Nitride Semiconductor Light Emitting Device Current Diffusion Layer
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Solution Overview
Problem
Nitride semiconductor light emitting devices face limitations in reducing dislocation spread on substrates and achieving uniform carrier supply, which affects their performance and reliability.
Innovation Solution
The implementation of a current diffusion layer with a conductive material like indium tin oxide (ITO) and specific doping strategies in nitride semiconductor light emitting devices, along with a buffer layer, to reduce dislocation propagation and enhance carrier concentration and electrostatic discharge properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a buffer layer is formed on the sapphire substrate to reduce lattice constant difference, then dislocation spreading to the n-GaN layer is reduced, but the dislocation reduction is limited and cannot be fully eliminated
Solution Approach 1:
The patent segments the semiconductor layer structure into multiple distinct functional layers: buffer layer, first conductive lower semiconductor layer, current diffusion layer, first conductive upper semiconductor layer, active layer, and second conductive semiconductor layer. Each layer is optimized to address specific issues, with the current diffusion layer specifically designed to block dislocation propagation while managing carrier distribution.
Solution Approach 2:
The current diffusion layer acts as an intermediary between the lower and upper conductive semiconductor layers. It serves multiple functions: blocking dislocation propagation from the substrate, uniformly distributing carriers, and reducing contact resistance. This intermediary layer resolves the contradiction by providing a specialized functional barrier without requiring complete structural redesign.
2Power
If carriers are supplied to the active layer, then light emission occurs, but non-uniform carrier distribution reduces device efficiency
Solution Approach 1:
The current diffusion layer serves as an intermediary that uniformly distributes carriers before they reach the active layer. It has higher conductivity than the surrounding semiconductor layers, creating a spreading effect that ensures even carrier distribution across the active region, thereby improving both efficiency and reliability.
Solution Approach 2:
The patent changes the electrical conductivity parameter of the current diffusion layer to be higher than the adjacent semiconductor layers. This parameter change enables the layer to act as a carrier redistribution zone, transforming the carrier distribution from non-uniform to uniform, which directly addresses the contradiction between power efficiency and reliability.
3Power
If the contact resistance between electrode and semiconductor layer is reduced, then device performance improves, but dislocation propagation from substrate continues to affect performance
Solution Approach 1:
The patent introduces a dedicated current diffusion layer as a separate segment between the lower conductive semiconductor layer and the upper conductive semiconductor layer. This segmentation allows the current diffusion layer to specifically address dislocation blocking while the adjacent layers handle conductivity, resolving the contradiction by separating these two functions into distinct structural elements.
Solution Approach 2:
The current diffusion layer can be formed from composite structures or materials with tailored properties that simultaneously provide high conductivity and dislocation blocking capability. The layer combines electrical conductivity with mechanical/dislocation barrier properties, creating a composite functional element that addresses both requirements.
4Ease of manufacture
If the device structure is simplified, then manufacturing is easier, but carrier distribution uniformity and dislocation control are compromised
Solution Approach 1:
The current diffusion layer is designed with multi-functionality, simultaneously performing three key functions: blocking dislocation propagation from the substrate, uniformly distributing carriers across the active layer, and reducing contact resistance. This multi-functionality allows a single layer to address multiple reliability issues without proportionally increasing structural complexity, making the enhanced design more manufacturable.
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
This approach effectively reduces dislocation spread, increases carrier concentration, lowers operating voltage, and enhances the reliability and power efficiency of nitride semiconductor light emitting devices while improving electrostatic discharge characteristics.
Implementation Method 1
a current diffusion layer on the first conductive lower semiconductor layer
Implementation Method 2
because the sapphire substrate and the n-GaN layer have different lattice constants, dislocation of the boundary surfaces of the sapphire substrate and the n-GaN layer occurs. In order to reduce the difference of the lattice constants between the sapphire substrate and the n-GaN layer, a buffer layer is formed on the sapphire substrate
Data Source
AI summary
A light emitting device and a method of manufacturing the same are provided. The light emitting device comprises a first conductive type lower semiconductor layer, a current diffusion layer, a first conductive type upper semiconductor layer, an active layer, and a second conductive type semiconductor layer. The current diffusion layer is formed on the first conductive type lower semiconductor layer. The first conductive type upper semiconductor layer is formed on the current diffusion layer. The active layer is formed on the first conductive type upper semiconductor layer. The second conductive type semiconductor layer is formed on the active layer.