Carbon-Doped GaN Photoconductive Switches With Optical Quenching
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Solution Overview
Problem
Traditional photoconductive semiconductor switches (PCSS) are unable to meet the requirements for exceptionally fast turn-off times and support larger ranges of pulsed power and radio frequencies in high-power applications, and existing semiconductor materials like silicon (Si) and gallium arsenide (GaAs) suffer from material defects and short carrier lifetimes, limiting their effectiveness.
Innovation Solution
A carbon-doped gallium nitride (GaN:C) PCSS is operated using specific wavelength ranges of laser light to achieve fast switching, with ultraviolet (UV) light triggering conductivity and infrared (IR) light quenching it, enabling sub-nanosecond turn-off times and high voltage blocking, supported by integrated UV and IR emitters and optical bipolar junction transistors (BJTs).
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If traditional photoconductive semiconductor switch architectures are used, then device simplicity is maintained, but turn-off time is too slow and pulsed power range is limited
Solution Approach 1:
The patent segments the control function into two distinct optical pathways: one for turn-on (UV illumination generating electron-hole pairs) and one for turn-off (infrared illumination releasing holes from carbon traps). This segmentation enables independent optimization of switching speeds without compromising architectural simplicity.
Solution Approach 2:
The patent changes the material parameter by introducing carbon doping into gallium nitride, creating deep trap levels that enable optical control of conductivity. This parameter change allows sub-nanosecond turn-off times while maintaining a relatively simple photoconductive switch architecture.
2Reliability
If traditional semiconductor materials like silicon or gallium arsenide are used, then manufacturing familiarity is maintained, but carrier lifetime is too short and material defects limit performance
Solution Approach 1:
The patent uses carbon-doped gallium nitride, combining the advantages of wide-bandgap GaN material with carbon dopant atoms that create deep trap levels. This composite material structure provides long carrier lifetimes and high breakdown voltages while being compatible with existing semiconductor fabrication processes.
3Power
If carbon-doped gallium nitride material is used, then switching speed and voltage blocking are improved, but device structure complexity increases due to integrated emitters
Solution Approach 1:
The patent merges the UV and infrared emitters into an integrated structure that can be monolithically fabricated with the GaN:C layer. This combining approach enables high voltage blocking capability while managing structural complexity through integrated design rather than separate discrete components.
4Adaptability or versatility
If sub-nanosecond switching is achieved, then pulsed power application range is expanded, but energy loss during switching increases
Solution Approach 1:
The patent replaces traditional electrical switching mechanisms with optical control mechanisms. By using light to control conductivity through carrier generation and trap release, the system achieves sub-nanosecond switching speeds with reduced electromagnetic interference and lower switching losses compared to conventional electrical switching.
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 GaN:C PCSS provides exceptionally fast switching speeds, high voltage blocking, and low conduction/switching loss, suitable for power electronics applications with improved control and power density integration, overcoming limitations of traditional PCSS architectures.
Implementation Method 1
illuminating a carbon-doped gallium nitride material of the photoconductive semiconductor switch with a first laser light within a first range of wavelengths to trigger the photoconductive semiconductor switch to a conductive state
Implementation Method 2
illuminating the carbon-doped gallium nitride material with a second laser light within a second range of wavelengths to trigger the photoconductive semiconductor switch to an insulating state
Data Source
AI summary
Devices, systems and methods for operating and using an optically quenchable carbon-doped gallium nitride photoconductive semiconductor switch (PCSS) are described. An example method includes illuminating a carbon-doped gallium nitride material of the photoconductive semiconductor switch with a first laser light within a first range of wavelengths to trigger the photoconductive semiconductor switch to a conductive state, turning off or blocking the first laser light, and illuminating the carbon-doped gallium nitride material with a second laser light within a second range of wavelengths to trigger the photoconductive semiconductor switch to an insulating state. In this example, the first range of wavelengths comprises an ultraviolet (UV) or a blue wavelength range, the second range of wavelengths comprises an infrared (IR) or a red wavelength range, and switching from the conductive state to the insulating state occurs within a sub-nanosecond range.