Application highlights, research results and product news around photoconductive THz near-field microprobes — from in-line semiconductor metrology to graphene, quantum materials and biosensing.
Samsung Electronics researchers used Protemics’ photoconductive near-field microprobes for the first in-line near-field THz time-domain spectroscopy inside a memory fab — measuring tungsten film properties and gate-oxide interface nitridation at sub-10 µm resolution, without contact and without destroying the wafer.
Samsung Electronics researchers used Protemics’ photoconductive near-field microprobes for the first in-line near-field THz time-domain spectroscopy inside a memory fab — measuring tungsten film properties and gate-oxide interface nitridation at sub-10 µm resolution, without contact and without destroying the wafer.
Researchers from Sungkyunkwan University, MIT and the University of Minnesota combined field-enhancing resonators with THz near-field imaging on a TeraCube system. Their “STRING” approach reads out a single resonator instead of a large ensemble — about ten orders of magnitude more sensitive than far-field THz measurements on pelletized samples.
With a TeraCube M2 THz near-field scanner, B. C. Park et al. (Sungkyunkwan University) imaged and controlled chiral-anomaly-induced currents in the topological Dirac semimetal KZnBi on picosecond time and micrometre length scales — reported in Science Advances.
The Florida Institute for Cybersecurity Research (FICS) installed a TeraCube M2-R reflection-mode THz near-field scanner to detect security-relevant modifications in integrated circuits and chip packages non-destructively.
THz near-field imaging of plants reaches the single-cell level
The THz range is highly sensitive to water content and to characteristic biomolecule absorption lines. Researchers at Jilin University, together with the Chinese Academy of Sciences, used a TeraSpike microprobe for the first in-situ THz near-field imaging of single plant cells.
Graphene ink layers for flexible electronics mapped with contactless THz microprobes
Printed and spray-coated graphene inks are promising for flexible electronics, but layer inhomogeneity remains a key issue. A joint study by RWTH Aachen University, AMO and Protemics used THz microprobe conductivity mapping over large samples to show how surface morphology governs the uniformity of graphene ink layers.
Mapping photo-excited carrier dynamics in wafers with a TeraSpike probe
TeraSpike probes are widely used to map wafer sheet resistance and carrier mobility. Researchers at DIFFER and Eindhoven University of Technology extended this to wafers under short-pulse optical excitation: they mapped carrier relaxation at a resolution ten times finer than the THz wavelength, from ultrafast to slow trapping processes.
Laser Focus World: “Terahertz imaging tackles solar cell and semiconductor process inspection”
The October 2017 issue of Laser Focus World featured Protemics’ THz microprobe technology in inspection applications, including a TeraCube near-field imaging system operated with a fiber-based time-domain spectroscopy module.
Metamaterials caught in the act: enhanced electromagnetically induced transparency verified in the near field
Halpin et al. (DIFFER, Eindhoven) showed that electromagnetically induced transparency can be enhanced without hard-to-fabricate, narrowly spaced structures — by tuning the long-range lattice coupling of periodic metamaterials to the metamolecule resonances. The behaviour was verified with a TeraSpike TD-800-X-HR near-field probe.
TeraSpike TD-800-TR.5: the first near-field transceiver probe for reflection-mode measurements
Two closely spaced photoconductive antennas — one emitter, one detector — on a single slim probe, with wave-trap electrodes and the flexible XR cantilever. It gives sub-wavelength resolution and the shortest THz paths on large, complex or THz-opaque samples such as solar cells, buried laser welds and fiber-reinforced materials.
SHG-Unit: run LT-GaAs microprobes with 1550 nm femtosecond fiber lasers
The nonlinear-optical SHG-Unit frequency-doubles 1500–1600 nm pulses into the 750–800 nm range, so cost-efficient telecom-wavelength fiber lasers can excite LT-GaAs-based TeraSpike microprobes. Available with free-space or fiber-coupled input.
Terahertz waves beware — it’s a trap: wave-trap option for TeraSpike probes
Under some conditions an incident THz wave couples into the planar waveguides of the probe tip and creates “ghost” reflections in long time-domain traces. The WT electrode design slows down and absorbs these waves in a resistive sub-wavelength layer.
A team led by Prof. Jaime Gómez Rivas (AMOLF) quantified with a TeraSpike TD-800-X-HRS microprobe that resonant structures can oscillate most strongly in the near field at a markedly different frequency than far-field spectroscopy suggests — essential knowledge for resonant sensors.
First automated THz microprobe wafer analysis system for solar cells launched at ECN
Built by Protemics in cooperation with the Energy research Centre of the Netherlands (ECN), the tool maps sheet resistance over full solar-cell areas at a resolution of a few tens of micrometres and up to 3 ms per measurement point — also on rough, bent or passivated samples.
Invisible anti-counterfeiting labels read out by THz sheet resistance imaging
With Rolith, Inc., Protemics demonstrated the read-out of covert security labels written into transparent NanoWeb® metal-mesh conductors. Invisible to the eye and to optical microscopes, the logo appears in a THz microprobe map of the sheet resistance.
In a study by Protemics and Fraunhofer ILT, TeraSpike near-field imaging detected micron-scale air voids and inhomogeneities in laser weld seams of optically opaque polymers such as polypropylene, polyamide and fiber-reinforced plastics — non-destructively.