Electro-Optical High-Voltage Pulse Generator for Atom Probe Mass Resolution
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Solution Overview
Problem
Current high-voltage pulse generators for tomographic atom probes fail to produce pulses with steep edges and short duration, leading to degraded mass resolution due to the production of pulses with parabolic shapes rather than square-wave pulses, which results in a broad energy spectrum and reduced spectral resolution.
Innovation Solution
A semiconductor chip-based system that uses light pulses to control the electrical connection, allowing for the generation of high-voltage pulses with extremely short rise and fall times, typically a few picoseconds, and maintaining a constant amplitude, optimizing the mass resolution by producing pulses with steep edges and a short duration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional high-voltage pulse generators are used, then the device complexity is reduced, but the pulse edge steepness and duration are degraded, leading to poor mass resolution
Solution Approach 1:
The patent introduces a semiconductor switch as an intermediary component between the voltage source and the sample. This switch, controlled by light pulses, enables precise temporal control of the high-voltage pulse application, achieving steep edges and short duration pulses that improve mass resolution while maintaining manageable device complexity.
Solution Approach 2:
The patent replaces conventional electrical switching mechanisms with an optically-controlled semiconductor switch. This substitution allows for much faster switching speeds (picosecond scale) compared to mechanical or conventional electrical switches, thereby achieving the required pulse edge steepness and duration for high mass resolution.
2Measurement precision
If pulses with parabolic shape are produced, then the device operation is simplified, but the energy spectrum broadens, reducing spectral resolution
Solution Approach 1:
The patent employs periodic light pulse trains to control the semiconductor switch, creating a periodic high-voltage pulse train with precise timing. This periodic control mechanism enables the generation of square-wave pulses with steep edges, preventing energy spectrum broadening while maintaining ease of operation through systematic pulse sequencing.
Solution Approach 2:
The patent changes the temporal parameters of the voltage pulse by using ultrafast optically-controlled switching. This transforms the pulse shape from parabolic (gradual rise/fall) to square-wave (steep edges), thereby narrowing the energy spectrum and improving spectral resolution without significantly complicating the operation.
3Productivity
If the pulse duration is extended to ensure complete evaporation, then the evaporation efficiency is improved, but the pulse edge steepness is reduced, degrading mass resolution
Solution Approach 1:
The patent applies preliminary high-voltage pulses in a controlled sequence, where each pulse evaporates a controlled number of atoms. The optically-controlled switching enables precise timing and duration control of each pulse, ensuring complete evaporation of the intended atomic layer while maintaining steep edges for high mass resolution.
Solution Approach 2:
The patent implements dynamic pulse control where the duration and timing of each high-voltage pulse are precisely adjusted based on the evaporation progress. This dynamic adjustment, enabled by fast optically-controlled switching, allows the system to maintain both high evaporation efficiency and steep pulse edges for superior mass resolution.
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 system achieves improved mass resolution by generating pulses with steep edges and short duration, enhancing the capability to distinguish between mass peaks and reducing detection noise, thereby improving the accuracy of material composition analysis.
Implementation Method 1
a first source emitting light pulses of wavelength λ1 to the semiconductor chip, said chip becoming conductive and closing the electrical connection when it is illuminated with a light pulse of wavelength λ1
Data Source
AI summary
A tomographic atom probe uses electrical pulses applied to an electrode in order to carry out evaporation of the sample being analyzed. In order to produce these electrical pulses, the tomographic atom probe comprises a high-voltage generator connected to an electrode by an electrical connection comprising a chip of semiconductor material. The probe also comprises a light source which can be controlled in order to generate light pulses which are applied to the semiconductor chip. Throughout the illumination, the chip is rendered conductive, which puts the high-voltage generator and the electrode in electrical contact so that a potential step is applied to the latter. The probe also comprises means for applying a voltage step of opposite amplitude to the previous step at the end of a time interval Δt0, so that the electrode finally receives a voltage pulse of duration Δt0.