The TD-800-X-HR microprobe enables the sampling of in-plane THz field components with the highest resolution. Together with a flat spectral response and high detection bandwidth, it is also suitable for near-field spectroscopic applications.
Protemics microprobe series TeraSpike is the new generation of high-performance microprobes for the photo-conductive detection of electric fields in the THz frequency range. Surface-near electric THz fields can now be measured with unprecedented resolution, signal quality and low invasiveness. The microprobes seamlessly fit into systems with optical excitation wavelengths below 860 nm and are the most cost-efficient solution to turn an existing time-domain pump/probe-system into a powerful THz near-field system for high-resolution imaging.
Smallest active THz probe-tip on the market.
Spatial resolution up to 3 um.
Frequency range 0-4 THz.
Adaptable to all laser-based THz-Systems with λ < 860 nm.
Mounting compatible with standard opto-mechanical components.
Typical optical excitation power 1-5 mW (1-5 uJ/cm2).
No bias voltage required during measurement.
Integrated overvoltage protection circuit.
Max. Spatial Resolution:
PC Gap Size:
Dark Current @ 1 V Bias:
< 0.5 nA
Photocurrent (4mW, 1 V bias, 20um focus):
> 1 uA
Detected Z-Field Component:
700 .. 860nm
Avg. Excitation Power:
0.1 .. 4 mW
Breaking the resolution limits of standard THz imaging systems:
The capability of an existing THz setup can be vastly enhanced with the implementation of a TeraSpike near-field detector with micron resolution. This covers applications ranging from contactless sheet resistance measurement, time-domain reflecto-metry for fault isolation in chip-packages to THz near-field imaging of THz devices like meta-materials or waveguides. Thanks to the low optical power requirements of the TeraSpike microprobes (typ. < 4 mW average power at 700-860nm) they are compatible to most pulsed laser sources (pulse durations < 150 fs recommended). *The T-Era-100A-800-air and T-Era-400A-800-air Sensors can be used as the THz emitter.
Q: I already own a free-space THz TDS system. Is it possible to integrate the TeraSpike microprobe and perform near-field measurements?
A: The integration of TeraSpike microprobes into an existing TDS system is usually quite simple. Especially if the system is including a photoconductive detector: In this case most required components should be already available.
Q: What is the dynamic range of your TeraSpike?
A: The effective dynamic range depends on your measurement scheme (e.g. ECOPS or Lock-in), the used emitter, integration time and other factors of the setup. With the TeraSpike TD-800-X-HRS we are usually working with a signal-to-noise-ration of 30dB in field-amplitude at short lock-in integration times well below 100ms.
Q: Is the TeraSpike an AFM-based probe?
A: No, TeraSpike microprobes fill the gap between diffraction limited mm-scale resolution and AFM-based nm-scale resolution systems. Micron-scale resolution is achieved by using large-scale translation stages and (optionally) using optical surface distance monitoring. This helps to keep the system costs comparatively low and enables measurements over large-scale areas.
Q: Which kind of laser do I need to use TeraSpike microprobes?
A: Basically, most femtosecond pulse oscillator systems with < 860 nm are compatible with our microprobes. The TeraSpike microprobe is optimized for femtosecond pulse excitation with a central wavelength around 800nm and a few mW of average optical power at repetition rates around of 80MHz.
Q: Which orientations of THz excitation beam, sample surface and TeraSpike microprobe do you recommend?
A: For highest resolution we recommend to align the microprobe cantilever and THz excitation beam in vertical direction to the samples surface. Optical excitation of the TeraSpike is recommended from the non-metalized side of the cantilever as specified in the application notes in our download section.
Q: What should be the distance between sample and TeraSpike microprobe?
A: The distance between the microprobe tip and the device under test should usually be approx. in the range of the targeted resolution.
Q: What should I watch for regarding the optical probe beam alignment to the microprobe?
A: The probe beam has to stay focused and stable on the photo-switch of the microprobe during the measurements. For probe beam alignment you should use the photocurrent under applied bias voltage as a feedback signal.
Q: Is there a preferred side of the microprobe cantilever for the optical probe beam excitation?
A: The recommended microprobe orientation and the range of laser beam excitation angles are given in our application notes (PDF file). The highest photocurrent for a given excitation power is achieved from the cantilever back-side. An optical excitation from the top-side of the cantilever (carrying the electrode structures) is possible as well, but will result in a decreased photo-current.
Q: How sensitive are the microprobes to vibration? Will I need a vibration isolation?
A: Even at very short microprobe-to-sample distances a standard optical table with standard vibration isolation is usually sufficient to make undistorted measurements. However, vibration sources should not be placed on the optical table directly if possible. Mechanical choppers are usually uncritical, as long as there is a sufficient distance to the microprobe.
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