Strained Germanium Photonics for On-Chip Light Emission
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current optical systems using group IV semiconductor materials for light emission face inefficiencies due to indirect bandgap properties, limiting their ability to achieve high-frequency data transmission and integration with silicon-based ULSI chips, particularly in generating light on-chip for photonic functions within modern computing systems.
Innovation Solution
The introduction of biaxial tensile strain in germanium regions within optical devices transforms them into direct bandgap semiconductors, enabling efficient light emission and detection by altering the band structure, allowing for the creation of optical layers with strained germanium regions that can emit or detect light effectively.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If group IV semiconductor materials (silicon, germanium) are used for light emission in photonics systems, then ease of manufacturing and integration with silicon-based ULSI chips is improved, but light emission efficiency deteriorates due to indirect bandgap properties
Solution Approach 1:
The patent applies parameter changes by introducing biaxial tensile strain to modify the band structure of germanium, transforming it from indirect to direct bandgap. This strain engineering approach changes the fundamental electronic parameters of the material, enabling efficient light emission while maintaining compatibility with silicon-based manufacturing processes. The strained germanium layer is grown on a silicon substrate with specific lattice mismatch control to achieve the desired strain state and direct bandgap configuration.
2Adaptability or versatility
If conventional indirect bandgap materials are used for on-chip light emission, then integration with existing CMOS process flows is improved, but light emission efficiency and suitability for high-frequency data transmission deteriorates
Solution Approach 1:
The patent transforms germanium from an indirect to direct bandgap material through controlled biaxial tensile strain, enabling it to support high-frequency data transmission. The strain engineering modifies the electronic band structure parameters, making the material suitable for high-speed optical interconnects while maintaining compatibility with standard CMOS fabrication processes.
Solution Approach 2:
The patent employs a composite structure consisting of strained germanium layers grown on silicon substrates, combining the advantages of both materials. The germanium provides direct bandgap properties for efficient light emission, while the silicon substrate ensures compatibility with existing CMOS infrastructure. This composite approach enables seamless integration of photonic functions with electronic circuitry.
3Adaptability or versatility
If light emission is implemented using externally supplied light and Raman effect conversion, then wavelength conversion is achieved, but light emission efficiency deteriorates due to low conversion efficiency
Solution Approach 1:
The patent fundamentally changes the emission mechanism by creating direct bandgap conditions in germanium through strain engineering. Instead of relying on inefficient Raman scattering processes, the strained germanium directly emits light through radiative recombination, achieving high efficiency wavelength generation without the need for external light sources or conversion processes.
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 approach enhances the efficiency of light emission and detection processes, enabling the development of high-speed optical interconnects and reducing manufacturing costs by integrating photonic functions directly on silicon chips, addressing the limitations of existing group IV semiconductor materials.
Implementation Method 1
The introduction of biaxial tensile strain in germanium regions within optical devices transforms them into direct bandgap semiconductors
Implementation Method 2
enabling efficient light emission and detection by altering the band structure
Implementation Method 3
enabling efficient light emission and detection
Data Source
AI summary
Tensile strained germanium is provided that can be sufficiently strained to provide a nearly direct band gap material or a direct band gap material. Compressively stressed or tensile stressed stressor materials in contact with germanium regions induce uniaxial or biaxial tensile strain in the germanium regions. Stressor materials may include silicon nitride or silicon germanium. The resulting strained germanium structure can be used to emit or detect photons including, for example, generating photons within a resonant cavity to provide a laser.