UV Light Emitting Diodes (UV-LEDs)

We develop (In)AlGaN-based light-emitting diodes (LEDs) with emission in the ultraviolet (UV) spectral region. The research work takes place in close cooperation with the TU Berlin within the Joint Lab GaN Optoelectronics. Activities include device simulation, design, epitaxy of (InAlGa)N heterostructures, device chip fabrication, assembly and characterization.

Advantages of our UV-LEDs at a glance

emission wavelength can be adjusted to the respective application by adapting the heterostructure
small, compact and robust
can be operated at low voltages (mobile applications)
can be switched quickly
do not contain toxic substances

Thanks to these properties, UV LEDs are already superior to conventional UV emitters such as mercury-based gas discharge lamps in many respects. As technology advances, the advantages of UV LEDs will continue to increase.

Processed wafer with UV-LEDs, which is held by tweezers — Processed LED wafer

On-wafer measurement of a UVB LED wafer with an LED that emits light — On-wafer measurement of a UVB LED wafer

Single LED chips that are positioned on a gel pack — LED chips in gel pack

UV LED in an aluminum nitride SMD package

Current research focus:

300-320 nm for surface polymerization, phototherapy and plant irradiation, typ. light output power 25 mW (350 mA)
230-235 nm for skin tolerant UV antiseptics, typ. light output power 6 mW (200 mA)
225-230 nm for gas sensing, typ. light output power 0.25 mW (200 mA)

Previous wavelength ranges:

260-280 nm for water, air and surface disinfection, typ. light output power 18 mW (350 mA)
250-260 nm for spectroscopy, typ. light output power 9 mW (350 mA)

Our best UV LEDs achieve up to twice the light output power as specified above. Together with our in-house Prototype Engineering Lab, we assemble our UV LEDs into lamp modules and complete irradiation systems. We test these with partners in practical applications such as plant irradiation or wound and skin disinfection.

simulation of the LED heterostructure
epitaxial deposition of the (InAlGa)N heterostructures on different MOVPE machines
chip technology in the process line of the FBH clean room (including monolithically integrated gold micro-stud-bumps for subsequent flip-chip assembly via thermocompression)
assembly of LED chips in SMD packages made of AlN ceramics or crystalline silicon, which can be sealed with lens covers
characterization (including measurement of the power-current-voltage characteristics as well as their spectra on-wafer or on the mounted chip, detailed aging studies to analyse possible degradation mechanisms)

The full UV LED value chain – a look behind the scenes at FBH's laboratories and manufacturing steps

Multi-λ UV-LED module

Selected Publications

Origin of the parasitic luminescence of 235 nm UVC LEDs grown on different AlN templates

Appl. Phys. Lett., vol. 124, no. 6, pp. 063506, doi:10.1063/5.0183772 (2024).

Enhanced light extraction efficiency of far-ultraviolet-C LEDs by micro-LED array design

Appl. Phys. Lett., vol. 122, no. 26, pp. 263508, doi:10.1063/5.0154031 (2023).

234 nm far-ultraviolet-C light-emitting diodes with polarization-doped hole injection layer

Appl. Phys. Lett., vol. 122, no. 19, pp. 191101, doi:10.1063/5.0143661 (2023).

Spatially resolved degradation effects in UVB LEDs stressed by constant current operation

Appl. Phys. Lett., vol. 122, no. 13, pp. 131103, doi:10.1063/5.0141530 (2023).

Strain induced power enhancement of far-UVC LEDs on high temperature annealed AlN templates

Appl. Phys. Lett., vol. 122, no. 01, pp. 011102, doi:10.1063/5.0134253 (2023).

Spectrally pure far-UVC emission from AlGaN-based LEDs with dielectric band pass filters

J. Phys. D: Appl. Phys., vol. 55, no. 20, pp. 205105, doi:10.1088/1361-6463/ac5145 (2022).

Impact of operation parameters on the degradation of 233 nm AlGaN-based far-UVC LEDs

J. Appl. Phys., vol. 131, no. 01, pp. 014501, doi:10.1063/5.0069590 (2022).