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Investigation of Mg and Si doping at different temperature for multi-color micro-LEDs with tunnel junctions (Conference Presentation)
Author(s): Yoann Robin; Quentin Bournet; Markus Pristovsek; Yamina Andre; Hiroshi Amano
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Paper Abstract

We demonstrate the fabrication of 100 x 100µm2 nitride-based tricolor micro-LEDs. While the optical properties of the devices are very promising, the electrical characterizations show large penalty voltage due to the introduction of compensating defects in the p-GaN layers upon plasma etching. Therefore, we consider replacing the p-GaN layers by p+/n+ tunnel junctions. We analyzed the surface morphology and the Mg, Si, H and C concentration of different p/n junctions grown at different temperature. SIMS results show the C concentration drastically increases from 10^16/cm3 at 1100°C to about 10^17/cm3 at 975°C without significantly affecting the electrical properties of both p- and n-type layers. However, the decomposition of tetramethylsilane (TMSi) strongly depends on the growth temperature, and thus the Si/Ga ratio has to be carefully controlled with temperature. The Mg shows a strong memory effect in the n-side since its concentration is slowly decaying of only one decade after 50nm from the p/n interface. The pining of the Fermi level, close to the conduction band in the n-GaN, destabilizes the Mg-H complex and allows the Mg to be activated (Mg/H<<1). In addition, at the high Mg/Ga and Si/Ga ratio typically required in p+/n+ tunnel junction, we observed a change of the GaN surface morphology with the promotion of inversion domains and 3D growth respectively, whatever the growth temperature. Based on these data, we show that a p+/n+ tunnel junction is a trade off between high structural and electrical quality.

Paper Details

Date Published: 5 March 2019
Proc. SPIE 10918, Gallium Nitride Materials and Devices XIV, 109181U (5 March 2019); doi: 10.1117/12.2506959
Show Author Affiliations
Yoann Robin, Institute of Materials and Systems for Sustainability, Nagoya Univ. (Japan)
Quentin Bournet, Polytech Clermont-Ferrand (France)
Markus Pristovsek, Institute of Materials and Systems for Sustainability, Nagoya Univ. (Japan)
Yamina Andre, Institut Pascal, CNRS (France)
Hiroshi Amano, Institute of Materials and Systems for Sustainability, Nagoya Univ. (Japan)

Published in SPIE Proceedings Vol. 10918:
Gallium Nitride Materials and Devices XIV
Hiroshi Fujioka; Hadis Morkoç; Ulrich T. Schwarz, Editor(s)

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