Silicon Carbide High-Resistance Resistor With Ohmic Contact Layers
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Solution Overview
Problem
Existing high-resistance resistors face challenges in achieving high resistance values while maintaining stability in extreme environments, and they often require complex manufacturing processes or are limited by material properties such as Teflon, which can introduce false voltage and current readings due to deformation.
Innovation Solution
A high-resistance resistor based on silicon carbide is developed, utilizing a semi-insulating 4H—SiC substrate with symmetrical atomic-thickness aluminum oxide insulating layers and conductive metal electrodes made of gold, silver, copper, or aluminum, which form ohmic contacts to achieve resistance values of 100 TΩ or more.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a metal electrode is made directly on a silicon carbide substrate, then the manufacturing process is simple, but Schottky contact is obtained instead of ohmic contact, making the element nonlinear and unusable as a high-resistance resistor
Solution Approach 1:
An aluminum oxide insulating layer with thickness of 0.2 nm to 2 nm is introduced as an intermediary between the metal electrode and the semi-insulating silicon carbide substrate. This thin insulating layer enables ohmic contact by preventing Schottky barrier formation while maintaining electrical connectivity, thus resolving the contradiction between manufacturing simplicity and contact characteristic reliability.
2Ease of manufacture
If organic materials like Teflon are used for high-resistance resistors, then the manufacturing process is simple and cost-effective, but deformation introduces charges that cause false voltage and current readings
Solution Approach 1:
The invention changes the material parameter from organic materials (Teflon, polystyrene, polyethylene) to semi-insulating silicon carbide, which maintains stable electrical properties under extreme conditions including high temperature, high humidity, and radiation. This parameter change eliminates the deformation-induced charge accumulation problem while preserving manufacturing feasibility through compatible semiconductor fabrication processes.
3Measurement precision
If sapphire is used as the insulating material for high-resistance resistors, then measurement precision is improved for currents in the range of 10^-18 A to 10^-15 A, but the price increases and the manufacturing process becomes complicated
Solution Approach 1:
The invention replaces expensive sapphire with semi-insulating silicon carbide, which offers comparable or superior electrical stability for micro-current measurement. The silicon carbide substrate can be processed using standard semiconductor manufacturing techniques, significantly reducing both material cost and manufacturing complexity while achieving resistance values of 100 TΩ or more.
4Measurement precision
If the resistance of a resistor is increased to measure weaker currents, then measurement precision is improved, but the stability in extreme environments becomes more difficult to maintain
Solution Approach 1:
The invention uses a composite structure consisting of a semi-insulating silicon carbide substrate with aluminum oxide insulating layers and metal electrodes. The silicon carbide provides high resistance (100 TΩ or more) and extreme environment stability, while the aluminum oxide layers enhance electrical insulation and contact properties. This composite material approach simultaneously achieves high measurement precision for weak currents and maintains stability under extreme conditions including high temperature, high voltage, and radiation.
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 silicon carbide-based high-resistance resistor demonstrates stability in extreme environments, enabling precise current measurement and generation, and is suitable for direct monolithic integration with silicon carbide transistors, promoting the development of silicon carbide integrated circuit technology.
Implementation Method 1
conductive metal electrodes are formed at two sides of the aluminum oxide insulating layers through evaporation... making an ohmic contact electrode on a semi-insulating silicon carbide substrate
Data Source
AI summary
Disclosed is a high-resistance resistor based on silicon carbide. The resistor includes a semi-insulating 4H—SiC silicon carbide substrate, a silicon surface and a carbon surface of the silicon carbide substrate are provided with symmetrical atomic-thickness aluminum oxide insulating layers, thicknesses of the aluminum oxide insulating layers are 0.2 nm-2 nm, conductive metal electrodes are formed at two sides of the aluminum oxide insulating layers through evaporation, and thicknesses of the metal electrodes are 100 nm-500 nm. The present disclosure uses a high-resistance resistor based on silicon carbide that has the above structure, makes an ohmic contact electrode on a semi-insulating silicon carbide substrate, thus obtaining a resistor with a resistance of 100 TΩ or more, and satisfying requirements of the precision measurement industry.