Superlattice Opto-Electronic Device Charge Carrier Mobility
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Solution Overview
Problem
Despite advancements in materials engineering, semiconductor devices still require improved charge carrier mobility to enhance device speed and reduce power consumption, particularly in optical devices like solar cells, which are inefficient and require large surface areas.
Innovation Solution
A multiple-wavelength opto-electronic device is developed using 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 efficient optical detection and transmission.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If conventional semiconductor materials are used, then manufacturing is simple, but charge carrier mobility is insufficient
Solution Approach 1:
The semiconductor layer is segmented into multiple monolayer-thick alternating layers of different semiconductor materials (e.g., SiGe and Si), forming a superlattice structure. This segmentation creates distinct regions with different band structures that collectively enhance charge carrier mobility through reduced effective mass, while maintaining manufacturability via sequential epitaxial growth processes
Solution Approach 2:
The patent employs composite semiconductor materials in the superlattice structure, combining different semiconductor compounds (such as SiGe and Si) in alternating monolayers. This composite approach leverages the complementary properties of each material to achieve enhanced charge carrier mobility that cannot be obtained with single-material systems, while the thin-film nature keeps processing compatible with existing manufacturing
2Productivity
If thicker semiconductor layers are used, then manufacturing is easier, but optical efficiency decreases
Solution Approach 1:
The active layer is divided into multiple thin monolayer segments arranged in a superlattice pattern, where each monolayer contributes to the overall optical absorption and charge generation. This segmentation enables precise control of the total active thickness while maintaining high optical efficiency through the cumulative effect of multiple interfaces and the direct bandgap properties of the constituent materials
Solution Approach 2:
The patent utilizes parameter changes at the atomic scale by controlling the thickness of each monolayer and the composition ratio of alternating layers. By adjusting these parameters, the effective optical path length and band structure are optimized to achieve high detection efficiency without requiring thick layers that would be difficult to manufacture with precision
3Productivity
If solar cell surface area is reduced, then device weight decreases, but power output decreases
Solution Approach 1:
The superlattice structure employs composite semiconductor materials with direct bandgap properties that exhibit significantly higher optical absorption coefficients than conventional indirect bandgap materials. This enables the solar cell to achieve high power output from reduced surface areas, as the enhanced material properties compensate for the reduced geometric size, simultaneously decreasing device weight 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, reducing the effective mass of carriers and improving device efficiency, enabling more efficient solar cells with reduced surface area and weight requirements, while also providing piezoelectric, pyroelectric, and ferroelectric properties.
Implementation Method 1
a superlattice comprising a plurality of stacked groups of layers, and each group of layers includes a plurality of stacked semiconductor monolayers defining a base semiconductor portion and at least one non-semiconductor monolayer thereon
Implementation Method 2
at least some semiconductor atoms from opposing base semiconductor portions are chemically bound together through the at least one non-semiconductor monolayer therebetween
Implementation Method 3
providing piezoelectric, pyroelectric, and ferroelectric properties
Implementation Method 4
providing piezoelectric, pyroelectric, and ferroelectric properties
Implementation Method 5
providing piezoelectric, pyroelectric, and ferroelectric properties
Data Source
AI summary
A method for making a multiple-wavelength opto-electronic device which may include providing a substrates and forming a plurality of active optical devices to be carried by the substrate and operating at different respective wavelengths. Moreover, 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.