IQE Scan

Spectral quantum efficiency and reflectance


  • Monochromatic light between 350-1200 nm from fully motorized grating monochromator and 250W tungsten lamp (optional 450W Xe lamp for wavelengths down to below 300 nm)
  • The homogeneous 20 mm x 20 mm light spot can be focussed to a minimum of approx. 1 mm x 3 mm by software
  • The illumination with white bias light up to 1.2 suns is restricted to the area of monochromatic illumination. The intensity is pc-controlled.
  • Bias light ramp for automatic determination of the bias light intensity for quasi-absolute QE measurements in only one wavelength scan. The procedure is also useful to check the linearity of the solar cell.
  • Very good signal-to-noise-ratio because of the local illumination with bias light
  • Fast local measurements (<1 sec. per wavelength)
  • Full-area measurements by moving the illuminated area continuously over the solar cell surface. With scanning speeds between 100 and 200 mm/s the measurement duration is comparable to the duration for setups with full area illumination.
  • Monitor detector to eliminate of lamp drifts
  • Temperature controlled vacuum chuck (see CELL Mount) mounted on servo-controlled x-y-z stage
  • An optional automatic calibration facilitates the work with the machine considerably. The calibration unit contains 3 calibration standards for EQE and reflectance, which will be measured automatically in advance if necessary.
  • Transimpedance amplifier (max. 200 mA) with 4-point contact scheme and pin-check. The QE is measured at short circuit (V = 0V).
  • Lock-In technique used for separating the current signal of the chopped monochromatic light and the bias light.
  • Integral spectral reflectance measured under 2 x 2 cm² light beam with a BaSO4 coated integrating sphere
  • Changing between QE and reflectance within seconds
  • Software with two operator levels for either easy use and or ample direct hardware access
  • The measured spectra are relative, i.e. a wavelength-independent scaling factor remains unknown. This scaling factor can be determined with a known short circuit current or the requirement, that the IQE is unity for short wavelengths when there are no emitter losses.