N-type Nitride Semiconductor Layer with Modulation-Doped Intermediate Structure
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Solution Overview
Problem
Nitride semiconductors grown on heterogeneous substrates face challenges such as high defect density, stress, and strain due to lattice parameter differences, leading to reduced luminous efficiency and increased forward voltage in light emitting diodes, as well as inefficient current spreading.
Innovation Solution
A light emitting diode structure is developed with an n-type nitride semiconductor layer that includes a modulation-doped layer with varying doping concentrations and a superlattice structure, along with intermediate layers to enhance crystallinity and electron injection efficiency, allowing for uniform current spreading and improved luminous efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If nitride semiconductor is grown on heterogeneous substrate, then fabrication is enabled, but defect density increases and crystallinity deteriorates
Solution Approach 1:
The patent introduces an intermediate layer between the heterogeneous substrate and the nitride semiconductor layer. This intermediate layer acts as a mediator that reduces lattice mismatch and thermal expansion differences, thereby lowering defect density and improving crystallinity while still enabling fabrication on heterogeneous substrates.
Solution Approach 2:
The patent segments the semiconductor structure into multiple distinct layers with different compositions and properties. By dividing the structure into substrate, intermediate layer, and nitride semiconductor layer, each component can be optimized independently to resolve the contradiction between manufacturability and crystallinity.
2Reliability
If doping concentration is increased to improve electron injection, then electron injection efficiency improves, but current spreading becomes non-uniform
Solution Approach 1:
The patent applies local quality by creating regions with different doping concentrations within the nitride semiconductor layer. High doping concentration regions are placed where electron injection is needed, while lower doping concentration regions are placed where uniform current spreading is required, thereby resolving the contradiction between injection efficiency and uniformity.
Solution Approach 2:
The patent changes the doping concentration parameter spatially within the nitride semiconductor layer. By varying the doping concentration from region to region, the patent optimizes both electron injection efficiency in specific areas and current spreading uniformity in other areas, resolving the contradiction between these two requirements.
Data Source
AI summary
A light emitting diode includes: an n-type nitride semiconductor layer; an active layer over the n-type nitride semiconductor layer; and a p-type nitride semiconductor layer over the active layer. The n-type nitride semiconductor layer includes: an n-type nitride layer; a first intermediate layer over the n-type nitride layer; an n-type modulation-doped layer over the first intermediate layer. The light emitting diodes includes a second intermediate layer over the n-type modulation-doped layer. The second intermediate layer includes a sub-layer having a higher n-type doping concentration that an n-type doping concentration of the n-type modulation-doped layer.