P-Type Layer Thickness Tuning for Low-Loss Optoelectronic Heterostructures
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Solution Overview
Problem
Optoelectronic devices, such as LEDs and laser diodes, face challenges in reducing absorption losses and enhancing light output without increasing operating voltage, particularly due to internal reflection and interference issues in their heterostructures.
Innovation Solution
The heterostructure design includes a p-type layer stack with a thickness configured for constructive interference, featuring an electron blocking layer, a p-type interlayer, and a reflective p-type contact, which promotes the extraction of light by aligning the phases of emitted and reflected radiation, thereby reducing optical losses and enhancing output.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If the heterostructure uses conventional layer thicknesses, then the device structure is simple, but optical losses occur due to destructive interference between emitted and reflected light
Solution Approach 1:
The patent applies parameter changes by precisely controlling the thickness of the p-type layer stack to satisfy the constructive interference condition: thickness = (m * λ) / (2 * n_eff), where m is an integer, λ is the emission wavelength, and n_eff is the effective refractive index. This parameter optimization transforms the optical path difference to achieve constructive interference, converting harmful destructive interference into beneficial constructive interference without changing the basic heterostructure design
Solution Approach 2:
The patent converts the harmful effect of internal reflection and destructive interference into a beneficial effect by introducing a reflective contact that, when combined with properly tuned layer thickness, creates constructive interference. The reflected light that would normally cause losses is now harnessed to enhance light extraction efficiency, turning a harmful factor into a useful one
2Productivity
If the p-type layer thickness is increased to enhance light extraction, then light output improves, but absorption losses increase in the thicker layers
Solution Approach 1:
The patent optimizes the thickness parameter of the p-type layer stack to a specific value that satisfies the constructive interference condition. This optimized thickness simultaneously achieves two goals: it enhances light extraction by promoting constructive interference while limiting the absorption path length to prevent excessive absorption losses, thus resolving the trade-off between light output and absorption loss
3Reliability
If the heterostructure is designed without considering interference effects, then manufacturing is easier, but quantum efficiency is reduced due to internal reflection
Solution Approach 1:
The patent incorporates interference effect considerations into the design phase by calculating and setting the p-type layer stack thickness to satisfy the constructive interference condition. This design-stage parameter optimization ensures high quantum efficiency is achieved while the fabrication process itself remains unchanged, thus improving quantum efficiency without complicating manufacturing
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 effectively reduces absorption losses and enhances the light output of optoelectronic devices without increasing the operating voltage, improving their reliability and quantum efficiency.
Implementation Method 1
a thickness of the set of p-type layers is configured to promote constructive interference between light reflected from the reflective structure and light emitted from a topmost quantum well of the active region
Implementation Method 2
a reflective structure located adjacent to the set of p-type layers, wherein a thickness of the set of p-type layers is configured to promote constructive interference between light reflected from the reflective structure
Data Source
AI summary
A heterostructure with reduced optical losses is disclosed. The heterostructure includes a set of n-type layers; an active region that generates radiation at a peak emitted wavelength; and a set of p-type layers located adjacent to the active region. A reflective structure can be located adjacent to the set of p-type layers. A thickness of the set of p-type layers can be configured to promote constructive interference of the reflected radiation with radiation emitted by the active region in a direction toward the set of n-type layers.