Side-Gated Semiconductor-Superconductor Layout for Efficient Gating
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Solution Overview
Problem
Existing semiconductor-superconductor hybrid devices face challenges such as susceptibility to damage from elevated temperatures, degradation of the semiconductor-superconductor interface due to mechanical stress and thermal budget limitations, and inefficiencies in electrostatic gating, particularly in top-gated and side-gated configurations.
Innovation Solution
The proposed solution involves a side-gated semiconductor-superconductor hybrid device where the gate electrode is integrated with the semiconductor component during selective area growth, utilizing a dielectric mask to define the position, and embedding the gate electrode within the substrate to serve as a gate dielectric, thereby improving positioning accuracy and reducing mechanical stress and thermal degradation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a separate dielectric layer is used for gating, then electrical insulation is provided, but device complexity and mechanical strain increase
Solution Approach 1:
The gate electrode and dielectric layer are merged into a single integrated gate structure formed by selective area growth. This combines the electrical insulation function and the gating function into one component, eliminating the need for separate dielectric layers and reducing overall device complexity while maintaining reliable electrical insulation.
Solution Approach 2:
The gate structure serves multiple functions simultaneously: it provides electrical insulation, applies electrostatic gating, and acts as a structural support element. This multi-functionality reduces the number of separate components needed and simplifies the overall device architecture.
2Ease of operation
If top-gated configuration is used, then gating is achieved, but alignment precision and mechanical strain are problematic
Solution Approach 1:
Instead of placing the gate electrode on top of the semiconductor-superconductor interface (top-gated), the gate is positioned at the side of the semiconductor component. This inverted configuration eliminates alignment difficulties between the gate and the interface, as the gate is formed independently by selective area growth without requiring precise alignment with the superconductor-semiconductor interface.
Solution Approach 2:
The device is segmented into distinct functional regions: the gate electrode is formed in a separate lateral position from the semiconductor-superconductor interface. This segmentation allows independent optimization of each component's fabrication without compromising alignment precision.
3Ease of operation
If side-gated configuration with gap is used, then gating is achieved, but dielectric constant is low and alignment is difficult
Solution Approach 1:
The gate structure uses composite material formation through selective area growth, where the gate electrode material is grown directly adjacent to the semiconductor component. This eliminates the need for low dielectric constant gaps and vacuum spaces, replacing them with a solid-state composite structure that provides high dielectric constant and efficient gating.
Solution Approach 2:
The gate structure acts as an intermediary between the control electrode and the semiconductor component, providing efficient electrostatic coupling without requiring large gaps. The selective area growth creates an optimal intermediate structure that maximizes gating efficiency while maintaining proper electrical isolation.
4Adaptability or versatility
If multiple separate components are used, then functional requirements are met, but thermal stability decreases
Solution Approach 1:
Multiple functional components (gate electrode, dielectric layer, and structural support) are merged into a single integrated gate structure formed by selective area growth. This reduces the number of interfaces and material boundaries that could be thermally unstable, while maintaining all necessary functional capabilities through the multi-functional design of the integrated structure.
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 enhances electrostatic gating efficiency, reduces mechanical stress on the semiconductor-superconductor interface, and maintains the device's integrity by minimizing thermal exposure, thus enabling more effective operation and fabrication of quantum computing qubits.
Implementation Method 1
The superconductor causes a proximity effect in the adjacent semiconductor, whereby a region of the semiconductor near the interface with the superconductor also exhibits superconducting properties.
Implementation Method 2
Another condition for inducing the topological phase where MZMs can form is the application of a magnetic field in order to lift the spin degeneracy in the semiconductor. Spin degeneracy can be lifted by means of a magnetic field, causing an energy level spilt between the differently spin-polarized electrons. This is known as the Zeeman effect.
Implementation Method 3
Inducing MZMs typically also requires gating the nanowire with an electrostatic potential. The electrostatic potential is applied using a gate electrode. Applying an electrostatic potential manipulates the number of charge carriers in the conductance band or valence band of the semiconductor component.
Data Source
AI summary
One aspect provides semiconductor-superconductor hybrid device comprises a substrate, a first semiconductor component arranged on the substrate, a superconductor component arranged to be capable of energy level hybridisation with the first semiconductor component, and a second semiconductor component arranged as a gate electrode for gating the first semiconductor component. Another aspect provides a semiconductor-superconductor hybrid device, comprising: a substrate; a semiconductor component arranged on the substrate; a gate electrode for gating the semiconductor component; and a superconductor component capable of undergoing energy level hybridisation with the semiconductor component; wherein the gate electrode is arranged in a channel in the substrate. Also provided are methods of fabricating the semiconductor-superconductor hybrid devices.