Nitride Semiconductor Light-Emitting Element with Tunnel Junction
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Solution Overview
Problem
Existing light-emitting elements with nitride semiconductor stacked structures have high drive voltage requirements, limiting their efficiency and performance.
Innovation Solution
Incorporating a non-doped GaN layer of specific thickness between the p-type GaN and n-type GaN layers, with the n-type GaN layer doped at a higher impurity concentration than the initial n-type nitride semiconductor layer, to enhance the tunnel effect and reduce drive voltage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If a tunnel junction is formed using conventional doping methods in nitride semiconductors, then the light-emitting element can operate, but the drive voltage remains high
Solution Approach 1:
The patent changes the doping concentration parameter significantly, using high-concentration doping (1×10^19 to 1×10^21 atoms/cm³) for the n-type GaN layer and moderate-concentration doping (1×10^17 to 1×10^19 atoms/cm³) for the p-type GaN layer. This parameter optimization enables effective tunneling while maintaining low drive voltage, resolving the contradiction between energy efficiency and junction performance.
Solution Approach 2:
The patent introduces a non-doped GaN layer as an intermediary between the p-type and n-type GaN layers. This intermediate layer with thickness of 1 nm to 10 nm facilitates controlled tunneling while preventing direct high-damage contact between oppositely doped layers, thereby achieving low drive voltage without sacrificing tunnel junction reliability.
2Reliability
If the n-type GaN layer is doped at high concentration to enhance tunneling, then tunnel junction performance improves, but drive voltage increases
Solution Approach 1:
The patent optimizes the doping concentration parameter to achieve the sweet spot for tunneling: high enough (1×10^19 to 1×10^21 atoms/cm³) to enable effective tunneling and low drive voltage, but not so high as to cause excessive lattice damage and increase operational voltage. This precise parameter control resolves the contradiction between tunneling performance and drive voltage.
Solution Approach 2:
The patent performs preliminary high-concentration doping during the epitaxial growth process itself, rather than attempting post-growth doping. This preliminary action during growth achieves the desired high doping concentration with better crystal quality and less lattice damage, enabling effective tunneling without excessive drive voltage.
3Use of energy by moving object
If a non-doped GaN layer is inserted between p-type and n-type GaN layers to reduce drive voltage, then energy efficiency improves, but manufacturing precision requirements increase
Solution Approach 1:
The patent specifies a practical thickness range (1 nm to 10 nm) for the non-doped GaN layer that balances tunneling effectiveness with manufacturability. This parameter range is thin enough to enable tunneling but thick enough to be controllable with standard epitaxial growth techniques, resolving the contradiction between energy efficiency and manufacturing precision.
Solution Approach 2:
The non-doped GaN layer is formed as an intermediary step during the epitaxial growth process, allowing precise thickness control through growth time and rate parameters. This preliminary formation during growth, rather than post-processing, achieves the required precision while maintaining the low drive voltage benefit.
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 the drive voltage while maintaining or increasing the output of the light-emitting element by optimizing the tunnel junction in the semiconductor stacked structure, thereby improving the overall efficiency and performance.
Implementation Method 1
a non-doped GaN layer provided between the p-type GaN layer and the n-type GaN layer, a thickness of the non-doped GaN layer being not more than a width of a depletion layer formed by the n-type GaN layer and the p-type GaN layer
Data Source
AI summary
A light-emitting element includes: a first n-type nitride semiconductor layer; a first light-emitting layer located on the first n-type nitride semiconductor layer; a p-type GaN layer located on the first light-emitting layer; an n-type GaN layer located on the p-type GaN layer and doped with an n-type impurity at an impurity concentration higher than that of the first n-type nitride semiconductor layer; a non-doped GaN layer located between the p-type GaN layer and the n-type GaN layer, a thickness of the non-doped GaN layer being not more than a width of a depletion layer formed by the n-type and p-type GaN layers; a second n-type nitride semiconductor layer located on the n-type GaN layer and doped with an n-type impurity; a second light-emitting layer located on the second n-type nitride semiconductor layer; and a p-type nitride semiconductor layer located on the second light-emitting layer and doped with a p-type impurity.