UV LED Substrate Segmentation for Defect Blocking
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Solution Overview
Problem
Current UV light-emitting diodes (LEDs) face challenges in achieving high external quantum efficiency due to lattice defects and material mismatch issues, which affect the performance and efficiency of UV LEDs in various applications.
Innovation Solution
A light-emitting device manufacturing method involving a substrate with protrusion and base parts, a lattice buffer layer with defect-blocking structures, and a light-emitting stack comprising n-type, active, and p-type semiconductor layers, where defect-blocking structures are used to prevent lattice defects from extending into the epitaxial growth, enhancing epitaxial quality and external quantum efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a conventional flat substrate is used for UV LED manufacturing, then the manufacturing process is simple, but lattice defects and material mismatch reduce external quantum efficiency
Solution Approach 1:
The substrate surface is segmented into protrusion parts and base parts, creating a non-uniform topography that divides the growth area into regions with different functions. The protrusion parts serve as defect-blocking structures while the base parts provide growth area, resolving the contradiction by segmenting the substrate surface into functional zones.
Solution Approach 2:
Different regions of the substrate are given different local qualities: the protrusion parts have higher height to block defects, while the base parts provide broader area for epitaxial growth. This local differentiation allows the substrate to simultaneously achieve high epitaxial quality in growth regions while maintaining structural complexity only where needed for defect blocking.
2Manufacturing precision
If lattice defects are present in the buffer layer, then the manufacturing process is simpler, but external quantum efficiency deteriorates
Solution Approach 1:
The protrusion parts are formed on the substrate before epitaxial growth begins, creating preliminary defect-blocking structures that prevent lattice defects from extending into the light-emitting stack during the growth process. This preliminary action ensures high external quantum efficiency without requiring complex post-processing steps.
Solution Approach 2:
The protrusion parts act as intermediary structures between the substrate and the epitaxial layers, blocking the propagation of lattice defects from the substrate into the light-emitting stack. This intermediary structure resolves the contradiction by filtering out defects while allowing the epitaxial growth to proceed on the base parts.
3Manufacturing precision
If the substrate surface is made flat, then manufacturing is easier, but light extraction efficiency is reduced
Solution Approach 1:
The protrusion parts are formed with curved or rounded top surfaces rather than sharp edges, which reduces stress concentration and facilitates epitaxial growth. The curved surfaces also help in directing light extraction while maintaining ease of manufacturing through standard semiconductor processing techniques.
Data Source
AI summary
The present invention discloses a light-emitting device and the manufacturing method thereof. The light-emitting device comprises: a substrate including a protrusion part and a base part; a lattice buffer layer formed on the substrate and including a first region substantially right above the protrusion part and a second region substantially right above the base part, wherein the first region includes a recess therein; a light-emitting stack formed on the lattice buffer layer and the recess; and electrodes formed on and electrically connected to the light-emitting stack.