A PEEK ON the lab

The Electron Physics Group, led by Professor Hele Savin, develops photovoltaic devices, such as solar cells, with silicon nanowires as the light-absorbing surface.

The nanowire surface appears black to the eye – this means that most of the visible spectrum of light is absorbed to the cell, unlike in conventional solar cells.

For further information about their research, check out https://www.aalto.fi/en/department-of-electronics-and-nanoengineering/electron-physics.

A fast and efficient way to characterize silicon wafers and ready-made devices is photoluminescence (PL) imaging.

Here is an example of a PL image of multicrystalline silicon wafer showing high spatial resolution revealing various defect types within the grains.

The sample is illuminated with a high-intensity laser, which in turn leads to emission of luminescent light on a certain wavelength range. The higher the intensity of the emitted light, the higher the potential efficiency of the device.

The Electron Physics Group explores the use of photoluminescence imaging in the characterization of silicon nanowire samples, photodetectors, and solar cells.

In this image, our researcher is preparing to characterize the conversion efficiency of a crystalline silicon solar cell.

The Electron Physics Group at Aalto University works at OtaNano Micronova, the national research infrastructure for micro- and nanotechnology. The group uses the cleanroom and laboratory facilities to fabricate and characterize semiconductor materials for high-efficiency photovoltaics. Characterization includes, for example, determining the average lifetime of light-generated charge carriers using photoconductance measurements, mapping nanowire morphologies with scanning electron microscopy, and photoluminescence (PL) imaging of solar cells.