Low resistance n-contact for UVC LEDs by a two-step plasma etching process
H.K. Cho1, J.H. Kang1, L. Sulmoni2, K. Kunkel1, J. Rass1, N. Susilo2, T. Wernicke2, S. Einfeldt1 and M. Kneissl1,2
Published in:
Semicond. Sci. Technol., vol. 35, no. 09, pp. 095019, doi:10.1088/1361-6641/ab9ea7 (2020).
Abstract:
The impact of plasma etching on the formation of low-resistance n-contacts on the AlGaN:Si current spreading layer during the chip fabrication of ultraviolet light-emitting diodes (UV LEDs) emitting at 265 nm is investigated. A two-step plasma etching process with a first rapid etching using BCl3/Cl2 gas mixture and a second slow etching step using pure Cl2 gas has been developed. The etching sequence provides smooth mesa side-walls and an n-AlGaN surface with reduced surface damage. Ohmic n-contacts with a contact resistivity of 3.5 × 10-4 Ωcm2 are obtained on Si-doped Al0.65Ga0.35N layers and the operating voltages of the UVC LEDs were reduced by 2 V for a current of 20 mA.
1 Ferdinand-Braun-Institut, Leibniz-Institut für Höchstfrequenztechnik, Gustav-Kirchhoff-Str. 4, 12489 Berlin, Germany
2 Technische Universität Berlin, Institute of Solid State Physics, Hardenbergstr. 36, EW 6-1, 10623 Berlin, Germany
Keywords:
light emitting diode, plasma etch, ohmic contact, low resistance n-contact, high Al mole fraction n-AlGaN, operating voltage
Copyright © 2020 The Author(s). Published by IOP Publishing Ltd. Printed in the UK.
Original content from this work may be used under the terms of the Creative Commons Attribution 4.0 licence. Any further distribution of this work must maintain attribution to the author(s) and the title of the work, journal citation and DOI.
Full version in pdf-format.