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54 SMT007 MAGAZINE I OCTOBER 2018 from active flux residues, insufficient hole fills, and ineffective cleaning, among other issues. I want to reiterate that I am not saying all fail- ures are related to those working the third shift, but these problems seem to be commu- nicated to quality managers or documented for future reference less often. When a failure comes back to an internal or external lab for inspection, it is much easier to diagnose the root cause if the full process is communicated and documented. With a fully documented procedure from the kitting process to final packaging, you can communi- cate in a language of reliability. SMT007 Eric Camden is a lead investigator at Foresite Inc. To read past columns or contact Camden, click here. Scientists from the Femtosecond Spectroscopy Unit led by Prof. Keshav Dani at the Okinawa Institute of Science and Technology Graduate University (OIST) have demonstrated a new mechanism that can potentially allow the control of electrons on the nanometer spatial scale and femtosecond temporal scales using light. The study has been published in the journal Science Advances. Dr. E. Laine Wong, a recent PhD graduate at OIST, and her colleagues have used a physical phenomenon called surface photovoltage effect to induce electric fields on the material surface, allowing them to direct electrons to flow in opposite directions. "By making use of the nonuniform intensity profile of a laser beam, we manipulate the local surface potentials to create a spatially varying electric field within the photo- excitation spot. This allows us to control electron flow within the optical spot," says Dr. Wong. Using a combination of femtosecond spectroscopy with electron microscopy techniques, Dr. Wong and her colleagues made a movie of the flow of electrons on femtosecond timescales using a technique known as pump-probe spectroscopy, allowing them to study the dynamics of the excited electrons at a very short time scale. The combination of an electron microscope then further provides the scientists with the spatial resolution required to directly image the movement of the excited electrons even within the small area of the laser beam spot. The findings of the study are promising to control the movement of electrons beyond the resolution limit of light by utilizing the spatial intensity variations of the laser beam within the focal spot. The mechanism could therefore be potentially used to operate nanoscale elec- tronic circuits. Prof. Dani and his team are now working towards building a functional nanoscale ultrafast device based on this newfound mechanism. (Source: Okinawa Institute of Science and Technology Graduate University) Study Demonstrates New Mechanism for Developing Electronic Devices

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