2 cm-1
  • High light throughput
  • Fast measurement speed
  • Transmission and reflection spectra registration
  • IR luminescence measurements

Grating spectrometers for UV, visible, and NIR spectral range

Applications:

  • Visible and NIR luminescence measurements
  • LED emission measurements
  • Modulation spectroscopy



Cryostat: Janis CCR-150 closed-cycle helium refrigerator

Features:

  • Achievable temperature range: 9-325K.
  • Optical windows for UV, visible and IR: Quartz, CaF2 (calcium fluoride), ZnSe (zinc selenide).
  • Electrical connections are available.

 

SR-810 and SR-830 digital lock-in amplifiers

Employment of phase-sensitive detection allows for high signal-to-noise ratio registration of weak signals, such as IR photoluminescence and photomodulated reflection, while neglecting the effects of background light (such as 300K thermal radiation).