Light Emitting Device Structure With Field Oxide Wells
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional solid-state light emitting devices face issues with edge breakdown and propagation breakdown under high electric fields, leading to reduced efficiency and reliability, particularly in large area emitter structures.
Innovation Solution
The introduction of device wells defined by thick field oxide regions, with contacts placed over these regions to confine current injection and reduce electric field crowding, and the use of a substantially planar emitter layer structure with tapered field oxide sidewalls to minimize non-uniformities and discontinuities.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single relatively thick active layer is used, then the device structure is simple, but the luminous efficacy and excitation efficiency are poor
Solution Approach 1:
The single thick active layer is segmented into multiple thin active layers separated by drift layers. Each thin active layer has improved excitation efficiency, and the multiple layers work together to achieve high luminous efficacy while maintaining a manageable device structure.
Solution Approach 2:
The device structure transitions from a single-layer planar configuration to a multilayer stacked configuration. This dimensional organization in the vertical direction allows each layer to be optimized for its specific function, improving overall device performance.
2Illumination intensity
If high electric fields are applied to increase brightness, then light emission intensity improves, but edge breakdown and propagation breakdown occur
Solution Approach 1:
The device is segmented into multiple small pixel structures separated by isolation oxide regions. This segmentation confines electrical breakdown to individual pixels, preventing propagation breakdown across the entire device, thereby maintaining reliability at high brightness levels.
Solution Approach 2:
Isolation oxide regions are introduced as intermediary elements between active pixels. These oxide regions act as electrical insulators that prevent breakdown propagation while allowing optical communication between pixels, thus maintaining device reliability during high-field operation.
3Reliability
If device wells are defined by thick field oxide regions, then current injection is confined and breakdown is reduced, but the emitter layer structure exhibits non-uniformities and discontinuities
Solution Approach 1:
A planarization layer is deposited beforehand to create a flat surface for the emitter layer structure. This preliminary action compensates for the non-planar topography created by thick field oxide regions, ensuring uniform layer deposition and eliminating discontinuities.
Solution Approach 2:
A planarization layer is introduced as an intermediary between the non-planar field oxide regions and the emitter layer structure. This intermediary layer provides a flat deposition surface, ensuring manufacturing precision while maintaining the breakdown-resistant device well structure.
4Loss of energy
If multiple thin active layers are used, then excitation efficiency and luminous efficacy improve, but the device structure becomes more complex
Solution Approach 1:
The emitter layer structure is segmented into repeating units of thin active layers and drift layers. This systematic segmentation improves excitation efficiency in each unit while creating a modular structure that, although complex, follows a predictable pattern for fabrication.
Solution Approach 2:
The thickness parameters of active layers and drift layers are precisely controlled and optimized. By changing these dimensional parameters, high excitation efficiency is achieved in thin layers while the overall device complexity is managed through parameter standardization.
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 enhances efficiency, reduces deleterious breakdown effects, and improves the reliability and uniformity of light emission, allowing for higher brightness and longer device lifetime.
Implementation Method 1
contacts and interconnects are provided over the thick field oxide regions. Thus, device wells are laterally isolated, current injection is effectively confined to the device wells, and placement of contacts over the field oxide, adjacent the device well, reduces electric field crowding
Implementation Method 2
an active layer containing luminescent centres for light emission at a characteristic wavelength... electrons can be injected into the active layer... to excite light emission
Implementation Method 3
the use of a substantially planar emitter layer structure with tapered field oxide sidewalls to minimize non-uniformities and discontinuities
Data Source
AI summary
A light emitting device structure, wherein the emitter layer structure comprises one or more device wells defined by thick field oxide regions, and a method of fabrication thereof are provided. Preferably, by defining device well regions after depositing the emitter layer structure, emitter layer structures with reduced topography may be provided, facilitating processing and improving layer to layer uniformity. The method is particularly applicable to multilayer emitter layer structures, e.g. comprising a layer stack of active layer/drift layer pairs. Preferably, active layers comprise a rare earth oxide, or rare earth doped dielectric such as silicon dioxide, silicon nitride, or silicon oxynitride, and respective drift layers comprise a suitable dielectric, preferably silicon dioxide, of an appropriate thickness to control excitation energy. Pixellated light emitting structures, or large area, high brightness emitter layer structures, e.g. for solid-state lighting applications, may therefore be provided with improved process flexibility and reliability.