Proposing the n⁺-AlGaN tunnel junction for an efficient deep-ultraviolet light-emitting diode at 254  nm emission

Abstract

Toxic and low-pressure deep-ultraviolet (DUV) mercury lamps have been used widely for applications of surface disinfection and water sterilization. The exposure of pathogens to 254 nm DUV radiations has been proven to be an effective and environmentally safe way to inactivate germs as well as viruses in short time. To replace toxic mercury DUV lamps, an <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"> <mml:mrow class="MJX-TeXAtom-ORD"> <mml:msup> <mml:mrow class="MJX-TeXAtom-ORD"> <mml:mrow class="MJX-TeXAtom-ORD"> <mml:mi mathvariant="normal">n</mml:mi> </mml:mrow> </mml:mrow> <mml:mo>+</mml:mo> </mml:msup> </mml:mrow> <mml:mtext>-</mml:mtext> <mml:mrow class="MJX-TeXAtom-ORD"> <mml:mi mathvariant="normal">A</mml:mi> <mml:mi mathvariant="normal">l</mml:mi> <mml:mi mathvariant="normal">G</mml:mi> <mml:mi mathvariant="normal">a</mml:mi> <mml:mi mathvariant="normal">N</mml:mi> </mml:mrow> </mml:math> tunnel junction (TJ)-based DUV light-emitting diode (LED) at 254 nm emission has been investigated. The studied conventional LED device has maximum internal quantum efficiency (IQE) of 50% with an efficiency droop of 18% at <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"> <mml:mrow class="MJX-TeXAtom-ORD"> <mml:mrow class="MJX-TeXAtom-ORD"> <mml:mn>200</mml:mn> </mml:mrow> </mml:mrow> <mml:mspace width="thickmathspace"/> <mml:mrow class="MJX-TeXAtom-ORD"> <mml:mrow class="MJX-TeXAtom-ORD"> <mml:mi mathvariant="normal">A</mml:mi> <mml:mrow class="MJX-TeXAtom-ORD"> <mml:mo>/</mml:mo> </mml:mrow> <mml:mi mathvariant="normal">c</mml:mi> </mml:mrow> </mml:mrow> <mml:mrow class="MJX-TeXAtom-ORD"> <mml:msup> <mml:mrow class="MJX-TeXAtom-ORD"> <mml:mrow class="MJX-TeXAtom-ORD"> <mml:mi mathvariant="normal">m</mml:mi> </mml:mrow> </mml:mrow> <mml:mn>2</mml:mn> </mml:msup> </mml:mrow> </mml:math> . In contrast, the calculated results show that a maximum IQE of 82% with a 3% efficiency droop under a relatively higher injection current was estimated by employing a 5 nm thin <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"> <mml:mrow class="MJX-TeXAtom-ORD"> <mml:msup> <mml:mrow class="MJX-TeXAtom-ORD"> <mml:mrow class="MJX-TeXAtom-ORD"> <mml:mi mathvariant="normal">n</mml:mi> </mml:mrow> </mml:mrow> <mml:mo>+</mml:mo> </mml:msup> </mml:mrow> <mml:mtext>-</mml:mtext> <mml:mrow class="MJX-TeXAtom-ORD"> <mml:mrow class="MJX-TeXAtom-ORD"> <mml:mi mathvariant="normal">A</mml:mi> <mml:mi mathvariant="normal">l</mml:mi> <mml:mi mathvariant="normal">G</mml:mi> <mml:mi mathvariant="normal">a</mml:mi> <mml:mi mathvariant="normal">N</mml:mi> </mml:mrow> </mml:mrow> </mml:math> TJ with a 0.70 aluminum molar fraction. In addition, the TJ LED emitted power has been improved significantly by 2.5 times compared with a conventional LED structure. Such an efficient <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"> <mml:mrow class="MJX-TeXAtom-ORD"> <mml:msup> <mml:mrow class="MJX-TeXAtom-ORD"> <mml:mrow class="MJX-TeXAtom-ORD"> <mml:mi mathvariant="normal">n</mml:mi> </mml:mrow> </mml:mrow> <mml:mo>+</mml:mo> </mml:msup> </mml:mrow> <mml:mtext>-</mml:mtext> <mml:mrow class="MJX-TeXAtom-ORD"> <mml:mrow class="MJX-TeXAtom-ORD"> <mml:mi mathvariant="normal">A</mml:mi> <mml:mi mathvariant="normal">l</mml:mi> <mml:mi mathvariant="normal">G</mml:mi> <mml:mi mathvariant="normal">a</mml:mi> <mml:mi mathvariant="normal">N</mml:mi> </mml:mrow> </mml:mrow> </mml:math> TJ-based DUV LED at 254 nm emission might open a new way, to the best of our knowledge, for the development of safe and efficient germicidal irradiation sources.

Topics & Concepts