Five-year outcomes of chronic total occlusion treatment with a biolimus A9-eluting biodegradable polymer stent versus a sirolimus-eluting permanent polymer stent in the LEADERS all-comers trial

Background: Few data are available on long-term follow-up of drug-eluting stents in the treatment of chronic total occlusion (CTO). The LEADERS CTO sub-study compared the long-term results in CTO and non-CTO lesions of a Biolimus A9™-eluting stent (BES) with a sirolimus-eluting stent (SES). Methods: Among 1,707 patients enrolled in the prospective, multi-center, all-comers LEADERS trial, 81 with CTOs were treated with either a BES (n = 45) or a SES (n = 36). The primary endpoint was the occurrence of major adverse cardiac events (MACE): cardiac death, myocardial infarction (MI) and clinically-indicated target vessel revascularization (TVR). Results: At 5 years, the rate of MACE was numerically higher in the CTO group than in the non-CTO group (29.6% vs. 23.3%; p = 0.173), with a significant increase in the incidence of target lesion revascularization (TLR) (21.0 vs. 12.6; p = 0.033), but no difference in stent thrombosis (ST). Patients with CTO receiving a BES demonstrated a lower incidence of MACE (22.2% vs. 38.9%; p = 0.147) with a significant reduction in TLR compared to patients receiving a SES (11.1% vs. 33.3%, p = 0.0214) with an incidence similar to that observed in the non-CTO group treated with BES (11.6%). Definite ST at 5 years nearly halved in the BES group (4.4% vs. 8.3%, p = 0.478) with no ST in the BES group after the first year (0% vs. 8.3%, p for interaction = 0.009). Conclusions: The use of a BES showed a reduction in MACE, TVR, TLR, and ST over time in the CTO subset with similar outcome as for non-CTO lesions

Semiclassical simulation of trap-assisted tunneling in GaN-based light-emitting diodes

We present a combined theoretical, numerical and experimental investigation on trap-assisted tunneling (TAT) in the subthreshold regime of III-nitride-based light-emitting diodes (LEDs). Starting from the basic formulation of the TAT models provided by Hurkx and Schenk, we discuss the derivation of a detailed approach based on both multiphonon and elastic nonlocal processes. A sensitivity study conducted over the main trap- and phonon-related physical parameters of this nonlocal TAT model confirms the importance of tunneling assisted by lattice defects on the LED electrical behavior in the low-medium forward bias range. Comparisons with measured temperature-dependent electrical characteristics I(V;T) of a single quantum well LED grown on a highly conductive SiC substrate demonstrate that I(V;T) can be accurately reproduced in the range between 200 and 400\ua0K by implementing the nonlocal model for TAT processes via traps in the electron-blocking and spacer layers. \ua9 2015, Springer Science+Business Media New York

Physics-based modeling and experimental implications of trap-assisted tunneling in InGaN/GaN light-emitting diodes

In a combined experimental and numerical investigation, we present the effects of trap-assisted tunneling on the sub-threshold forward bias characteristics of a blue InGaN/GaN single-quantum-well LED test structure grown on a SiC substrate. The different role of donor- and acceptor-like traps has been studied, for the information it can provide on the role played by point defects. Using the energy Et and trap density Nt as the only tunneling-related fitting parameters, the behavior of the measured I(V) curves is well reproduced by our model over a wide current and temperature range. The very good agreement between simulations and experiments suggests that trap-assisted forward tunneling is one of the most relevant contributions to the current flow below the optical turn-on of the diode. \ua9 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim

Trap-assisted tunneling in InGaN/GaN LEDs: Experiments and physics-based simulation

We present results from a combined experimental and numerical investigation of a blue InGaN/GaN LED test structure grown on a SiC substrate, confirming that tunneling represents a critical contribution to the sub-threshold forward bias current and discussing the relative importance of different trap-assisted electron tunneling processes

Trap-assisted tunneling contributions to subthreshold forward current in InGaN/GaN light-emitting diodes

We present results from a combined experimental and numerical investigation of trap-assisted tunneling contributions to subthreshold forward current in InGaN/GaN light-emitting diodes. We show that the excess forward leakage current in single-quantum-well InGaN/GaN light-emitting diodes can be explained by non-local tunneling-into-traps processes and subsequent non-radiative recombination with free carriers. \ua9 2015 SPIE

Effects of Dislocation Density on Injection and Temperature Sensitivity of InGaN LED Emission Spectra: a Combined Experimental and Simulation Approach

The aim of this paper is to describe a combined simulation and characterization activity carried out on blue LEDs grown on templates with different threading dislocation densities (TDDs)