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An aluminium nitride light-emitting diode with a wavelength of 210 nanometres

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Abstract

Compact high-efficiency ultraviolet solid-state light sources1—such as light-emitting diodes (LEDs) and laser diodes—are of considerable technological interest as alternatives to large, toxic, low-efficiency gas lasers and mercury lamps. Microelectronic fabrication technologies and the environmental sciences both require light sources with shorter emission wavelengths: the former for improved resolution in photolithography and the latter for sensors that can detect minute hazardous particles. In addition, ultraviolet solid-state light sources are also attracting attention for potential applications in high-density optical data storage, biomedical research, water and air purification, and sterilization. Wide-bandgap materials, such as diamond2 and III–V nitride semiconductors (GaN, AlGaN and AlN; refs 3–10), are potential materials for ultraviolet LEDs and laser diodes, but suffer from difficulties in controlling electrical conduction. Here we report the successful control of both n-type and p-type doping in aluminium nitride (AlN), which has a very wide direct bandgap11 of 6 eV. This doping strategy allows us to develop an AlN PIN (p-type/intrinsic/n-type) homojunction LED with an emission wavelength of 210 nm, which is the shortest reported to date for any kind of LED. The emission is attributed to an exciton transition, and represents an important step towards achieving exciton-related light-emitting devices as well as replacing gas light sources with solid-state light sources.

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Figure 1: Electrical characteristics of n-type Si-doped AlN.
Figure 2: Electrical characteristics of p-type Mg-doped AlN.
Figure 3: AlN LEDs.

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Acknowledgements

We thank M. Prinz, K. Thonke and R. Sauer at the University of Ulm in Germany for measurement of free-exciton energy in our AlN by cathodoluminescence and photoreflectance. We are also grateful to K. Kumakura for discussions, and K. Torimitsu and H. Takayanagi for their encouragement. Author Contributions Y.T. performed experimental work and data analysis. All authors discussed results.

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  1. NTT Basic Research Laboratories, NTT Corporation, Atsugi, 3-1 Morinosato-Wakamiya, 243-0198, Japan

    Yoshitaka Taniyasu, Makoto Kasu & Toshiki Makimoto

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  1. Yoshitaka Taniyasu
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  2. Makoto Kasu
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Correspondence to Yoshitaka Taniyasu.

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Taniyasu, Y., Kasu, M. & Makimoto, T. An aluminium nitride light-emitting diode with a wavelength of 210 nanometres. Nature 441, 325–328 (2006). https://doi.org/10.1038/nature04760

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