Current-Spreading Layer in Nitride LED for Uniform Injection
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Solution Overview
Problem
Conventional nitride-based semiconductor light-emitting devices face issues with current injection, where current tends to congregate in the p-type semiconductor layer under the electrode, leading to inefficient light emission due to blockage by metal extensions used to address this problem.
Innovation Solution
Incorporating a current-spreading layer within the p-type semiconductor stack, which can be undoped or intentionally doped with n-type impurities, to enhance current distribution and reduce the need for extensive metal extensions, thereby minimizing light absorption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If metal extensions are added to address current congregation, then current distribution is improved, but light absorption increases and luminous intensity decreases
Solution Approach 1:
An undoped current spreading layer is introduced as an intermediary component between the p-type semiconductor layer and the electrode. This layer mediates the current distribution by providing a dedicated pathway for current flow without the light-absorbing properties of metal extensions, thus resolving the contradiction between improving current distribution and reducing light absorption.
Solution Approach 2:
The harmful light-absorbing metal extensions are extracted from the device structure. Instead of using metal extensions to address current congregation, the patent removes this harmful element and replaces it with a non-absorbing undoped current spreading layer that performs the current distribution function without the adverse light absorption effect.
2Reliability
If current spreading layer is added, then current spreading is improved, but device complexity increases
Solution Approach 1:
The current spreading function is merged into the semiconductor layer structure itself by using an undoped current spreading layer that is epitaxially grown as part of the semiconductor stack. This integration approach combines the current spreading functionality with the existing semiconductor structure, avoiding the need for separate metal extension components and thus reducing overall device complexity while maintaining improved current spreading.
3Device complexity
If conventional p-type semiconductor layer is used, then structure is simple, but current congregation occurs under electrode
Solution Approach 1:
The patent applies local quality by creating a specific undoped region within the p-type semiconductor stack where current spreading is needed. Instead of uniformly doping the entire p-type layer, the undoped current spreading layer is strategically positioned under the electrode contact area to locally improve current distribution without affecting the overall p-type characteristics needed for hole injection elsewhere in the structure.
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
The current-spreading layer effectively improves current spreading in nitride-based semiconductor light-emitting devices, resulting in higher luminous intensity and reduced light absorption, outperforming conventional designs.
Implementation Method 1
a first current-spreading layer having the first conductivity type interposed in the second semiconductor stack
Implementation Method 2
The light radiation theory of light emitting diode (LED) is to generate light from the energy released by the electron moving between an n-type semiconductor and a p-type semiconductor
Data Source
AI summary
A light-emitting element comprises: a first semiconductor stack having a first conductivity type; an active layer formed on the first semiconductor stack; a second semiconductor stack having a second conductivity type formed on the active layer; and a first current-spreading layer having the first conductivity type interposed in the second semiconductor stack.