Quantitative Multi‐Scale, Multi‐Physics Quantum Transport Modeling of GaN‐Based Light Emitting Diodes

It has recently been proposed that back‐contacted III–V light‐emitting diodes (LEDs) could offer improved current spreading as compared to conventional mesa or double side contacted structures. This has inspired also experimental efforts to realize such structures, but fabrication methods for them have not yet been fully established. Herein, the use of unintentionally doped and partially carrier‐selective contacts (SC) is studied to realize back‐contacted indium gallium nitride (InGaN) LEDs. The sharp electroluminescence peak at 439 nm from the multiquantum well stack demonstrates that the approach allows fabricating back‐contacted InGaN LEDs without intentionally doped n‐GaN layers and without inflicting damage in the active region, often observed in alternative approaches relying on lateral doping and the use of high energy particles during fabrication. The samples are fabricated on a finger configuration with several finger widths between 1 and 20 μm. It is observed that the emission spreads most uniformly throughout the structure for fingers with the width of 5 μm. As shown by the simulations, with improved contact resistances, the structures reported herein could enable fabricating back‐contacted LEDs with unity injection efficiency and improved current spreading, offering a path toward large‐area LEDs without contact shading even in materials where n‐doping is elusive.

show abstract

“…The recombination parameters represent established values frequently used in corresponding simulations. [ 31–33 ]…”

Section: Simulationsmentioning

confidence: 99%

Back‐Contacted Carrier Injection for Scalable GaN Light Emitters

Kim

Kauppinen

Radevici

et al. 2021

Physica Status Solidi (a)

View full text Add to dashboard Cite

show abstract

“…Quantum mechanical transport models based on the Non-Equilibrium Green’s Function (NEGF) method have been published more recently [ 18 , 19 ]. Such models are especially valuable in the investigation of tunneling and carrier leakage processes.…”

Section: Carrier Transport Modelsmentioning

confidence: 99%

Efficiency Models for GaN-Based Light-Emitting Diodes: Status and Challenges

Piprek¹

2020

Materials

View full text Add to dashboard Cite

Light-emitting diodes (LEDs) based on Gallium Nitride (GaN) have been revolutionizing various applications in lighting, displays, biotechnology, and other fields. However, their energy efficiency is still below expectations in many cases. An unprecedented diversity of theoretical models has been developed for efficiency analysis and GaN-LED design optimization, including carrier transport models, quantum well recombination models, and light extraction models. This invited review paper provides an overview of the modeling landscape and pays special attention to the influence of III-nitride material properties. It thereby identifies some key challenges and directions for future improvements.

show abstract

“…Simulations of full LED structures are usually performed in 1D [78][79][80][81][82] because of the computational challenges to include 3D disorder. LED simulations are based on a known 1D map of the band edges of the devices (eventually computing the QW levels with a 1D Schrödinger equation), solving throughout the device structure driftdiffusion (DD) equations that involve knowing local transport parameters of carriers (mobilities, diffusion coefficients, both being related by the Einstein relation D = (kT/e)μ for homogeneous systems at equilibrium) and recombination times of carriers.…”

Section: Simulation Of Leds-without Disorder Taken Into Accountmentioning

confidence: 99%

Disorder effects in nitride semiconductors: impact on fundamental and device properties

Weisbuch

Nakamura

et al. 2020

Nanophotonics

View full text Add to dashboard Cite

Semiconductor structures used for fundamental or device applications most often incorporate alloy materials. In “usual” or “common” III–V alloys, based on the InGaAsP or InGaAlAs material systems, the effects of compositional disorder on the electronic properties can be treated in a perturbative approach. This is not the case in the more recent nitride-based GaInAlN alloys, where the potential changes associated with the various atoms induce strong localization effects, which cannot be described perturbatively. Since the early studies of these materials and devices, disorder effects have indeed been identified to play a major role in their properties. Although many studies have been performed on the structural characterization of materials, on intrinsic electronic localization properties, and on the impact of disorder on device operation, there are still many open questions on all these topics. Taking disorder into account also leads to unmanageable problems in simulations. As a prerequisite to address material and device simulations, a critical examination of experiments must be considered to ensure that one measures intrinsic parameters as these materials are difficult to grow with low defect densities. A specific property of nitride semiconductors that can obscure intrinsic properties is the strong spontaneous and piezoelectric fields. We outline in this review the remaining challenges faced when attempting to fully describe nitride-based material systems, taking the examples of LEDs. The objectives of a better understanding of disorder phenomena are to explain the hidden phenomena often forcing one to use ad hoc parameters, or additional poorly defined concepts, to make simulations agree with experiments. Finally, we describe a novel simulation tool based on a mathematical breakthrough to solve the Schrödinger equation in disordered potentials that facilitates 3D simulations that include alloy disorder.

show abstract

Quantitative Multi‐Scale, Multi‐Physics Quantum Transport Modeling of GaN‐Based Light Emitting Diodes

Cited by 26 publications

References 30 publications

Back‐Contacted Carrier Injection for Scalable GaN Light Emitters

Back‐Contacted Carrier Injection for Scalable GaN Light Emitters

Efficiency Models for GaN-Based Light-Emitting Diodes: Status and Challenges

Disorder effects in nitride semiconductors: impact on fundamental and device properties

Contact Info

Product

Resources

About