Stressor-Defined Qubit Confinement for Stable Valley Splitting
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Solution Overview
Problem
Existing semiconductor qubit devices face challenges such as decoherence due to strain fluctuations and non-uniformity in lattice strain, leading to deteriorated quantum properties and shared gate control issues, which affect the stability and reliability of quantum states.
Innovation Solution
A semiconductor component with a stressor layer that applies spatially varying lattice strain to the confinement layer, combined with confinement gate electrodes, to create a strain-based confinement potential profile, reducing the need for electrostatic confinement and improving valley splitting and stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If electrostatic confinement is used to confine charge carriers in quantum dots, then quantum state stability is improved, but device complexity increases due to multiple gate electrodes and control voltages
Solution Approach 1:
The patent extracts the confinement function from purely electrostatic gates by introducing a stressor layer that provides strain-based confinement. The stressor layer is patterned with stressor recesses that create lateral strain fields, eliminating the need for complex multi-electrode gate structures while maintaining quantum dot stability.
Solution Approach 2:
The patent changes the confinement mechanism from electrostatic potential control to strain field control. By modifying the physical parameter of lattice strain through the stressor layer, the system achieves carrier confinement without requiring multiple voltage-controlled gates, thereby reducing device complexity.
2Ease of manufacture
If uniform lattice strain is applied to the confinement layer, then manufacturing is simplified, but quantum property deterioration occurs due to strain fluctuations and non-uniformity
Solution Approach 1:
The stressor layer is patterned with local stressor recesses that create spatially varying strain fields. Different regions of the confinement layer experience different strain magnitudes and directions, optimized for their specific function (carrier confinement, valley splitting, or quantum dot formation), thereby achieving both manufacturing simplicity and quantum property stability.
Solution Approach 2:
The patterned stressor recesses provide built-in feedback for strain distribution, creating self-correcting strain fields that automatically compensate for fluctuations. The stressor layer structure responds to local conditions by concentrating or distributing strain as needed, maintaining uniform quantum properties across the device.
3Device complexity
If strain-based confinement is used instead of electrostatic confinement, then device complexity is reduced, but manufacturing precision requirements increase for stressor layer patterning
Solution Approach 1:
The patent replaces the mechanical/electrical system of multiple gate electrodes with a strain-based system using the stressor layer. The stressor recesses are formed using standard semiconductor patterning techniques, substituting complex multi-layer gate fabrication with a more manageable single-layer strain patterning process.
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
Enhances the reliability and stability of quantum states by reducing strain fluctuations and improving valley splitting, while minimizing the number of confinement gate electrodes and control voltages, thus enhancing the performance of quantum computing devices.
Implementation Method 1
a stressor layer below, on top or embedded in the dielectric layer and arranged to apply additional, spatially varying lattice strain to the active layer stack, in particular to the confinement layer, for generating a strain-based second confinement potential component
Implementation Method 2
confinement gate electrodes for receiving a respective electrical confinement control voltage and arranged for applying the respective electrical confinement control voltage to the active layer stack for jointly generating a first electrostatic confinement potential profile component
Implementation Method 3
one or more barrier layers for establishing a quantum confinement of charge carriers to not more than two-dimensions in the confinement layer
Implementation Method 4
the stressor recess structure defines a one-dimensional strain-induced carrier confinement region in the confinement layer... improving valley splitting and stability
Data Source
Figure 1
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Figure 3~4
AI summary
A semiconductor component, in particular a qubit device, comprises an active layer stack (304) with a confinement layer, or quantum well, and one or more barrier layers for establishing a quantum confinement of charge carriers in the vertical direction, a dielectric layer (112 see figure 1), and confinement gate electrodes (120 see figure 1) for respective electrical confinement control voltage, jointly generating a first electrostatic confinement potential profile component of a total lateral confinement potential profile in the confinement layer. A stressor layer (328) below, on top or embedded in the dielectric layer (318) applies additional, spatially varying lattice strain, in particular to the confinement layer (304), for generating a strain-based second confinement potential component of the total lateral confinement potential profile. The stressor layer comprises a stressor recess (330) defining a one-dimensional strain-induced carrier confinement region in the confinement layer (304). The confinement control voltages and structured stressor layer limit localization of charge carriers to a volume spanning less than two dimensions and create an energy split between at least two confined charge carrier spin states.