Multiple Quantum Well Light Emitting Element Carrier Overflow Control
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Solution Overview
Problem
Semiconductor light emitting elements, such as LEDs, experience reduced light emission efficiency and output at high temperatures due to carrier overflow, trapping, and reduced carrier injection efficiency, necessitating a solution to maintain high efficiency and temperature characteristics.
Innovation Solution
A semiconductor light emitting element with a multiple quantum well (MQW) structure incorporating a super lattice structure layer, an electron injection control layer, and an MQW light emitting layer, where the electron injection control layer decelerates electrons to improve injection efficiency and reduce overflow, comprising repeatedly-formed barrier and quantum well layers with specific band gap and thickness configurations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If the operating temperature of a semiconductor light emitting element is increased, then the light emission output is reduced due to carrier overflow and reduced recombination efficiency
Solution Approach 1:
The light emitting layer is divided into multiple quantum well structures with different band gaps, creating distinct regions for carrier injection and light emission. This segmentation allows electrons to be injected into lower band gap regions while holes remain in higher band gap regions, preventing carrier overflow even at elevated temperatures.
Solution Approach 2:
Different regions of the light emitting layer are assigned different band gap characteristics. The first quantum well layer has a smaller band gap optimized for electron injection, while the second quantum well layer has a larger band gap optimized for light emission. This local differentiation of properties enables temperature-resistant operation.
2Temperature
If the operating temperature is increased, then the carrier injection efficiency is reduced due to increased carrier trapping and overflow
Solution Approach 1:
The first quantum well layer with smaller band gap is positioned to receive electrons first, before they can overflow into unwanted regions. This preliminary capture of carriers ensures efficient injection even at high temperatures, preventing carrier loss before the main light emission process occurs.
3Device complexity
If a simple single-layer light emitting structure is used, then the device complexity is low, but the light emission efficiency and temperature characteristics are insufficient
Solution Approach 1:
The light emitting layer combines multiple quantum well layers with different compositions and band gaps within a single semiconductor structure. This composite approach integrates materials with different properties to achieve both high light emission efficiency and excellent temperature characteristics while maintaining a unified device architecture.
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 suppresses carrier overflow, enhances carrier injection efficiency, and maintains high light emission efficiency and temperature characteristics even at elevated temperatures, as demonstrated by improved light output and reduced roll-off ratios at 70°C compared to room temperature.
Implementation Method 1
an MQW light emitting layer formed on the second control layer and including repeatedly-formed barrier layers and quantum well layers
Implementation Method 2
a reduction in recombination efficiency between electrons and holes due to the overflow of carriers
Implementation Method 3
a semiconductor light emitting element having a light emitting layer with a multiple quantum well (MQW) structure
Data Source
AI summary
A semiconductor light emitting element includes: an n-type semiconductor layer; a super lattice structure layer formed on the n-type semiconductor layer and including repeatedly-formed first semiconductor layers and second semiconductor layers having a composition with a band gap greater than that of the first semiconductor layer; an electron injection control layer including a first control layer formed on the second semiconductor layer of super lattice structure layer and a second control layer formed on the first control layer; and an MQW light emitting layer formed on the second control layer and including repeatedly-formed barrier layers and quantum well layers. The first control layer has a composition with a band gap smaller than that of the second semiconductor layer of super lattice structure layer. The second control layer has a composition and a thickness same as or smaller than those of the quantum well layer of the MQW light emitting layer.