Semi-Polar Nitride Light Emitting Device on M-Plane Sapphire
Solution Overview
Problem
The manufacturing of nitride semiconductor light emitting devices using c-plane sapphire substrates results in reduced luminous efficiency due to internal electric fields and piezoelectric polarization, making it difficult to achieve high-quality semi-polar nitride thin films.
Innovation Solution
A method involving the growth of semi-polar (11-22) plane nitride thin films on an m-plane sapphire substrate, where the substrate is nitrided within an optimum temperature range and a high-temperature buffer layer is formed to enhance crystallinity, allowing for the formation of a light emitting structure with increased efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If c-plane sapphire substrate is used to grow nitride thin films, then the manufacturing process is simple and well-established, but internal electric fields and piezoelectric polarization reduce luminous efficiency
Solution Approach 1:
The patent changes the crystallographic orientation parameter of the sapphire substrate from c-plane to m-plane, and changes the growth plane from c-plane to semi-polar (11-22) plane. This parameter change eliminates the polarity-induced internal electric field and piezoelectric polarization effects, thereby resolving the luminous efficiency problem while maintaining manufacturing feasibility
Solution Approach 2:
Instead of attempting to improve performance on the conventional c-plane substrate, the patent inverts the approach by using the non-conventional m-plane substrate with semi-polar orientation. This inversion fundamentally changes the crystal structure properties to eliminate the harmful polarization effects that plague conventional devices
2Ease of manufacture
If c-plane sapphire substrate is used, then existing manufacturing techniques can be applied, but piezoelectric polarization reduces luminous wavelength and device performance
Solution Approach 1:
By changing the substrate orientation parameter from c-plane to m-plane and the film growth plane to semi-polar (11-22), the patent eliminates piezoelectric polarization effects. This allows precise control of luminous wavelength without the degrading influence of polarization-induced wavelength shifts
3Ease of manufacture
If semi-polar nitride thin film is grown on c-plane sapphire substrate using existing techniques, then the process is feasible, but high-quality crystallinity cannot be achieved
Solution Approach 1:
The patent changes the substrate orientation to m-plane and the growth plane to semi-polar (11-22), which fundamentally improves crystallinity quality. The non-polar m-plane substrate provides a better lattice match and reduces dislocation density, enabling high-quality semi-polar film growth that cannot be achieved on c-plane substrates
Solution Approach 2:
The patent introduces a buffer layer as an intermediary between the m-plane sapphire substrate and the semi-polar nitride thin film. This buffer layer facilitates epitaxial growth and improves the interface quality, enabling high-quality crystallinity to be achieved while maintaining process feasibility
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 increases the luminous efficiency of the light emitting device by preventing internal electric fields and improving crystallinity, enabling the production of high-quality semi-polar nitride thin films that enhance the reliability and wavelength of the device.
Implementation Method 1
nitriding a surface of an m-plane sapphire substrate
Implementation Method 2
introducing the m-plane sapphire substrate into an MOCVD chamber; and supplying ammonia (NH3) gas into the MOCVD chamber
Implementation Method 3
forming a high-temperature buffer layer on the m-plane sapphire substrate; increasing the temperature inside the MOCVD chamber to a temperature within a range of 900 to 1100° C. to perform epitaxial growth
Implementation Method 4
depositing a semi-polar (11-22) plane nitride thin film on the high-temperature buffer layer
Data Source
AI summary
There is provided a method of manufacturing a nitride semiconductor light emitting device. A method of manufacturing a nitride semiconductor light emitting device according to an aspect of the invention may include: nitriding a surface of an m-plane sapphire substrate; forming a high-temperature buffer layer on the m-plane sapphire substrate; depositing a semi-polar (11-22) plane nitride thin film on the high-temperature buffer layer; and forming a light emitting structure including a first nitride semiconductor layer, an active layer, and a second nitride semiconductor layer on the semi-polar (11-22) plane nitride thin film.