Low frequency noise measurements under illumination for defect characterization in photovoltaic cells

Low frequency noise measurements under illumination
for defect characterization in photovoltaic cells

Photovoltaic technologies are among the least carbon-intensive sources of energy and are therefore a fundamental research area in the current context of energy transition. Increasing the performance of these devices and their operating lifetime is one of the main challenges in this field.
At the center of this dual challenge is the problem of defects in solar cells. Indeed, the presence of defects in the volume or at the interfaces of the junction, encouraging the recombination processes of the photo-generated carriers, strongly decreases the lifetimes of the latter, and so the efficiencies of photovoltaic cells. On the other hand, the progressive formation of these defects during the operation of the cell leads to a malfunction of the device. It is therefore compulsory to limit the presence of defects and their formation. However, before limiting them, it is necessary to be able to measure, identify and quantify them.

In this context, research is developed at IMEP-LaHC on the use of low frequency noise, a method used for several decades in the MOSFET transistor to extract defects densities at the interface between the conduction channel and the grid oxide in particular. The objective of this research is to apply this characterization method to photovoltaic cells.
A first PhD currently in progress has already demonstrated that this method is applicable to these components, and that it is a source of information on the nature of electronic transport mechanisms not accessible by conventional methods.
The objective of this internship is to go further on the use of low frequency noise, by exploiting the optical generation in the device during the measurement. Some experimental results recently published suggest that it is possible to optically and selectively stimulate certain defects at different energies, and to measure low frequency noise responses reflecting different signatures depending on the wavelength band used. Although promising, these published results are very partial and require a more detailed exploration of the potential of this electro-optical method.
The work required in this internship is therefore mainly experimental, focused on the measurement of low frequency noise, and instrumental, as it will be necessary to modify the current measurement bench to add light sources. Some manipulations in clean room to make samples are possible depending on the skills and interests of the candidate.

Contacts : Chloé Wulles : chloe.wulles@grenoble-inp.fr
Quentin Rafhay : quentin.rafhay@grenoble-inp.fr
Christoforos Theodorou : christoforos.theodorou@grenoble-inp.fr
Anne Kaminski : anne.kaminski@grenoble-inp.fr

Institute of Microelectronics, Electromagnetism and Photonics-Laboratory of Microwave and Characterization
Joint Research Unit 5130 CNRS, Grenoble INP, UGA, USMB

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