Nitride Semiconductor Interface Layer for Light Emitting Device
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Solution Overview
Problem
Current light emitting devices using group III-V or II-VI compound semiconductor materials face limitations in achieving high internal quantum efficiency and efficient light emission due to challenges in controlling electron and hole flow, particularly in asymmetric energy bandgap structures.
Innovation Solution
A light emitting device structure featuring a first and second conductivity-type semiconductor layer with an active layer comprising alternately stacked well and barrier layers made of nitride-semiconductor materials, along with an interface layer having layers with different energy bandgaps, which reduces compressive stresses and enhances electron-hole combination probability, thereby increasing light emission efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a clad layer with asymmetric energy bandgap is used to control electron and hole flow, then internal quantum efficiency is improved, but device structure complexity increases
Solution Approach 1:
The interface layer is divided into three distinct sub-layers (first, second, and third layers) with progressively decreasing energy bandgaps. This segmentation allows independent optimization of each layer's function: the first two layers with higher bandgaps provide electron blocking, while the third layer with lower bandgap facilitates hole injection, achieving efficient carrier control through structured division.
Solution Approach 2:
Different regions of the interface layer are assigned different energy bandgap properties to perform different functions. The first and second layers have higher energy bandgaps than the barrier layer to block electrons, while the third layer has a lower energy bandgap to allow hole passage. This local differentiation of material properties enables precise control of carrier flow without requiring complex external control mechanisms.
2Reliability
If multiple layers with different energy bandgaps are stacked to control carrier flow, then electron-hole combination probability increases, but manufacturing precision requirements increase
Solution Approach 1:
The interface layer utilizes systematic variation of energy bandgap parameters across three sub-layers. By changing the energy bandgap parameter progressively (first layer > second layer > third layer), the structure creates favorable energy gradients for carrier flow control. This parameter-based design provides clear fabrication guidelines and enables precise control of carrier injection without requiring extremely tight dimensional tolerances.
3Stress or pressure
If the interface layer uses materials with larger in-plane lattice constants than the barrier layer, then compressive stress is reduced, but material selection constraints increase
Solution Approach 1:
The patent systematically varies the in-plane lattice constant parameter across the interface layer sub-layers, with at least one layer having a larger lattice constant than the barrier layer. This parameter change effectively reduces compressive stress in the quantum well structure. The approach provides a clear material selection criterion (lattice constant > barrier layer) that simplifies the choice of appropriate semiconductor materials while achieving stress reduction.
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 proposed structure improves light emission efficiency by effectively controlling electron and hole injection through quantum mechanical tunneling, minimizing electron leakage, and optimizing energy bandgap relationships to enhance the internal quantum efficiency of the light emitting device.
Implementation Method 1
effectively controlling electron and hole injection through quantum mechanical tunneling
Implementation Method 2
reduces compressive stresses
Implementation Method 3
enhances electron-hole combination probability
Data Source
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Figure 3~4
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AI summary
Disclosed herein is a light emitting device including a light emitting structure including a first conductivity-type semiconductor layer (120), a second conductivity-type semiconductor layer (150), and an active layer (130) including at least one combination of a well layer of a first composition formed of a nitride-semiconductor material having first electronic energy and a barrier layer of a second composition formed of a nitride-semiconductor material having higher electronic energy than the first electronic energy, and an interface layer (140) disposed between the second conductivity-type semiconductor layer and the active layer or between the first conductivity-type semiconductor layer and the active layer. The interface layer includes first, second and third layers having different energy bandgaps, the energy bandgaps of the first and second layers are greater than the energy bandgap of the barrier layer, and the energy bandgap of the third layer is less than the energy bandgap of the barrier layer.