We present an electro-optical method for the extrapolation of the nonradiative and Auger recombination coefficients in InGaN/GaN Light-emitting diodes (LEDs). The method has the advantage of permitting the extrapolation of the recombination parameters of packaged devices, contrary to conventional techniques based on the analysis of quasibulk structures. For the analyzed devices, the average values of the nonradiative and Auger recombination coefficients have been determined to be equal to $2.3\times {10}^7{\text{s}}^{-1}$ and $1.0\times {10}^{-30}{\text{cm}}^6{\text{s}}^{-1}$ , respectively. These results are consistent with previous reports based on the analysis of quasibulk structures and on theoretical simulations. The method described in this paper constitutes an efficient tool for the analysis of the recombination dynamics in GaN-based LEDs. The results obtained within this work support the hypothesis on the importance of Auger recombination in determining the so-called efficiency droop in LED structures.

Over the last 20 years, the technological improvements of CdTe solar cell have been impressive, and today the performance of these cells is comparable with that of silicon cells. Behind these important results, there have been important research efforts, aimed at exploring every single aspect related to CdTe cell optimization. One of these is reliability, that is fundamental in the perspective of massive commercialization. The aim of this review paper is to explore the main aspects related to the operation and reliability of CdTe solar cells, and describe the most relevant results presented in the literature on these topics. The paper is divided in two parts. The first is dedicated to a general introduction of CdTe issues. In this part, we report the most relevant details on CdTe solar cells from a reliability perspective, including (a) a description of the CdTe solar cells development on the years, (b) a description of the main production methods, (c) an overview of the main mathematical model to describe a solar cell, and (d) the main normative requirements related to solar cell reliability. The second section describes the most important papers in the field of CdTe solar cell reliability, along with two recent case studies, that can be used as an example to understand the complexity of the involved processes. The results are critically discussed by considering the most recent literature on the topic, to provide a general overview to the reader willing to approach the topic.

This paper reports an extensive analysis of the properties of the deep level responsible for the degradation of InGaN-based laser diodes. The analysis is based on combined optical measurements and Deep-Level Transient Spectroscopy (DLTS) investigation. Results indicate that stress induces a significant increase in threshold current of the devices, which is strongly correlated to the increase in the concentration of a deep level (DL) detected by DLTS. The DL involved in the degradation process is located 0.35–0.45 eV below the conduction band. 2D simulation indicates that degradation occurs within the quantum-well region.

This paper reports on the degradation mechanisms that limit the reliability of high-power light-emitting diodes (LEDs) for lighting applications. The study is based on the experimental characterization of state-of-the-art LEDs fabricated by leading manufacturers. We demonstrate that, despite high potential reliability, high-power LEDs may suffer from a number of degradation mechanisms that affect the stability of the blue semiconductor LED chip and of the phosphor layer used for the generation of white light. More specifically, we describe the following relevant mechanisms: 1) the optical degradation of LEDs, due to an increase in the nonradiative recombination rate, which can be correlated to modifications in the forward-bias current-voltage characteristics; 2) the variation in forward voltage, due to the increase in series resistance; 3) the optical degradation of phosphor layers used for blue-to-white light conversion; and 4) the failure of LEDs submitted to “hot plugging,” which is the direct connection of an LED chain to an energized power supply, due to the generation of high current spikes. Results provide an overview on the failure mechanisms that limit the reliability of state-of-the-art LEDs and on the role of current and temperature in determining the failure of the devices.