LED Carrier Injection Layer Work Function Engineering
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Solution Overview
Problem
Current light emitting diodes (LEDs) face challenges in achieving high current injection efficiency due to high contact resistance between p-type semiconductor layers and electrodes, limiting their light extraction and quantum efficiency.
Innovation Solution
Incorporating a hole injection layer with a critical thickness between the p-type semiconductor layer and the electrode, and a carrier injection layer with a high work function, specifically formed with a metal oxide, to increase the work function difference and enhance hole injection efficiency, thereby improving current injection and light emission efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional LED structure without additional injection layers is used, then the device complexity is low, but the current injection efficiency is limited due to high contact resistance
Solution Approach 1:
A hole injection layer is introduced as an intermediary between the p-type semiconductor layer and the electrode. This layer has a work function specifically designed to be higher than both the p-type semiconductor layer and the electrode, creating a favorable work function gradient that enhances hole injection efficiency while managing contact resistance
Solution Approach 2:
The work function parameter is strategically modified by introducing the hole injection layer with a higher work function than the adjacent layers. This parameter change creates an optimized work function difference that directly addresses the contact resistance issue and improves current injection efficiency
2Reliability
If the work function difference between the p-type semiconductor layer and electrode is increased, then hole injection efficiency improves, but the manufacturing precision requirements increase
Solution Approach 1:
The work function is used as a key control parameter, with the hole injection layer designed to have a work function higher than both the p-type semiconductor layer and the electrode. This parameter-based approach provides a clear design criterion that guides material selection and layer design
Solution Approach 2:
The hole injection layer is designed with specific local properties - a work function that is locally higher than the adjacent layers. This localized quality enhancement at the critical interface region optimizes hole injection without requiring precision control throughout the entire device structure
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 insertion of these layers increases hole injection efficiency, leading to improved electron-hole recombination and overall light emission efficiency of the LED chip, enhancing its quantum efficiency and light output.
Implementation Method 1
a carrier injection layer with a high work function, specifically formed with a metal oxide, to increase the work function difference and enhance hole injection efficiency
Data Source
AI summary
A light emitting device (LED), an LED package, and a lighting system including the LED package are provided. The light emitting device (LED) may include a light emitting structure, a carrier injection layer, and an electrode layer. The light emitting structure may include a first conductive semiconductor layer, an active layer, and a second conductive semiconductor layer. The carrier injection layer may be positioned over the light emitting structure, and the electrode layer may be positioned over the carrier injection layer.