Massachusetts Institute of Technology

Sean R Bishop

Harry L Tuller

Krystyn J Van Vliet

Jae Jin Kim

James F Smith

Jessica G Swallow

Current techniques for measuring chemical expansion in thin film structures are too slow, too imprecise, or require synchrotrons. In contrast, nanoscale electrochemomechanical spectroscopy (NECS) can be used to make nanoscale measurements at time scales of seconds with simple contact or non-contact sensors. In a NECS measurement, a sample, such as thin-film oxide structure, is subjected to a temporally modulated stimulus, such as a sinusoidally alternating voltage. The stimulus causes the sample to expand, contract, deflect, or otherwise deform. A sensor, such as a contact probe or optical sensor, produces an electrical signal in response to this deformation that is correlated with the temporal modulation of the stimulus. Because the stimulus and deformation are correlated, the temporal modulation of the stimulus can be used to filter the deformation signal produced by the sensor, producing a precise, sensitive measurement of the deformation.

Frequency-based detection of chemical expansion dynamics in thin films

Radiation detector. The detector includes an ionic junction having an ionically bonded wide band gap material having a first region dominated by positively charged ionic defects in intimate contact with a second region dominated by negatively charged ionic defects forming depleted regions on both sides of the junction resulting in a built-in electric field. The detector also includes an ionic junction having a first ionically bonded wide band gap material dominated by positively charged ionic defects in intimate contact with a second ionically bonded wide band gap material dominated by negatively charged ionic defects forming depleted regions on both sides of the junction resulting in a built-in electric field. Circuit means are provided to establish a voltage across the junction so that radiation impinging upon the junction will cause a current to flow in the circuit.

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Silver Spring, MD, United States of America

Sean R Bishop