Semiconductor Light-Emitting Element With Multilayer Reflective Film
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Solution Overview
Problem
The blue-violet LED has insufficient light-emission output, limiting the increase in light-emission output of white LEDs, as existing multilayer reflective films fail to improve reflectivity effectively for this wavelength range.
Innovation Solution
A semiconductor light-emitting element with an emission peak wavelength between 395 nm and 425 nm, featuring a substrate with a fine uneven surface and a multilayer reflective film composed of alternately stacked first and second dielectric films with specific refractive indices and film thickness variations, designed to enhance reflectivity across the 380 to 430 nm range.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If a conventional multilayer reflective film is used to increase reflectivity at specific wavelengths, then light-emission efficiency is improved, but the reflectivity improvement is insufficient for blue-violet LED wavelengths (380-430 nm)
Solution Approach 1:
The patent changes the optical parameters of the reflective film by introducing a wavelength-selective reflective film with specific optical characteristics that provide high reflectivity in the blue-violet wavelength range (380-430 nm). The film is designed with a reflectivity of 80% or more at these wavelengths, representing a parameter change from conventional films that do not effectively reflect this wavelength range.
Solution Approach 2:
The patent employs a composite structure consisting of a conventional multilayer reflective film combined with a wavelength-selective reflective film. This composite approach integrates the general light-reflecting capabilities of multilayer films with the specific wavelength-selective properties of the additional film, achieving both broad-spectrum reflectivity and targeted enhancement in the blue-violet range.
2Ease of manufacture
If the emission peak wavelength of the LED is not precisely controlled, then manufacturing flexibility increases, but the reflectivity improvement from existing reflective films decreases
Solution Approach 1:
The wavelength-selective reflective film is designed with a broad reflection band covering 380-430 nm, providing a 50 nm wavelength range where high reflectivity is maintained. This parameter design allows the system to tolerate variations in LED emission peak wavelength while maintaining effective light extraction and overall reflectivity performance.
Solution Approach 2:
The reflective system provides differentiated reflectivity characteristics across the spectrum, with enhanced local reflectivity specifically in the blue-violet range (380-430 nm) where LED emission occurs. This localized quality enhancement ensures that even with wavelength variations, the critical emission wavelengths are consistently reflected with high efficiency.
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 significantly improves light-emission efficiency and output of the semiconductor light-emitting element, even when the emission peak wavelength deviates, allowing for higher luminance and cost-effective manufacturing of high-intensity light-emitting devices.
Implementation Method 1
a multilayer reflective film composed of alternately stacked first and second dielectric films with specific refractive indices and film thickness variations, designed to enhance reflectivity across the 380 to 430 nm range
Data Source
AI summary
A semiconductor light-emitting element having an emission peak wavelength of 395 nm or more and 425 nm or less, comprises: a substrate including a first surface and a second surface, at least one surface selected from the group consisting of the first and second surfaces having an uneven region; a semiconductor layer on the first surface; and a multilayer reflective film on the second surface or the semiconductor layer, wherein the multilayer reflective film includes a structure having a plurality of first dielectric films and a plurality of second dielectric films, the first dielectric films and the second dielectric films being alternately stacked.