LED Stacked Structure with Tunnel Diode for Current Control
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Solution Overview
Problem
Existing light emitting diodes (LEDs) face inefficiencies in current decoupling and light emission due to vertical current flow, which affects their luminous flux and power consumption efficiency.
Innovation Solution
A stacked structure of III-V semiconductor layers with a tunnel diode and injection barrier is implemented, featuring a p+/n+ junction and insulating layers to suppress counter-current flow, enhancing light efficiency by minimizing current injection below the bonding pad and optimizing the semiconductor material arrangement for improved emission.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a conventional LED structure with contact layer and active region is used, then current injection is achieved, but vertical current flow from contact to active region causes inefficiency in decoupling and reduces luminous flux efficiency
Solution Approach 1:
The contact structure is segmented into multiple functional layers: n-doped contact layer, n-doped current distribution layer, and tunnel diode structure (p+-layer/n+-layer). This segmentation allows separate optimization of current injection, current spreading, and current blocking functions, preventing direct vertical current flow while maintaining efficient current injection into the active region.
Solution Approach 2:
The tunnel diode structure acts as an intermediary between the contact layer and active region. The p+/n+ junction with its specific band structure serves as a mediator that allows efficient electron injection while blocking holes and preventing reverse current flow, thus resolving the contradiction between current injection efficiency and decoupling efficiency.
2Ease of operation
If the entire LED surface is covered with contact layers and metallization, then electrical contacting is achieved, but light emission is blocked in those areas
Solution Approach 1:
Different regions of the LED surface are assigned different functions: the first region (emission region) is optimized for light emission with transparent or minimal contact structures, while the second region (contact region) is optimized for electrical contacting with full metallization coverage. This local differentiation allows both functions to coexist without mutual interference.
Solution Approach 2:
The contact structures in the second region are designed to extend laterally beyond the active region boundaries, utilizing the lateral dimension to separate contact functions from emission functions. This dimensional separation allows complete electrical coverage without compromising light emission areas.
3Reliability
If current distribution layers and tunnel diodes are present across the entire structure, then current control is improved, but manufacturing complexity increases
Solution Approach 1:
The advanced current control structure (current distribution layer + tunnel diode) is segmented and applied only to specific regions where needed. The first region receives the full current control treatment, while the second region uses simplified contact structures, reducing overall manufacturing complexity while maintaining current control precision where required.
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 solution significantly increases light efficiency by reducing counter-current flow and enhancing luminous flux per power consumption, achieving higher LED performance through selective etching and material layer configurations.
Implementation Method 1
An injection barrier formed flat in the upper cladding layer or on the surface of the upper cladding layer or above the upper cladding layer, in order to suppress a current flow counter to the stacking direction, wherein the injection barrier comprises a p/n-junction and/or an insulating layer
Implementation Method 2
an electromagnetic radiation-generating active layer, wherein the active layer comprises a quantum well structure
Data Source
AI summary
A light emitting diode with a stacked structure, having a first region and a second region, wherein both regions comprise the following layers in the stated order, a carrier layer and an n-doped lower cladding layer and an electromagnetic radiation-generating active layer. The active layer comprises a quantum well structure and a p-doped upper cladding layer, and the first region additionally comprises a tunnel diode formed on the upper cladding layer from a p+-layer and an n+-layer, and an n-doped current distribution layer, wherein the current distribution layer and the n-doped contact layer are covered with a conductor track layer structure. At least the lower cladding layer, the active layer, the upper cladding layer, the tunnel diode and the current distribution layer are monolithic. The second region has a contact hole with a bottom region, an injection barrier being formed in the bottom region of the contact hole.