Optical Device Fabrication in Wide-Bandgap Semiconductors
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Solution Overview
Problem
Conventional semiconductors, such as silicon, are limited by narrow band gaps and poor thermal stability, restricting their operation to temperatures below 250°C, whereas wide-bandgap semiconductors like silicon carbide (SiC) offer superior thermal stability and properties but face challenges in doping due to hardness and low impurity diffusion coefficients, leading to defects and surface damage during high-temperature annealing.
Innovation Solution
A method involving a thermal energy beam is directed onto a wide-bandgap semiconductor substrate to change optical and electrical properties, enabling the fabrication of optical and electro-optical devices within the substrate, including the formation of electrodes and sensors for temperature, pressure, and chemical composition measurement, using laser metallization and doping techniques to enhance dopant diffusion and reduce defect generation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If ion implantation is used for doping silicon carbide, then dopant introduction is achieved, but implantation-induced defect centers are generated requiring high annealing temperatures that cause surface damage
Solution Approach 1:
The patent applies preliminary action by performing low-temperature annealing (900-1100°C) immediately after ion implantation to repair implantation-induced defects before high-temperature processing. This preliminary defect repair prevents the need for severe high-temperature annealing that would cause surface damage, while still achieving adequate dopant activation.
Solution Approach 2:
The patent changes the annealing temperature parameter from conventional high temperatures (1700°C) to optimized lower temperatures (900-1100°C). This parameter change achieves sufficient dopant activation and defect repair without causing silicon sublimation and surface redistribution damage, resolving the contradiction between dopant activation and surface integrity.
2Reliability
If high annealing temperatures are used to remove implantation defects, then defect removal is achieved, but severe surface damage occurs due to silicon sublimation and redistribution
Solution Approach 1:
The patent performs preliminary low-temperature annealing (900-1100°C) to repair implantation-induced defects before subsequent high-temperature device fabrication steps. This preliminary action reduces defect density without requiring severe high-temperature annealing that would damage the surface, thereby maintaining both reliability and manufacturing precision.
Solution Approach 2:
The patent optimizes the annealing temperature parameter to the range of 900-1100°C, which is sufficient for defect repair and dopant activation but below the threshold for severe silicon sublimation and surface redistribution. This parameter change simultaneously improves reliability by reducing defects and maintains manufacturing precision by preserving surface quality.
3Ease of manufacture
If conventional semiconductors are used, then ease of manufacture is maintained, but operating temperature is limited to below 250°C due to narrow band gap
Solution Approach 1:
The patent changes the fundamental material parameter from conventional semiconductors with narrow bandgaps to wide-bandgap semiconductors (silicon carbide, gallium nitride). This material parameter change enables operation at elevated temperatures while maintaining fabrication simplicity through optimized low-temperature annealing processes (900-1100°C) that are comparable to or simpler than conventional high-temperature processes.
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 the creation of stable optical and electro-optical devices within wide-bandgap semiconductors, enabling operation at elevated temperatures with improved dopant distribution and reduced surface damage, enhancing thermal and chemical stability, and enabling remote sensing of temperature, pressure, and chemical composition.
Implementation Method 1
directing a thermal energy beam onto a selected portion of the wide-bandgap semiconductor substrate for changing an optical property of the selected portion
Implementation Method 2
excellent thermal conductivity (490 W/m·K)
Data Source
AI summary
An optical device and method is disclosed for forming the optical device within the wide-bandgap semiconductor substrate. The optical device is formed by directing a thermal energy beam onto a selected portion of the wide-bandgap semiconductor substrate for changing an optical property of the selected portion to form the optical device in the wide-bandgap semiconductor substrate. The thermal energy beam defines the optical and physical properties of the optical device. The optical device may take the form of an electro-optical device with the addition of electrodes located on the wide-bandgap semiconductor substrate in proximity to the optical device for changing the optical property of the optical device upon a change of a voltage applied to the optional electrodes. The invention is also incorporated into a method of using the optical device for remotely sensing temperature, pressure and/or chemical composition.