Berlin 2024 – scientific programme

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HL: Fachverband Halbleiterphysik

HL 52: Nitrides: Devices

HL 52.1: Talk

Friday, March 22, 2024, 09:30–09:45, EW 015

Heterostructure optimization of far-ultraviolet C light emitting diodes for improved efficiency and lifetime — •Tim Kolbe, Sylvia Hagedorn, Jens Rass, Hyun Kyong Cho, Jan Ruschel, Sven Einfeldt, and Markus Weyers — Ferdinand-Braun-Institut (FBH), Gustav-Kirchhoff-Str. 4, 12489 Berlin, Germany

The development of AlGaN-based light emitting diodes (LEDs) with emission wavelength in the far-ultraviolet-C (far-UVC) spectral region (< 240 nm) is driven by various applications like monitoring of gas concentrations (e.g. NO, NH3), the measurement of nitrates in water, or skin-friendly UVC-antisepsis. Although these LEDs have been improved over the recent years, the maximum emission power of the devices and their lifetimes are still low compared to UV LEDs in the longer wavelength range. In this presentation, an overview of our far-UVC LED development will be given. The influence of the heterostructure design and optimization of the epitaxial growth processes on voltage, emission power, and reliability of far-UVC LEDs will be discussed. Among other things, it will be shown how the design of the active region (e.g. quantum well numbers and quantum well barrier height) influences the voltage, optical power, and lifetime of the LEDs. Based on these optimizations, 233 nm LEDs with a maximum peak external quantum efficiency (EQE) of 1.13 % (wall plug efficiency of 0.82 %), an emission power of 9.7 mW and an operation voltage of 7.9 V at 200 mA were realized.

Keywords: far-UVC; LED; MOVPE; ultraviolet; heterostructure