When applying a forward biased voltage to a photovoltaic device or illuminating it with light, a weak amount of light can be detected, which originates from light emitted by minority carrier recombination. The amount of the light can be quantitatively analyzed to characterize carrier lifetime and sheet resistance. The spatial distribution indicates defects (such as micro-cracks), material inhomogeinities, delaminations and many other phenomena which are all relevant for the quality of photovoltaic detectors. The recombination radiation is typically centered in the near infrared wavelength region. In case of silicon materials it is centered at 1100 nm.

When applying a reversed bias voltage to a photovoltaic device, weak light signals can be detetected even below its break down voltage level caused by defects (e.g. shunts) of a solar device.

 

When light is shining on a semiconductor (excitation),  a photoluminescence signal is generated (emission). By spectrally separating the excitation and emission signal and imaging the luminescence signal by a sensitive camera, characterisation and defect analysis of raw bulk material, wafers in process, finished cells is possible.

Cell efficiency, material properties, process failures or cracks can be analyzed.

 

For these applications highly sensitive cameras are required. In order to meet the varying demands of cell and panel inspection in quality assurance as well as in basic research, a broad line of products is offered. All cameras are optimized towards high sensitivity in the near infrared range.