Superlattice Semiconductor Structure for High Mobility
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Solution Overview
Problem
Current semiconductor technologies, despite advancements in carrier mobility and strain engineering, face limitations in enhancing the performance of optical semiconductor devices, particularly in achieving higher charge carrier mobility and reducing defects for integrated circuits with optical components.
Innovation Solution
The development of a superlattice structure with stacked groups of semiconductor monolayers and non-semiconductor layers constrained within the crystal lattice, which reduces the effective mass of charge carriers, enhances mobility, and provides piezoelectric, pyroelectric, and ferroelectric properties, while acting as a barrier to dopant diffusion and scattering, thereby improving device performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If strained material layers are used to enhance carrier mobility, then device speed and performance are improved, but device complexity and manufacturing difficulty increase
Solution Approach 1:
The patent segments the semiconductor structure into distinct functional layers including superlattice layers, buffer layers, and active device layers. Each layer serves a specific purpose: the superlattice layers provide strain engineering for mobility enhancement, while buffer layers manage dislocation. This segmentation allows complex functionality to be achieved through modular layer design rather than monolithic complex structures.
Solution Approach 2:
The patent employs composite material structures, specifically superlattice compositions alternating between different semiconductor materials (e.g., GaAs/AlAs, InGaAs/AlAs). These composite layers create localized strain fields that enhance carrier mobility without requiring the entire device structure to be complex. The composite nature allows tailored mechanical and electrical properties in different regions.
2Reliability
If superlattice structures are implemented to reduce effective mass and enhance mobility, then charge carrier mobility is improved, but manufacturing precision requirements increase
Solution Approach 1:
The patent systematically varies critical parameters including layer thickness (controlling strain magnitude), composition ratios (controlling material properties), and layer sequencing (controlling strain distribution). By optimizing these parameters, the superlattice achieves desired mobility enhancement while remaining compatible with standard semiconductor manufacturing capabilities. The buffer layer thickness and composition are specifically tuned to manage dislocation density.
Solution Approach 2:
The patent implements buffer layers and intermediate transition layers before the active device regions. These preliminary layers are designed to gradually transition between different crystal structures and compositions, reducing dislocation density before carriers enter the active region. This preliminary structuring ensures high-quality active layers without requiring extreme manufacturing precision throughout the entire growth process.
3Adaptability or versatility
If vertically integrated optical and electronic devices are created, then device functionality and performance are enhanced, but device complexity increases
Solution Approach 1:
The patent merges optical and electronic device functionalities into a single vertically integrated structure. The superlattice layers serve dual purposes: they provide strain engineering for electronic device mobility enhancement while simultaneously acting as optical waveguide layers for light confinement. This merging eliminates the need for separate optical and electronic device fabrication, reducing overall system complexity despite enhanced functionality.
Solution Approach 2:
The superlattice structure exhibits multi-functionality, serving as both an electronic active layer (providing high-mobility channels for transistors) and an optical waveguide (confining and guiding light). The same material composition and structural design that enhance electron mobility also provide the refractive index contrast needed for optical confinement. This universality allows a single structure to fulfill multiple device 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 superlattice structure achieves higher charge carrier mobility, reduces defects, and enhances the performance of semiconductor devices by lowering conductivity effective mass, improving device mobility, and providing advantageous energy band structures for opto-electronic applications.
Implementation Method 1
The superlattice may include a plurality of stacked groups of layers, with each group of layers comprising a plurality of stacked base semiconductor monolayers defining a base semiconductor portion, and at least one non-semiconductor monolayer constrained within a crystal lattice of adjacent base semiconductor portions
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
acting as a barrier to dopant diffusion and scattering, thereby improving device performance
Implementation Method 4
provides piezoelectric, pyroelectric, and ferroelectric properties
Implementation Method 5
provides piezoelectric, pyroelectric, and ferroelectric properties
Data Source
AI summary
A method for making a semiconductor device may include forming a plurality of waveguides on a substrate, and forming a superlattice overlying the substrate and waveguides. The superlattice may include a plurality of stacked groups of layers, with each group of layers comprising a plurality of stacked base semiconductor monolayers defining a base semiconductor portion, and at least one non-semiconductor monolayer constrained within a crystal lattice of adjacent base semiconductor portions. The method may further include forming an active device layer on the superlattice comprising at least one active semiconductor device.