Superlattice Opto-Electronic Device for Charge Carrier Mobility
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Solution Overview
Problem
Current semiconductor devices face limitations in charge carrier mobility, which hinders device speed and power efficiency, particularly in optical devices like solar cells, where large surface areas are required for inefficient amorphous silicon detectors.
Innovation Solution
A multiple-wavelength opto-electronic device utilizing a superlattice structure with stacked semiconductor and non-semiconductor monolayers, where the non-semiconductor monolayer is constrained within the crystal lattice of adjacent semiconductor portions, enhancing charge carrier mobility and providing a direct bandgap for improved efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If amorphous silicon is used in optical detectors, then the device can be manufactured with simpler processes, but the charge carrier mobility is low requiring large surface areas
Solution Approach 1:
The patent employs a composite material structure consisting of silicon layers interspersed with non-semiconductor monolayers (such as oxygen, nitrogen, or carbon layers). This composite approach combines the manufacturing advantages of silicon with the mobility-enhancing properties of the intercalated layers, achieving high charge carrier mobility while maintaining ease of manufacture through established semiconductor fabrication processes.
Solution Approach 2:
The invention introduces non-semiconductor monolayers at specific locations within the silicon crystal lattice to create localized regions of enhanced charge carrier mobility. These monolayers are positioned at interfaces or within specific layers to optimize electrical properties without compromising the overall structural integrity or manufacturing simplicity of the device.
2Device complexity
If conventional semiconductor structures are used, then the device design is simpler, but the charge carrier mobility is insufficient for high-speed operation
Solution Approach 1:
The patent modifies the physical and chemical parameters of the semiconductor structure by incorporating non-semiconductor monolayers with specific atomic compositions and arrangements. These parameter changes—such as introducing oxygen, nitrogen, or carbon layers with controlled thicknesses and positions—directly enhance charge carrier mobility and enable high-speed operation while maintaining a relatively simple overall device architecture.
Solution Approach 2:
The invention embeds non-semiconductor monolayers within the silicon crystal lattice structure, creating a nested configuration where atomic layers of different materials are integrated at the nanoscale. This nested structure allows the device to achieve enhanced mobility characteristics without significantly increasing macroscopic structural complexity.
3Productivity
If larger surface areas are used in solar cells, then more light can be captured, but the device weight and material consumption increase
Solution Approach 1:
The patent utilizes composite material structures with silicon and non-semiconductor monolayers to achieve superior charge carrier mobility, which enhances the efficiency of light-to-electricity conversion. This improved efficiency allows solar cells to capture sufficient light with smaller active areas, thereby reducing overall device weight and material consumption while maintaining or improving productivity.
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 superlattice structure achieves higher charge carrier mobility and efficiency in opto-electronic devices, enabling more effective solar cell performance with reduced surface area and weight requirements, and can be used in both detectors and transmitters.
Implementation Method 1
Electrons having a smaller effective mass, and which have been induced by an electric field applied to the gate electrode, are confined in the second silicon layer
Implementation Method 2
The resulting biaxial strain in the upper silicon layer alters the carrier mobilities enabling higher speed and/or lower power devices
Implementation Method 3
U.S. Pat. No. 5,357,119 to Wang et al. discloses a Si—Ge short period superlattice with higher mobility achieved by reducing alloy scattering in the superlattice
Data Source
AI summary
A multiple-wavelength opto-electronic device may include a substrate and a plurality of active optical devices carried by the substrate and operating at different respective wavelengths. Each optical device may include a superlattice comprising a plurality of stacked groups of layers, and each group of layers may include a plurality of stacked semiconductor monolayers defining a base semiconductor portion and at least one non-semiconductor monolayer thereon.