Thank you for attending Photonics West 2022
Conference 12001 > Paper 12001-19
Paper 12001-19

Deep defects in InGaN LEDs: modeling the impact on the electrical characteristics

25 January 2022 • 10:30 AM - 10:50 AM PST | Room 152 (Upper Mezzanine South)

Abstract

Deep defects have a fundamental role in determining the electro-optical characteristics and in the efficiency of InGaN light-emitting diodes (LEDs). However, modeling their effect on the electrical characteristics of the LED is not straightforward.

In this paper we analyze the impact of the defects on the electrical characteristics of LEDs: we analyze three single-quantum-well (SQW) InGaN/GaN LED wafers, which differ in the density of defects. Through steady-state photocapacitance (SSPC) and light-capacitance-voltage measurements, the energy levels of these deep defects and their concentrations have been estimated.

By means of a simulation campaign, we show that these defects have a fundamental impact on the current voltage characteristic of LEDs, especially in the sub turn-on region. The model adopted takes into consideration trap assisted tunneling as the main mechanism responsible for current leakage in forward bias.

For the first time, we use in simulations the defect parameters (concentration, energy) extracted from SSPC. In this way, we can reproduce with great accuracy the current-voltage characteristics of InGaN LEDs in a wide current range (from pA to mA).

In addition, based on SSPC measurements, we demonstrate that the defect density in the active region scales with the QW thickness. This supports the hypothesis that defects are incorporated in In-containing layers, consistently with recent publications.

Presenter

Univ. degli Studi di Padova (Italy)
Matteo Buffolo was born in Vittorio Veneto (Italy) in November 1986. In 2014 he received a Master Degree in Electronic Engineering from the University of Padova, with a thesis focusing on the analysis of the degradation mechanisms of GaN-based mid-power white LEDs. On March 2018 he achieved its PhD at the Department of Information Engineering at the University of Padova, where he is actually working as a post-doc. His research interests focus on the reliability of lighting systems employing GaN-based devices (lasers and LEDs) and on the investigation of the degradation mechanisms that affect modern IR laser sources for integrated telecommunication applications.
Author
Nicola Roccato
Univ. degli Studi di Padova (Italy)
Author
Univ. degli Studi di Padova (Italy)
Author
Univ. degli Studi di Padova (Italy)
Author
Univ. degli Studi di Padova (Italy)
Author
Univ. degli Studi di Padova (Italy)
Presenter/Author
Univ. degli Studi di Padova (Italy)
Author
Ecole Polytechnique Fédérale de Lausanne (Switzerland)
Author
Jean-François Carlin
Ecole Polytechnique Fédérale de Lausanne (Switzerland)
Author
Ecole Polytechnique Fédérale de Lausanne (Switzerland)
Author
Marco Vallone
Politecnico di Torino (Italy)
Author
Alberto Tibaldi
Politecnico di Torino (Italy)
Author
Francesco Bertazzi
Politecnico di Torino (Italy)
Author
Michele Goano
Politecnico di Torino (Italy)
Author
Giovanni Verzellesi
Univ. degli Studi di Modena e Reggio Emilia (Italy)
Author
Univ. degli Studi di Padova (Italy)
Author
Univ. degli Studi di Padova (Italy)
Author
Univ. degli Studi di Padova (Italy)