Nitride Semiconductor Light Emitting Device Crystallinity
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Solution Overview
Problem
Conventional nitride semiconductor light emitting devices face issues with crystallinity, optical power, and reliability due to crystal defects and high silicon doping concentrations, which lead to increased leakage current and reduced lifespan.
Innovation Solution
A nitride semiconductor light emitting device with a first electrode contact layer in a super lattice structure of AlGaN/n-GaN or AlGaN/GaN/n-GaN is used, along with an active layer and a second nitride semiconductor layer, to enhance crystallinity and optical power, and a method for fabricating this device is employed, including forming a buffer layer and recrystallizing it at high temperature to reduce defects and improve current spreading.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If high silicon doping concentration is used to decrease contact resistance, then contact resistance is decreased, but point defects increase and active layer quality deteriorates
Solution Approach 1:
The n-GaN layer is segmented into a first sub-layer with high silicon doping for low contact resistance and a second sub-layer with low silicon doping that serves as a buffer for the active layer. This segmentation prevents high doping concentration from reaching the active layer, thus avoiding point defects while maintaining good contact properties.
Solution Approach 2:
The second sub-layer with low doping concentration acts as an intermediary between the high-doping contact region and the active layer. It mediates the transition and prevents the harmful effects of high doping concentration from propagating to the active layer, protecting the active layer quality while maintaining electrical conductivity.
2Manufacturing precision
If the n-GaN layer thickness is increased to improve crystallinity, then crystallinity is improved, but strain increases and layer breakage occurs
Solution Approach 1:
The n-GaN layer is divided into two sub-layers with different thicknesses and doping concentrations. The first sub-layer is thinner (50-200 nm) with high doping, while the second sub-layer is thicker (200-500 nm) with low doping. This segmentation allows the total thickness to be sufficient for crystallinity while distributing strain more effectively to prevent breakage.
Solution Approach 2:
By changing the doping concentration parameter across the layer thickness, the patent optimizes the balance between crystallinity and strain management. The low-doping second sub-layer provides the necessary thickness for good crystallinity while having lower strain, preventing layer breakage.
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 enhances the crystallinity and optical power of the light emitting device, stabilizes operation voltage, increases breakdown voltage, and decreases leakage current, thereby improving the reliability and efficiency of the device.
Implementation Method 1
the buffer layer 103 is formed of a GaN-based nitride or an AlN-based nitride having an amorphous phase at a low temperature. After the buffer layer 103 is formed, the n-GaN layer 105 doped with silicon at a doping concentration of 10^18/cm³ is formed at a high temperature
Data Source
AI summary
The present invention relates to a nitride semiconductor light emitting device including: a first nitride semiconductor layer having a super lattice structure of AlGaN/n-GaN or AlGaN/GaN/n-GaN; an active layer formed on the first nitride semiconductor layer to emit light; a second nitride semiconductor layer formed on the active layer; and a third nitride semiconductor layer formed on the second nitride semiconductor layer. According to the present invention, the crystallinity of the active layer is enhanced, and optical power and reliability are also enhanced.