Koichiro Takeuchi

High‐speed optical sampling measurement of electrical wave form using a scanning tunneling microscope

The optical sampling measurement of a high‐speed electrical wave form using a scanning tunneling microscope (STM) is demonstrated. An optical pulse train from a laser diode (LD) is used to turn on and off a photoconductive switch on a STM probe to measure a signal from a Schottky barrier diode (SBD) in a sampling procedure. A time resolution less than 300 ps has been achieved. This novel method has the potential to create a breakthrough in ultra‐high‐speed wave form measurement through this unique combination of optical sampling and STM technology.

Application of scanning tunneling microscope to high-speed optical sampling measurement

A novel method for a measurement of a high-speed electrical waveform using a scanning tunneling microscope (STM) is demonstrated. An optical pulse train is used to turn on and off the photo-conductive switch on the STM probe to measure a high-speed signal in an equivalent sampling procedure. The temporal resolution of 160 ps has been achieved. This method has the potential to create a breakthrough in ultra high-speed waveform measurement through this unique combination of optical sampling and STM technology.<<ETX>>

Image observation of pico second electrical pulse by scanning force optoelectronic microscope

We succeeded for the first time in visualizing instantaneous voltage distribution of 2ps electrical pulse propagating on coplanar strips (CPS). This result was obtained using a scanning force optoelectronic microscope (SFOEM) which we have developed by coupling a scanning force microscope (SFM) and an ultrafast optical sampling technique. The observed voltage distribution shows a single peak deviating outward. The result seems not consistent with a simple theoretical prediction. There is a possibility that simple theoretical treatments usually used are no more useful for calculating ultrafast pulse distribution.

Picosecond pulse propagation images and oppositely polarized pulse shapes on CPS lines measured by a Scanning Force Optoelectronic Microscope

We have developed a novel ultra-fast voltage measurement system, the scanning force optoelectronic microscope (SFOEM), by integrating a scanning force microscope (SFM) and an optical sampling technique. This paper describes a method by which a 2ps pulse propagation image directed along the edge of a coplanar strip (CPS) has been recorded using the SFOEM. It also describes how oppositely polarized pulses on each line of the CPS were measured by the SFOEM. These results demonstrate that the SFOEM is a useful tool not only for measuring ultra-fast voltage and pulse propagation images but also for analyzing the operation of ultra-fast LSI devices.

2ps electric pulse measurement using scanning tunneling/force optoelectronic microscope

We have developed new measurement systems for ultrafast electric signals using a STM (scanning tunneling microscope) and a SFM (scanning force microscope). A photo-conductive semiconductor switch (PCSS) on the probe is used as a sampler in an optical sampling procedure. We measured electric pulse with 2.5 ps width that corresponds to a time resolution better than 2 ps. This substantial improvement was realized by using low temperature grown GaAs for the PCSS and by decreasing the probe dimension.