Micro-LED Array With Monolayer Active Layer for High Modulation Bandwidth
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Solution Overview
Problem
Existing LEDs and phosphor-converted LEDs (pcLEDs) face limitations in achieving high modulation bandwidth for data transmission and illumination applications, particularly when driven at lower current densities to avoid high power consumption.
Innovation Solution
The development of a high-speed micro-LED array with thin active layers (0.1-1 nm thick) and doped semiconductor layers, enabling small-signal bandwidths greater than 0.10 GHz, even at current densities below 2000 A/cm², and optionally incorporating wavelength-converting elements for enhanced light emission.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If conventional LED structures are used, then device simplicity is maintained, but modulation bandwidth is limited and cannot achieve high-speed data transmission
Solution Approach 1:
The LED device is divided into multiple functional layers including a thin active layer (0.1-1 nm thick) separated from the semiconductor layers by tunnel barriers. This segmentation allows the active layer to be optimized for high-speed recombination while the doped semiconductor layers provide carrier injection, achieving high modulation bandwidth through the thin active region where carrier recombination occurs rapidly.
Solution Approach 2:
Different regions of the device have specialized properties: the active layer is kept extremely thin (0.1-1 nm) to enable fast carrier recombination and high modulation bandwidth, while the semiconductor layers are doped to provide efficient carrier injection. This local optimization of thickness and doping in different regions allows the device to achieve high-speed performance without compromising overall functionality.
2Speed
If high current density is applied to increase modulation bandwidth, then bandwidth improves, but power consumption increases excessively
Solution Approach 1:
The device achieves high modulation bandwidth by changing the physical parameter of active layer thickness to 0.1-1 nm, which enables fast carrier recombination at lower current densities. Additionally, doped semiconductor layers are introduced to improve carrier injection efficiency, allowing the device to achieve bandwidths greater than 0.10 GHz at current densities below 2000 A/cm², significantly reducing power consumption compared to conventional LEDs.
3Speed
If thicker active layers are used, then manufacturing is easier, but modulation bandwidth decreases due to slower carrier recombination
Solution Approach 1:
The active layer thickness is reduced to an extreme parameter range of 0.1-1 nm to achieve fast carrier recombination and high modulation bandwidth. This extreme thinning requires precise manufacturing control, but the use of doped semiconductor layers with tunnel barriers facilitates the formation of such thin layers through controlled growth processes, making the manufacturing of ultra-thin active layers feasible.
4Speed
If conventional phosphor conversion is used, then wavelength conversion is achieved, but modulation bandwidth is limited by phosphor emission lifetime
Solution Approach 1:
When wavelength conversion is required, phosphor layers are introduced as intermediary elements that convert the wavelength of light from the LED while maintaining the high-speed modulation capability. The thin active layer design ensures that carrier recombination occurs rapidly before phosphor conversion, allowing the LED to modulate at high speeds even when followed by phosphor conversion, thus preserving bandwidth while adding wavelength conversion functionality.
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 achieves high modulation bandwidth and efficient light emission, allowing for data transmission rates of at least 100 MHz to 1 GHz without requiring excessive current density, suitable for adaptive illumination and display technologies.
Implementation Method 1
Each LED of the array includes first and second doped semiconductor layers and an active layer therebetween so that the LED is arranged for emitting light at a nominal emission vacuum wavelength λ0 resulting from charge carrier recombination at the active layer
Implementation Method 2
Each LED of the array includes first and second doped semiconductor layers and an active layer therebetween
Data Source
AI summary
An inventive light-emitting array includes multiple semiconductor light-emitting diodes (LEDs). Each LED of the array includes first and second doped semiconductor layers and an active layer them, and emits light at a nominal emission vacuum wavelength λ0 resulting from charge carrier recombination at the active layer. The active layer differs in chemical composition from the first and second semiconductor layers and is between 0.1 nm thick and 1 nm thick. Each LED exhibits a small-signal bandwidth greater than 0.10 GHZ, in some instances at a nonzero current density less than 2000 A/cm2. In some instances the doped semiconductor layers can be p-doped and n-doped GaN layers, and the active layer can be a monolayer of a III-nitride compound, e.g., InGaN.