GeSn Nanobeam LED for On-Chip Optical Interconnects
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Solution Overview
Problem
Existing optical devices, such as communication chips, often rely on complex laser light sources or bulk LEDs, which are inefficient and costly, necessitating a simpler and more efficient light source for applications where laser capabilities are not required.
Innovation Solution
A nanobeam LED structure with a semiconductor base, featuring a central germanium-tin layer and wing extensions, integrated into a rib-channel waveguide with a 1D photonic crystal lattice, enabling efficient light transmission and modulation up to GHz rates.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If laser light sources are used, then light transmission capability is improved, but device complexity increases
Solution Approach 1:
The patent replaces expensive, complex laser sources with simpler, shorter-lived LED light sources. The GeSn nanobeam LED provides sufficient light transmission capability for communication applications without requiring the complex resonant cavity and gain medium structures of lasers, thereby reducing device complexity while maintaining adequate performance.
Solution Approach 2:
The patent changes the material parameters by using germanium-tin (GeSn) semiconductor layers with specific tin compositions (10-30%) to achieve direct bandgap properties. This material parameter change enables the LED to emit light efficiently at telecom wavelengths (1.5-2.0 μm) without requiring laser-level structural complexity.
2Device complexity
If bulk LED devices are used, then device complexity is reduced, but light transmission efficiency deteriorates
Solution Approach 1:
The patent segments the bulk LED structure into a nanoscale beam configuration. The GeSn nanobeam has dimensions of approximately 200-500 nm in width and 1-10 μm in length, creating a one-dimensional waveguide structure that confines and directs light transmission. This segmentation transforms the inefficient bulk emission into directional, efficient light transmission while maintaining structural simplicity.
Solution Approach 2:
The patent transitions from three-dimensional bulk LED emission to one-dimensional nanobeam transmission. The nanobeam confines carriers and photons in the transverse dimensions while allowing transport along the longitudinal dimension, achieving efficient directional light transmission without the complexity of multi-layer bulk LED structures.
3Illumination intensity
If nanobeam structure is implemented, then light transmission efficiency is improved, but manufacturing precision requirements increase
Solution Approach 1:
The patent extracts the light-emitting function from the bulk semiconductor and concentrates it into a nanoscale GeSn beam. By removing the surrounding bulk material and focusing the active region into a one-dimensional nanobeam, the structure achieves high light transmission efficiency while the fabrication processes (MBE, MOCVD, lithography) remain within existing manufacturing capabilities despite the precision requirements.
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 nanobeam LED structure provides a technically simpler, efficient light source with increased modulation speed and reduced bulk spontaneous recombination time, suitable for on-chip applications like fiber communications and opto-electronic computing, achieving adequate signal-to-noise ratios and feasible multi-spectral arrays.
Implementation Method 1
An electrical circuit is connected between the first and second metal contacts and supplies an electrical signal that energizes the middle section of the nanobeam to emit light
Implementation Method 2
transmit light down the left section of the nanobeam which functions as a lightguide
Implementation Method 3
The plurality of holes are arranged in a row along the nanobeam and are sized and spaced apart to form a zero point-defect resonator
Data Source
AI summary
An LED structure is formed in a nanobeam on a semiconductor base and includes three nanobeam sections. A central section is the LED and it is formed by a bottom germanium doped layer, a middle germanium-tin layer and a top germanium layer that is doped oppositely from the bottom germanium layer. Left and right germanium nanobeam sections extend outwardly from the left and right ends of the central section. Metal contacts are formed on the top and bottom layers and an electrical circuit is connected to the metal contacts and provides an electrical signal that energizes the middle section and causes it to emit light, some of which is transmitted by the left and right nanobeams. Cylindrical holes are formed in the nanobeam and are sized and spaced apart to form a zero point-defect resonator. The diameters of the holes are reduced as they move further away from the central section in accordance with a Gaussian taper. The LED is configured and dimensioned to have a maximum modulation rate from about 1.6 GHz to about 0.4 GHz. The bottom layer is configured such that the metal contact on the bottom layer is spaced away from the middle layer to thereby reduce metal damping of the LED.