Epitaxial Oxide Transistor Structure for High-Breakdown RF Switching
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Solution Overview
Problem
Existing semiconductor devices, such as UV LEDs and RF switches, face challenges in handling high voltages and achieving efficient optical wavelength conversion due to the limitations of low bandgap semiconductors, which require multiple devices in series and lack compatibility with microwave circuits.
Innovation Solution
Employing epitaxial oxide materials with varying compositions, crystal symmetries, and bandgaps, forming structures like superlattices and heterostructures, which provide a template for growth and enable high breakdown voltages and efficient carrier multiplication.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If low bandgap semiconductors are used in RF switches, then device complexity is reduced, but breakdown voltage is insufficient requiring multiple devices in series
Solution Approach 1:
The patent changes the fundamental material parameter (bandgap) from low bandgap semiconductors to wide bandgap semiconductors, enabling single-device operation at high voltages. This parameter change resolves the contradiction by allowing one transistor to handle voltages that previously required series connections of multiple transistors.
Solution Approach 2:
The patent employs composite material structures including heterostructures and superlattices combining different wide bandgap semiconductor materials. These composite structures enable simultaneous achievement of high breakdown voltage and controlled electrical properties, resolving the contradiction between reduced device complexity and maintained reliability.
2Reliability
If wide bandgap semiconductors are used in RF switches, then breakdown voltage is improved, but impedance matching with microwave circuits becomes difficult
Solution Approach 1:
The patent applies local quality by creating regions with different material compositions and electrical properties within the device structure. Heterostructure interfaces and doped regions provide localized impedance transformation, enabling wide bandgap devices to match microwave circuit impedances while maintaining high breakdown voltage characteristics.
Solution Approach 2:
The patent introduces intermediate layers and transition regions that act as mediators between the wide bandgap semiconductor and microwave circuits. These intermediary structures provide impedance transformation and coupling, resolving the contradiction between high voltage capability and ease of impedance matching.
3Reliability
If epitaxial oxide materials are used, then breakdown voltage and optical wavelength conversion are improved, but device manufacturing complexity increases
Solution Approach 1:
The patent employs preliminary action by using epitaxial growth to pre-form highly ordered crystal structures with controlled compositions and properties before device fabrication. This preliminary structuring of oxide materials enables subsequent processing steps to be more straightforward, offsetting the increased manufacturing complexity with improved material quality and device performance.
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 use of epitaxial oxide materials enhances semiconductor devices with high breakdown voltages and efficient optical wavelength conversion, simplifying RF switch impedance matching and improving device performance.
Implementation Method 1
The semiconductor device has a high breakdown voltage due to the properties of the epitaxial oxide materials therein. In some embodiments, the semiconductor device uses impact ionization mechanisms for carrier multiplication.
Data Source
AI summary
The techniques described herein relate to a transistor including a substrate including sapphire, an epitaxial channel layer on the substrate, and an epitaxial gate layer on the channel layer. The epitaxial channel layer can include α-Ga2O3, with a first bandgap. The epitaxial gate layer can include an oxide material with a second bandgap, wherein the second bandgap is wider than the first bandgap. The transistor can also include electrical contacts, including: a source electrical contact coupled to the epitaxial channel layer; a drain electrical contact coupled to the epitaxial channel layer; and a gate electrical contact coupled to the epitaxial gate layer.