LED Active-Inactive Region Layout for Quantum Efficiency and Sharpness
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Solution Overview
Problem
Current light emitting diodes (LEDs) for direct view display devices face challenges in achieving optimal external quantum efficiency and image sharpness due to limitations in the design of electrically active and inactive regions, which affect the conductivity and light emission characteristics.
Innovation Solution
The solution involves forming light emitting diodes with a p-doped semiconductor material layer that includes an electrically active region partially covered by an anode contact and an inactive region with reduced electrical conductivity, achieved through plasma treatment, to optimize the interface area and operating voltage for peak external quantum efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the anode contact area is increased to reduce operating voltage, then the electrical conductivity improves, but the external quantum efficiency decreases due to increased non-radiative recombination
Solution Approach 1:
The patent applies local quality by creating distinct regions within the p-doped semiconductor layer: an electrically active region with high conductivity for efficient current injection, and an optically active region with controlled conductivity for efficient light emission. This spatial differentiation of electrical properties allows simultaneous optimization of both electrical conductivity and external quantum efficiency without compromise
Solution Approach 2:
The p-doped semiconductor layer is segmented into functionally distinct zones: an electrically active region that serves as the primary current injection path, and an optically active region that minimizes non-radiative recombination. This segmentation enables independent optimization of electrical and optical performance in different spatial locations
2Use of energy by moving object
If the active region area is increased to improve light emission, then the external quantum efficiency improves, but the image sharpness deteriorates due to increased pixel crosstalk
Solution Approach 1:
The patent implements local quality by creating an inactive region with reduced electrical conductivity that acts as an electrical isolation barrier between adjacent pixels. This allows the active emission region to be sufficiently large for high external quantum efficiency while preventing lateral current spread that would cause pixel crosstalk and degrade image sharpness
Solution Approach 2:
The inactive region serves as an intermediary element between adjacent active regions, providing electrical isolation through its reduced conductivity. This intermediary structure enables larger active emission areas without compromising image sharpness, as it blocks lateral current diffusion between pixels
3Loss of energy
If the operating voltage is reduced to decrease power consumption, then the energy efficiency improves, but the current density control becomes less effective
Solution Approach 1:
The patent applies local quality by designing the electrically active region with optimized doping concentration and geometry to provide low resistance current injection at reduced voltages. Simultaneously, the inactive region maintains sufficient electrical isolation to preserve current confinement and control, enabling effective operation at lower voltages without sacrificing current density management
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 enhances the external quantum efficiency of LEDs and improves image sharpness by controlling the current density and electrical conductivity, resulting in better light emission and display performance.
Implementation Method 1
deactivating a physically exposed portion of the p-doped semiconductor material layer with a plasma treatment to form an inactive region
Implementation Method 2
an active region including an optically active compound semiconductor layer stack configured to emit light
Implementation Method 3
optically active compound semiconductor layer stack configured to emit light
Implementation Method 4
a reflector overlying and electrically connected to the anode contact
Data Source
AI summary
A light emitting device (LED) includes an n-doped semiconductor material layer, an active region including an optically active compound semiconductor layer stack configured to emit light located on the n-doped semiconductor material layer, a p-doped semiconductor material layer located on the active region, an anode contact contacting the p-doped semiconductor material layer, a reflector overlying and electrically connected to the anode contact, and a device-side bonding pad layer located on the reflector. The p-doped semiconductor material layer includes an electrically active region that is at least partially covered by the anode contact and an inactive region that an electrical conductivity less than 30% of the electrically active region.