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Why DPSS Lasers are ideal for Photoluminescence applications

Skylark Senior Engineer Toby Jeffreys discusses Photoluminescence Spectroscopy and reveals how our lasers can provide a competitive edge for applications such as photoluminescent mapping.

At Skylark, we specialise in the development of single frequency lasers. More specifically, high power, single frequency UV lasers.

Our patented laser architecture allows us to provide unrivalled laser performance and this helps develop the next generation of photoluminescent mapping and Raman spectroscopy devices.

One of the main use cases of photoluminescence is defect detection of semiconductor wafers.

Spectral Purity = No optical filtering

The wavelength of our 320 and 349 nm lasers are well suited for inspection of gallium nitrate, silicon carbide and zinc oxide due to their discrete band gap energies.

Because of our lasers’ high spectral purity, they don’t require any optical filtering. However, if you use a gas laser there are a multitude of laser-related artefacts, such as plasma lines.

Therefore, you require optical filtering which then further reduces your optical power at the wafer.

Scan an 8-inch wafer in less than 1½ minutes

Photoluminescent mapping is a technique where a semiconductor wafer undergoes a raster scan across the full area of the wafer. Each scan requires a small area of the wafer to be illuminated by the UV light. The emission spectrum is then measured and a 2D colour map is generated, displaying either surface irregularities or band gap defects, depending on how the spectrum data is collected and analysed.

Our unrivalled UV power, coupled with the latest generation of spectrograph sensors and kinematic inspection stages, allow for scan speeds of up to 250 per minute, enabling an 8-inch wafer to be scanned in less than 1½ minutes. This would provide a competitive edge for any photoluminescent mapping device.

"Scan speeds of up to 250 per minute allow an 8-inch wafer to be scanned in less than 1½ minutes"

Excellent power stability

In addition to our lasers’ high power and long lifetime, they offer other key parameters beneficial to photoluminescent mapping.

As you can see from these plots, we achieve a very good power stability of 1% over a 25-hour period. This is important for ensuring accurate quantum defect measurements.

Wavelength stability

In addition, we see wavelength stability of less than 0.1 picometre over a 25-hour period. This is important to mitigate inaccuracies in excitation wavelengths.

Finally, the spatial mode properties are important to allow for effective re-imaging in the beam shape delivery, such as efficient fibre-coupling and top-hat beam shaping.

Want to learn how we can tailor a solution for you?

We offer UV lasers in various form factors to meet different customers’ OEM needs. Feel free to reach out to us at for your specific requirements. You can read more about photoluminescence spectroscopy here, or request a quote here.

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