Nitride Semiconductor Light Emitting Device with High-Concentration Doped Layer
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Solution Overview
Problem
Current nitride semiconductor structures and light emitting diodes (LEDs) face low light-extraction efficiency due to total internal reflection and high resistance in the p-type GaN layer, leading to restricted light emission and uneven current spreading, which limits their light emitting efficiency.
Innovation Solution
A nitride semiconductor structure with a second type doped semiconductor layer having a high dopant concentration (>5×10^19 cm^-3) and thickness (<30 nm) is introduced, along with a hole supply layer and carrier blocking layers to enhance electron-hole recombination and current spreading, improving light extraction and emitting efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If surface treatment is performed on p-type GaN layer to reduce total internal reflection, then light-extraction efficiency is improved, but the improvement is limited because only exposed p-type GaN can be treated
Solution Approach 1:
Instead of treating the p-type GaN layer on the surface, the patent inverts the approach by treating the n-type GaN layer on the substrate surface. A rough structure is formed on the n-type GaN layer, and the substrate is separated from this treated layer, allowing the rough structure to face outward for enhanced light extraction. This inversion enables treatment of a larger effective surface area.
Solution Approach 2:
The patent separates the n-type GaN layer from the substrate in the vertical dimension, allowing the rough structure formed on the n-type GaN layer to face the external environment rather than being confined within the device. This dimensional reconfiguration enables light extraction from what was previously an internal substrate interface.
2Loss of energy
If n-type GaN layer is separated from substrate and rough structure is formed, then light-extraction efficiency is improved, but manufacturing complexity increases and heat dissipation deteriorates
Solution Approach 1:
The rough structure is formed on the n-type GaN layer before the p-type GaN layer and other device components are deposited. This preliminary formation of the light-extraction structure simplifies the overall manufacturing process by avoiding post-assembly modifications and integrating the optical enhancement into the epitaxial growth sequence.
3Reliability
If dopant concentration in p-type GaN layer is increased, then electrical conductivity is improved, but manufacturing difficulty increases due to process limitations
Solution Approach 1:
The patent changes the dopant concentration parameter in the p-type GaN layer to greater than 5×10^19 atoms/cm³, exceeding conventional doping levels. This parameter change is achieved through optimized epitaxial growth conditions, demonstrating that high-concentration doping is manufacturable with appropriate process control.
4Illumination intensity
If current flows from metal electrodes to GaN semiconductor layer, then light emission occurs, but current spreading is uneven resulting in confined lighting area
Solution Approach 1:
The patent changes the dopant concentration parameter in the p-type GaN layer to greater than 5×10^19 atoms/cm³, which significantly reduces electrical resistance. This parameter change enables more uniform current distribution across the semiconductor layer, expanding the effective lighting area beyond the electrode boundaries.
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 proposed structure significantly increases light-extraction efficiency and achieves better current spreading, resulting in enhanced light emitting efficiency by increasing the electron-hole recombination rate and reducing resistance in the semiconductor layer.
Implementation Method 1
Due to total internal reflection of GaN and air, light emitting from LED is restricted inside the LED and the light-extraction rate is quite low
Implementation Method 2
the concentration of the dopant in the p-type GaN layer is unable to be increased effectively so that the resistance of the p-type GaN layer is quite large
Implementation Method 3
electrons and holes are respectively injected from the n-type semiconductor layer and the p-type semiconductor layer to be combined with each other in the well layers and photons are emitted
Data Source
AI summary
A nitride semiconductor structure and a semiconductor light emitting device are revealed. The semiconductor light emitting device includes a substrate disposed with a first type doped semiconductor layer and a second type doped semiconductor layer. A light emitting layer is disposed between the first type doped semiconductor layer and the second type doped semiconductor layer. The second type doped semiconductor layer is doped with a second type dopant at a concentration larger than 5×1019 cm−3 while a thickness of the second type doped semiconductor layer is smaller than 30 nm. Thereby the semiconductor light emitting device provides a better light emitting efficiency.