Multi-Layer Contact Structure for Light Emitting Devices
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Solution Overview
Problem
Existing light emitting devices face challenges in reducing operation voltages and enhancing light extraction efficiency, particularly in the design of semiconductor layers and electrode structures.
Innovation Solution
A light emitting device is designed with a multi-contact layer comprising InGaN and GaN layers doped with specific dopants, a transparent electrode layer, and a unique electrode structure to reduce operation voltages and improve light extraction efficiency, featuring a stacked semiconductor layer configuration with a well and barrier layer structure in the active layer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If a conventional single-layer contact structure is used, then the device structure is simple, but the operation voltage cannot be effectively reduced
Solution Approach 1:
The contact structure is divided into multiple layers with different materials and doping types. The multi-layer contact structure includes an n-type doped layer, a p-type doped layer, and an undoped layer, each serving specific functions to reduce operation voltage through optimized carrier injection and electric field distribution.
Solution Approach 2:
The contact structure uses composite material design combining different semiconductor materials (GaN, InGaN) with varying band gaps and doping characteristics. This composite approach enables tailored electrical properties at different interfaces, facilitating lower operation voltage while maintaining structural integrity.
2Ease of manufacture
If the semiconductor layer structure is simplified, then the manufacturing process is easier, but the light extraction efficiency is reduced
Solution Approach 1:
The active layer employs a quantum well structure with localized regions of different band gaps. The well layer has a smaller band gap for efficient light emission, while the barrier layer has a larger band gap to confine carriers. This local quality variation optimizes light extraction efficiency without complicating the overall manufacturing process.
Solution Approach 2:
The quantum well structure nests the well layer within the barrier layer, creating a confined potential well that traps carriers and enhances radiative recombination. This nested configuration improves light extraction efficiency while maintaining a relatively simple layered structure that can be manufactured using standard epitaxial techniques.
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 effectively reduces operation voltages and enhances light extraction efficiency by optimizing the semiconductor layer and electrode structure, leading to improved performance and reliability of the light emitting device.
Implementation Method 1
the second conductivity type semiconductor layer and the multi-contact layer are doped with an opposite conductivity type dopant and p-n junction is formed between the second conductivity type semiconductor layer and the multi-contact layer
Implementation Method 2
a light emitting structure comprising a first conductivity type semiconductor layer, an active layer and a second conductivity type semiconductor layer... the active layer comprises a well layer and a barrier layer which are alternatively stacked at least one time, and an energy band gap of the well layer is smaller than an energy band gap of the barrier layer
Data Source
Figure 1~2a
Figure 2b~2c
Figure 2d~2e
AI summary
A light emitting device includes a light emitting structure (120) comprising a first conductive type semiconductor layer (122), an active layer (124) and a second conductive type semiconductor layer (126), wherein the active layer (124) comprises well- and barrier layers alternatively stacked at least once; a multi-layer contact (200) disposed on at least a predetermined region of the second conductive type semiconductor layer (126), the multi-layer contact (200) comprising at least one layer pair of a first layer comprising InGaN having a first dopant and a second layer comprising GaN having a second dopant; and a first electrode (195) and a second electrode (190) to provide currents to the first and second conductive type semiconductor layer, respectively.