Lateral Heterostructure Quantum Dots With Gate-Aligned Spin Qubit Confinement
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Solution Overview
Problem
The scalability of quantum computing devices is hindered by the need for multiple additional gates to set confinement potential and achieve discrete energy levels in physical spin qubits, which complicates the alignment of control gates and limits the fabrication yield and density of quantum dots.
Innovation Solution
A method for forming semiconductor structures with isolated coupled quantum dots using template-assisted selective epitaxy (TASE) to achieve geometrically defined fin-like segments, allowing for precise alignment of gate structures and eliminating the need for additional confinement gates, enabling dense packing and scalable integration of quantum dots.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If multiple additional gates are used to set confinement potential and achieve discrete energy levels, then the quantum dot confinement and energy level control are improved, but the device complexity and fabrication difficulty increase
Solution Approach 1:
The invention extracts the confinement function from separate control gates and integrates it into the quantum dot structure itself through geometric design. The fin-like segments with specific aspect ratios provide inherent confinement, eliminating the need for additional dedicated confinement gates and simplifying the overall device architecture.
Solution Approach 2:
The invention performs preliminary structuring of the semiconductor layer to create fin-like segments with predetermined geometric characteristics before applying control gates. This pre-formed geometry establishes the confinement potential and discrete energy levels in advance, reducing the complexity of subsequent gate operations.
2Manufacturing precision
If traditional fabrication techniques are used without geometric definition, then the manufacturing process is simpler, but the alignment precision and density of quantum dots are reduced
Solution Approach 1:
The invention segments the semiconductor layer into fin-like structures with specific geometric characteristics. This segmentation provides natural alignment references and defines precise positions for quantum dots, enabling high alignment precision while maintaining compatibility with standard fabrication techniques.
Solution Approach 2:
The invention changes the geometric parameters of the semiconductor structure, specifically creating fin-like segments with controlled aspect ratios and dimensions. These parameter changes enable precise quantum dot formation and alignment without requiring complex additional fabrication steps.
3Quantity of substance
If the linear structure width is reduced to increase quantum dot density, then the packing density is improved, but the manufacturing precision and control over quantum dot formation are reduced
Solution Approach 1:
The invention uses asymmetric fin-like segments with specific width-to-length ratios to maintain manufacturing precision even as density increases. The asymmetric geometry provides distinct confinement characteristics that enable precise quantum dot formation in densely packed configurations.
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 allows for precise control of quantum dot alignment and scalability to thousands of devices, overcoming the challenge of gate alignment and enabling efficient integration of control lines and read-out circuits within traditional semiconductor fabrication techniques.
Implementation Method 1
epitaxial and laterally filling the hollow template with a first semiconductor material different to the silicon such that the hollow template is filled up to a first length extending from the source area, continuing the epitaxial and laterally filling the hollow template with an alternating sequence of lateral thin layers of a second semiconductor material and a third semiconductor material
Data Source
AI summary
A method for forming a semiconductor structure comprising isolated coupled quantum dots defining a physical spin qubit is disclosed. The method comprises structuring the doped silicon layer using an SIO substrate with a source area structure, a linear structure extending from the source area, gate structures extending vertically to a main extension direction of the linear structure, covering the structures with an oxide, removing the oxide at a lateral end of the linear structure, laterally etching back the linear structure between the blanket oxide and the SOI isolator, epitaxial filling the hollow template with a first semiconductor material different from the silicon, continuing the epitaxial and laterally filling the hollow template with an alternating sequence of lateral thin layers of a second and a third semiconductor material, and continuing the epitaxial filling the hollow template with the first semiconductor material until an end of the hollow template is reached.