LED Pixel Array N-Contact Trench Layout for Optical Isolation
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Solution Overview
Problem
Existing LED arrays face challenges in optical efficiency due to metal contacts with limited reflectivity, leading to optical absorption and potential damage during substrate removal, which affects long-term reliability and optical performance.
Innovation Solution
The implementation of a dielectric layer between semiconductor layers and electrically conductive material in the trenches of LED devices, with n-contact formation at the mesa bottom, reduces optical absorption and enhances optical isolation between pixels.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If metal side-contacts are extended deep into the trench to ensure low sheet and contact resistance, then electrical conductivity is improved, but optical absorption increases due to limited metal reflectivity
Solution Approach 1:
A dielectric layer is introduced as an intermediary between the metal contact and the semiconductor layers. This dielectric layer has high optical reflectivity and acts as an optical mirror, reflecting light away from the metal contact while allowing the metal to maintain its electrical function. The dielectric layer thus mediates between the electrical conductivity requirement and the optical efficiency requirement.
Solution Approach 2:
The contact structure becomes a composite system combining metal (for electrical conductivity) and dielectric material (for optical reflection). This composite structure allows both functions to coexist: the metal provides low contact resistance while the dielectric layer provides high optical reflectivity, eliminating the trade-off between electrical and optical performance.
2Reliability
If metal contacts are used to form the cathode contact, then electrical conductivity is achieved, but optical efficiency is limited by severe absorption in the cavity
Solution Approach 1:
The dielectric layer serves as an optical intermediary that reflects light before it can be absorbed by the metal contact. By placing this high-reflectivity dielectric layer between the light path and the metal contact, the system achieves both electrical conductivity through the metal and optical efficiency through the dielectric reflection.
3Use of energy by moving object
If the substrate is removed by laser lift-off process to enhance light extraction, then optical performance is improved, but the side contacts are damaged and long-term reliability is compromised
Solution Approach 1:
The dielectric layer acts as a protective intermediary between the laser beam and the metal contact during the laser lift-off process. Since the dielectric layer absorbs the laser energy and protects underlying structures, it shields the metal contact from laser-induced damage while still allowing the substrate to be removed for light extraction enhancement.
4Reliability
If deep side contacts are used to optically separate each LED pixel, then optical isolation is improved, but optical absorption increases due to limited metal reflectivity
Solution Approach 1:
The pixel separation structure becomes a composite of dielectric and metal materials. The dielectric layer provides high optical reflectivity for pixel isolation, while the metal contact provides electrical functionality. This composite approach eliminates the need for deep metal trenches and reduces optical absorption while maintaining optical isolation.
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 design significantly improves optical efficacy by minimizing optical absorption and enhancing optical isolation, resulting in improved LED array performance.
Implementation Method 1
the dielectric layer optically isolates the trench
Data Source
AI summary
Arrays of light emitting diode (LED) devices, each LED device includes a mesa having a top surface and at least one sidewall defining a trench having a bottom surface. The mesa comprises semiconductor layers including an N-type layer, an active layer, and a P-type layer, and an electrically conductive material fills the trench. A dielectric layer lines the trench such that the dielectric layer optically isolates the electrically conductive material the trench.