Optically Pumped LED With Segmented Quantum Wells
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Solution Overview
Problem
InGaN-based light-emitting diodes that emit green light have low internal efficiency compared to those emitting UV or blue light, and increasing the number of quantum wells does not significantly improve efficiency due to uneven charge carrier distribution.
Innovation Solution
A light-emitting diode structure comprising a first semiconductor body for generating UV or blue light and a second semiconductor body with a multiple quantum well structure for re-emitting longer wavelengths, where the second body is optically pumped to achieve uniform charge distribution and enhance efficiency, with a connecting material and coupling-out structures to optimize radiation transfer and reduce thermal and spectral losses.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If the number of quantum wells is increased to improve green light generation efficiency, then the internal efficiency should increase, but the charge carrier distribution becomes uneven and efficiency gains are limited
Solution Approach 1:
The device is divided into two separate semiconductor bodies: a first semiconductor body for generating UV or blue light with high efficiency, and a second semiconductor body for re-emitting green light. This segmentation allows each body to be optimized independently, with the first body operating at high current densities without suffering from charge carrier distribution issues that would plague a single structure with many quantum wells.
Solution Approach 2:
The first semiconductor body acts as an intermediary that converts electrical energy to UV/blue light, which then serves as the pump source for the second semiconductor body. This intermediary optical conversion allows the second body to be optically pumped with uniform energy distribution, avoiding the electrical pumping limitations.
2Illumination intensity
If electrically pumped quantum wells are used to generate green light, then green light emission is achieved, but the internal efficiency remains very low compared to UV or blue LEDs
Solution Approach 1:
The patent replaces electrical pumping (mechanical/electrical system) with optical pumping in the second semiconductor body. The first semiconductor body generates UV or blue light that optically pumps the quantum wells in the second body, achieving green light emission with uniform energy distribution and avoiding the inefficiencies of direct electrical pumping at high current densities.
3Productivity
If a single semiconductor body with multiple quantum wells is used, then green light generation is attempted, but thermal management and spectral properties deteriorate
Solution Approach 1:
The thermal management function is segmented to the heat sink structure that is specifically designed for the first semiconductor body. Since the first body operates at high current densities generating UV/blue light, it has dedicated thermal management. The second body, optically pumped and operating at lower current densities, has separate thermal characteristics, allowing independent optimization of each body's thermal properties.
Solution Approach 2:
Each semiconductor body is optimized for its specific function: the first body is optimized for high-efficiency electrical-to-optical conversion with corresponding thermal management, while the second body is optimized for optical pumping and wavelength conversion. This local optimization allows each component to have the ideal properties for its specific role without compromise.
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 described light-emitting diode achieves improved efficiency in generating green light by maximizing the use of UV or blue radiation for electron-hole pair generation in the quantum well structure, offering better spectral and thermal properties and higher current densities than electrically pumped green light-emitting diodes.
Implementation Method 1
During operation of the light-emitting diode, electromagnetic radiation of a first wavelength range is generated in the active region of the first semiconductor body. The electromagnetic radiation is generated by electrically operating the active area.
Implementation Method 2
During operation of the light-emitting diode, electromagnetic radiation of the first wavelength range is absorbed in the re-emission range and electromagnetic radiation of a second wavelength range is re-emitted.
Data Source
AI summary
The invention relates to a light diode having a first semiconductor element (10) that comprises at least one active region (11) that is contacted electrically, wherein electromagnetic radiation (110) of a first wavelength region is created in the active region (11) in operation of the light diode, and a second semiconductor element (20) that is fastened on the first semiconductor element (10) to the top side (10a) of the first semiconductor element (10), wherein the second semiconductor element (20) has a re-emission region (21) having a multiple quantum well structure (213) and wherein electromagnetic radiation (110) of the first wavelength region is absorbed and electromagnetic radiation of a second wavelength region (220) is re-emitted in the re-emission region (21) in operation of the light diode, and a connection material (30) that is arranged between the first (10) and second semiconductor element (20), wherein the connection material (30) connects the first (10) and the second semiconductors (20) to one another mechanically.