Semiconductor Superlattices With Thermal-Stability-Driven Atom Migration
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Solution Overview
Problem
Current semiconductor devices do not fully leverage advanced semiconductor materials and processing techniques to achieve optimal performance in terms of charge carrier mobility and thermal stability.
Innovation Solution
The method involves forming superlattices with stacked groups of semiconductor and non-semiconductor monolayers, where the second superlattice has greater thermal stability than the first, allowing non-semiconductor atoms to migrate and enhance thermal stability further, and a semiconductor layer is formed above these superlattices at high temperatures to achieve improved charge carrier mobility.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If superlattices with non-semiconductor monolayers are formed to enhance charge carrier mobility, then mobility is improved, but thermal stability deteriorates
Solution Approach 1:
The superlattice is divided into multiple groups of layers, with each group containing semiconductor monolayers and non-semiconductor monolayers. This segmentation allows different regions to serve different functions: semiconductor layers provide structural integrity and thermal stability, while non-semiconductor layers enhance charge carrier mobility through strain effects and band structure modification.
Solution Approach 2:
Different groups of layers are assigned different thermal stabilities, creating local variations in material properties. The second superlattice has greater thermal stability than the first, allowing non-semiconductor atoms to migrate preferentially toward the second superlattice during heating, thereby concentrating the mobility-enhancing elements in regions where they are most effective while maintaining overall structural stability.
2Quantity of substance
If non-semiconductor monolayers are incorporated into superlattices to reduce effective mass, then effective mass is reduced, but thermal stability during high-temperature processing deteriorates
Solution Approach 1:
The superlattices are constructed with predetermined thermal stability characteristics before high-temperature processing. The second superlattice is designed with greater thermal stability from the outset, creating a gradient that guides non-semiconductor atom migration during subsequent heating. This preliminary arrangement ensures that when high-temperature processing occurs, the non-semiconductor atoms migrate to designated regions rather than causing random degradation.
Solution Approach 2:
The semiconductor monolayers act as intermediary structures between the non-semiconductor monolayers and the bulk semiconductor material. These intermediary layers facilitate controlled interaction during thermal processing, allowing non-semiconductor atoms to migrate through or between semiconductor layers without causing catastrophic failure, thereby mediating between the conflicting requirements of low effective mass and high thermal stability.
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 results in semiconductor devices with reduced effective mass for charge carriers, increased mobility, and enhanced thermal stability, suitable for various device applications including opto-electronic devices.
Implementation Method 1
heating the first and second superlattices to cause non-semiconductor atoms from the first superlattice to migrate toward the at least one non-semiconductor monolayer of the second superlattice
Implementation Method 2
The resulting biaxial strain in the upper silicon layer alters the carrier mobilities enabling higher speed and/or lower power devices
Data Source
AI summary
A method for making a semiconductor device may include forming first and second superlattices adjacent a semiconductor layer. Each of the first and second superlattices may include stacked groups of layers, with each group of layers including 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 second superlattice may have a greater thermal stability with respect to non-semiconductor atoms therein than the first superlattice. The method may further include heating the first and second superlattices to cause non-semiconductor atoms from the first superlattice to migrate toward the at least one non-semiconductor monolayer of the second superlattice.