Vertical LED With Patterned Groove and Reflective Layer
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Solution Overview
Problem
Conventional LEDs with a horizontal structure suffer from low thermal conductivity and increased forward voltage due to current crowding, while vertical structure LEDs face reduced light-emitting efficiency and brightness due to photon absorption by the n-type electrode, and the current-blocking layer increases forward voltage by reducing the ohmic contact area.
Innovation Solution
A light-emitting device with a vertical structure featuring a patterned groove on the p-type semiconductor layer, a current-blocking layer at the groove bottom, a transparent conductive layer with alternating horizontal and vertical portions, and a reflective layer to enhance light emission and prevent forward voltage increase, along with a method for manufacturing this device.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If a current-blocking layer is formed on the p-type semiconductor layer to concentrate current flow horizontally, then light-emitting intensity and brightness are enhanced, but the ohmic contact area is reduced resulting in increased forward voltage
Solution Approach 1:
The patent divides the current-blocking layer into multiple segments separated by grooves, creating multiple current flow paths instead of a single concentrated path. This segmentation maintains current concentration benefits for light emission while distributing the current flow to preserve adequate ohmic contact area, thereby reducing forward voltage.
Solution Approach 2:
The patent applies local quality by creating regions with different current-blocking characteristics - some areas have current-blocking layers to concentrate current for enhanced light emission, while other areas (groove regions) allow current flow to maintain ohmic contact. This spatial variation in local properties resolves the contradiction between current concentration and contact area.
2Use of energy by moving object
If photons are concentrated to the central part below the n-type electrode, then recombination efficiency is improved, but the effective light emission region is reduced due to photon absorption by the electrode
Solution Approach 1:
The patent introduces a vertical dimension solution by forming a reflective layer beneath the active layer and p-type semiconductor layer. This reflective layer redirects photons that would otherwise be absorbed by the n-type electrode back into the light-emitting region, effectively utilizing the vertical space and converting a harmful absorption path into a beneficial light extraction path.
Solution Approach 2:
The patent converts the harmful photon absorption by the n-type electrode into a beneficial effect by placing a reflective layer that bounces these photons back into the active region, allowing them to contribute to light emission rather than being lost. This transforms the electrode's photon-absorbing property from a disadvantage into an opportunity for enhanced light extraction through reflection.
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 increases the ohmic contact area and current flow path, enhancing optical output characteristics and preventing forward voltage increase by distributing current effectively across the semiconductor layers, thereby improving light-emitting efficiency and brightness.
Implementation Method 1
a reflective layer which is formed on one surface of the transparent conductive layer opposite to another surface thereof that is in contact with the second conductive semiconductor layer
Implementation Method 2
A light-emitting device is a device to emit light to outside by converting electric energy into light energy
Data Source
AI summary
The present invention relates to a light-emitting device that is capable of preventing an increase in forward voltage while improving optical output characteristics, and to a method for manufacturing same. The light-emitting device comprises: a first conductive semiconductor layer; an active layer which is in contact with the first conductive semiconductor layer; a second conductive semiconductor layer which is in contact with the active layer and which has a patterned groove on a surface opposite the surface that is in contact with the active layer; a current-blocking layer which is formed on a bottom of the groove; a transparent conductive layer which is formed along a surface opposite the surface of the second conductive semiconductor layer that is in contact with the active layer, a sidewall of the groove, and the current-blocking layer; a reflective layer which is formed on a surface opposite the surface of the transparent conductive layer that is in contact with the second conductive semiconductor layer; a support substrate which is formed on a surface opposite the surface of the reflective layer that is in contact with the transparent conductive layer; and an electrode that is patterned on a surface opposite the surface of the first conductive semiconductor layer that is in contact with the active layer.