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SF1 4 chip TXSilanna UV, based in Queensland, Australia, is a leading developer and manufacturer of advanced ultra-violet (UV) LED technologies.

 

A range of UVC LEDs are offered at 235nm and 255nm with a choice of surface mount and TO-style packages.

 Constant Current Driver

Evaluation options include surface mount and TO devices pre-mounted on industry-standard "star pad" boards as well as a larger 55 x 55mm² "extended evaluation board".

 

The constant current LED driver board provides protection for the LEDs with user-selectable drive currents of 20mA or 40mA and dimming via Pulse Width Modulation (PWM). 

 

Silanna UV's technology is differentiated from other manufacturers due to their use of short period superlattice (SPSL) or "digital alloy". This can essentially be considered a new material system that is much easier to tune, with properties that are far superior to traditional doped AlGaN crystal lattice.

 

Where Silanna UV's competitors control the wavelength of their devices by fine-tuning ratio of Al and Ga in their AlxGa1-xN growth, Silanna UV's AIN/GaN SPSL digital alloy structure is precisely controlled by changing the layer thickness:-  

 

Bulk crystal lattice vs SPSL

 

The use of SPSL digital alloy technology allows Silanna UV LEDs to stand out from their competitors, providing the following advantages:


Ability to easily tune wavelengths: Where bulk AlGaN is prone to segregation and requires the tuning of Al to Ga species ratio which can be hard to control, binary SPSL is less prone to segregation and wavelength tuning only requires the simple change in deposition time to control the thickness of the layers. Silanna UV have demonstrated devices operating at 227nm.

 

Maintains high power at lower wavelengths: Traditional AlGaN technology suffers from vertical light extraction issues at short wavelengths due to the transition of emission from vertical (TE) to lateral (TM) in high Al content AlGaN. Only a small amount of the generated photons are emitted vertically in these traditional structures - resulting in low efficiency. However, since the emission from an SPSL is governed by thickness and period rather than composition, the emissions originating from the GaN part of the SPSL remain mostly vertical through the whole spectrum, allowing high power to be maintained even at ultra-short wavelengths.

 

Superior Electrical Characteristics: Because the emission wavelength of SPSL based digital alloy LEDs is tuned via thickness rather than the actual bandgap of the material, a higher conductivity can be maintained. In n-doped bulk AlGaN, reducing the wavelength requires a wider bandgap which means increasingly deep donors, whereas in SPSL the donors remain shallow regardless of wavelength. This allows a low drive voltage and high efficiency to be maintained even at the lowest emission wavelengths.

 

Silanna UV's SPSL digital alloy technology is discussed in more detail in our support page Silanna UV SPSL Technology.

 

Silanna UV use their SPSL digital alloy technology through the entire device stack, taking full advantage of the superior properties described above. Using this approach, they have successfully demonstrated high performance Deep UVC and Far UVC LEDs down to 227nm. Of these, LEDs covering the 235nm and 255nm range are already in production. Products in other wavelength ranges are expected to be available in the near future.

 

For more information on Silanna UV's 235nm and 255nm LEDs please visit the UVC LED page or contact APT to discuss your application.