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Proceedings Paper

Thermal droop in InGaN-based LEDs: physical origin and dependence on material properties
Author(s): C. De Santi; M. Meneghini; M. La Grassa; N. Trivellin; B. Galler; R. Zeisel; B. Hahn; M. Goano; S. Dominici; M. Mandurrino; F. Bertazzi; G. Meneghesso; E. Zanoni
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Paper Abstract

The thermal droop (reduction of the optical power when the temperature is increased) is a phenomenon that strongly limits the efficiency of InGaN-based light-emitting diodes. In this paper we analyze the role of Shockley-Read-Hall (SRH) recombination and of the electron blocking layer (EBL) in the process by using numerical simulations and literature data. The benefic impact of EBL suggests that carrier escape from the quantum wells gives a significant contribution to the thermal droop, therefore we review some of the mechanisms described in the literature (thermionic emission, phonon-assisted tunneling, thermionic trap-assisted tunneling). Since no formulation is able to fit the behavior of the measured SQW devices, we develop a new model based on two phonon-assisted tunneling steps through a defective state, extended in order to take into account zero-field emission. By using experimental data, material constants from the literature and only two fitting parameters the model is able to reproduce the experimental behavior.

Paper Details

Date Published: 8 March 2016
PDF: 8 pages
Proc. SPIE 9768, Light-Emitting Diodes: Materials, Devices, and Applications for Solid State Lighting XX, 97680D (8 March 2016); doi: 10.1117/12.2210953
Show Author Affiliations
C. De Santi, Univ. degli Studi di Padova (Italy)
M. Meneghini, Univ. degli Studi di Padova (Italy)
M. La Grassa, Univ. degli Studi di Padova (Italy)
N. Trivellin, Univ. degli Studi di Padova (Italy)
B. Galler, OSRAM Opto Semiconductors GmbH (Germany)
R. Zeisel, OSRAM Opto Semiconductors GmbH (Germany)
B. Hahn, OSRAM Opto Semiconductors GmbH (Germany)
M. Goano, Politecnico di Torino (Italy)
S. Dominici, Politecnico di Torino (Italy)
M. Mandurrino, Politecnico di Torino (Italy)
F. Bertazzi, Politecnico di Torino (Italy)
G. Meneghesso, Univ. degli Studi di Padova (Italy)
E. Zanoni, Univ. degli Studi di Padova (Italy)

Published in SPIE Proceedings Vol. 9768:
Light-Emitting Diodes: Materials, Devices, and Applications for Solid State Lighting XX
Heonsu Jeon; Li-Wei Tu; Michael R. Krames; Martin Strassburg, Editor(s)

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