Resonant Optical Cavity Structure for Deep UV Light Extraction
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Solution Overview
Problem
Conventional light emitting diodes (LEDs) exhibit poor light extraction efficiency due to high refractive indices and numerous optical modes, limiting the useful production of light, especially in deep ultraviolet wavelengths where material and design challenges are more pronounced.
Innovation Solution
A resonant optical cavity light emitting device is designed with a substrate, reflective layers, spacer regions, and a light emitting region configured to emit deep ultraviolet wavelengths, utilizing aluminum as a reflector and AlN or AlGaN materials to optimize the optical cavity thickness and refractive index for improved light extraction efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If conventional LED structures with high refractive index materials are used, then the device can be manufactured with standard materials, but light extraction efficiency is poor due to small escape cone and total internal reflection
Solution Approach 1:
The patent introduces vertical cavity resonance by adding the vertical dimension to the optical path. The optical cavity extends perpendicular to the substrate, creating resonant modes that enhance light extraction in the vertical direction, thereby overcoming the limitation of small escape cone in planar devices
Solution Approach 2:
The patent changes the optical parameters by introducing a resonant optical cavity with specific thickness (less than or equal to K·λ/n) and using reflective layers with specific reflectivity (>90%). These parameter changes create resonant conditions that enhance light extraction efficiency at specific wavelengths
2Loss of energy
If the optical cavity thickness is reduced to enhance resonance effect, then light extraction efficiency improves, but the device becomes more sensitive to manufacturing tolerances
Solution Approach 1:
The patent uses composite structures combining semiconductor materials (AlN, AlGaN) with metallic reflective layers (aluminum). This composite approach allows the cavity to achieve resonant enhancement while the reflective layers provide robust wavelength selectivity, reducing sensitivity to exact cavity thickness variations
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 resonant optical cavity design enhances light extraction efficiency by reducing non-propagating optical modes and increasing the overlap of propagating modes with the light emitting region, effectively addressing the limitations of existing LEDs in deep ultraviolet wavelengths.
Implementation Method 1
The optical cavity can be designed with a resonance to improve emission of a particular wavelength
Implementation Method 2
a first reflective layer, a first spacer region, a light emitting region, a second spacer region, and a second reflective layer
Implementation Method 3
In light emitting diodes (LEDs), electrons and holes injected from the p-type and n-type source regions recombine within the intrinsic region, generating light
Data Source
AI summary
Resonant optical cavity light emitting devices are disclosed, where the device includes a substrate, a first spacer region, a light emitting region, a second spacer region, and a reflector. The light emitting region is configured to emit a target emission deep ultraviolet wavelength and is positioned at a separation distance from the reflector. The reflector may be a distributed Bragg reflector. The device has an optical cavity comprising the first spacer region, the second spacer region and the light emitting region, where the optical cavity has a total thickness less than or equal to K·λ/n. K is a constant ranging from 0.25 to 10, λ is the target wavelength, and n is an effective refractive index of the optical cavity at the target wavelength.