LED Current Confinement via Pillar Structure
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Solution Overview
Problem
Current semiconductor-based LEDs face efficiency droop issues due to high current densities, which are exacerbated by the large size of LED dies, making it difficult to maintain high luminous efficacy and luminance, especially at lower current densities.
Innovation Solution
The development of LED devices with a confined current injection area, where a current spreading layer pillar is doped with a specific dopant type and protrudes from a cladding layer, allowing for reduced current injection area and increased efficiency by confining current internally within the active layer, reducing non-radiative recombination and enhancing internal quantum efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If LED die size is increased to reduce current density and efficiency droop, then luminous efficacy is improved, but device area increases and integration into compact form factors becomes difficult
Solution Approach 1:
The patent applies local quality by creating a current spreading layer pillar with a specific dopant type that protrudes from the cladding layer, concentrating current injection in a localized region rather than distributing it uniformly across a large area. This allows small LED dies to achieve high current density in the active region without requiring large overall device area, thus maintaining high luminous efficacy while enabling compact form factors.
2Use of energy by moving object
If current density is increased to improve luminous efficacy, then light emission efficiency increases, but efficiency droop occurs at higher current densities
Solution Approach 1:
The patent employs parameter changes by modifying the dopant type and concentration in the current spreading layer pillar, and by controlling the protrusion height and cross-sectional area of the pillar. These parameter adjustments optimize current confinement and injection efficiency, enabling operation at current densities that achieve high luminous efficacy while avoiding the efficiency droop region through precise control of electrical and geometric parameters.
3Use of energy by moving object
If current injection area is reduced to increase current density and efficiency, then luminous efficacy improves, but manufacturing precision requirements increase
Solution Approach 1:
The patent uses the current spreading layer pillar as an intermediary structure that mediates between the electrode and the active layer. By introducing this intermediate element with controlled geometry and dopant profile, the system achieves precise current confinement without requiring extreme manufacturing precision in the final active region, as the pillar itself serves as the precision-controlled element that can be fabricated using standard semiconductor processes.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This design enables LED devices to operate efficiently at lower current densities, achieving higher luminous efficacy and luminance while consuming less power, and allows for integration into smaller form factors, such as portable electronic devices, without the need for larger LED sizes.
Implementation Method 1
The first current spreading layer pillar is doped with a first dopant type and the second current spreading layer is doped with a second dopant type opposite the first dopant type
Implementation Method 2
Light emitting diodes (LEDs) are increasingly being considered as a replacement technology for existing light sources
Data Source
AI summary
A method and structure for forming an array of LED devices is disclosed. The LED devices in accordance with embodiments of the invention may include a confined current injection area in which a current spreading layer protrudes away from a cladding layer in a pillar configuration so that the cladding layer is wider than the current spreading layer pillar.