Laser-induced Transients Research Articles

Analysis of Single Event Transients in Arbitrary Waveforms Using Statistical Window Analysis

Window or taper functions are commonly used in data processing to detect transient events or for time-averaging of frequency spectra. A generalized window function is demonstrated using the Ionizing Radiation Effects Spectroscopy (IRES) technique to enhance the measurement of transient anomalies within arbitrary waveforms. The IRES filter is used to convolve time data with a sliding window consisting of a moment-generating function. The resulting time-dependent statistical moments can be used to eliminate any steady-state signatures, including noise, and extract transient behaviors. The IRES filter is used to analyze data from heavy-ion exposures of commercial off-the-shelf (COTS) operational amplifiers, laser-induced transients in CMOS phase-locked loops, and simulated transients in digital and analog circuits. The performance of the IRES filter in noisy environments shows that transients can be measured with higher fidelity than standard amplitude thresholding. This statistical window analysis technique may remove the need for complex triggering mechanisms on instrumentation and does not require <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">a-priori</i> knowledge of transient characteristics. Potential applications of IRES include real-time measurement, <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">in-situ</i> data analysis, and machine learning.

Temperature effects on platinum single-crystal electrodes

This work reviews three different approaches for the study of temperature effects on the platinum single-crystal | solution interphase. First, the method of analysis of temperature-dependent voltammetric data with the help of a generalized isotherm is described and illustrated for the case of adsorbed hydrogen and OH species on Pt(111) in 0.1 M HClO4. This method of analysis allows a detailed evaluation of the thermodynamic data of charge-transfer adsorbed species, namely, the standard molar Gibbs energy, enthalpy and entropy of adsorption and the magnitude of the lateral interaction between adsorbed species. However, a number of assumptions are involved in the application of a generalized isotherm, namely, the assumption of a Langmuirian configurational term and an arbitrary separation of capacitive and faradaic processes. The second approach described here overcomes these assumptions, since it employs Gibbs thermodynamic equations for interphaces to describe temperature effects on electrosorption processes including those in which charge-transfer is allowed. This approach allows evaluation of the entropy of formation of the interphase, being defined as the difference in entropy of the components of the interphase when they are forming it and when they are in the bulk phases. This method of analysis is illustrated through the evaluation of the entropy of formation of the interphase for Pt(111) in 0.1 M HClO4. Finally, it is shown that temperature effects on interfacial processes can also be studied by means of the application of a fast temperature perturbation. This approach opens the possibility to separate the effect of temperature on the different components of the interphase. The fast temperature perturbation is usually achieved with short laser pulses, and hence the method is called the laser-induced temperature jump method. This approach is illustrated here for the case of Pt(111) in 1 mM HClO4 + 0.1 M KClO4, and it is shown that the corresponding laser-induced transients provide direct evidence on the reorientation of the interfacial water network.

Evaluating the Influence of Various Body-Contacting Schemes on Single Event Transients in 45-nm SOI CMOS

We investigate the single-event transient (SET) response of T-body and notched-body contacted MOSFETs from a commercial 45 nm SOI RF-CMOS technology. Although body-contacted devices suffer from reduced RF performance compared to floating body devices, previous work on 65 nm and 90 nm MOSFETs has shown that the presence of a body-contact significantly mitigates the total ionizing dose (TID) sensitivity that is exhibited in floating-body SOI MOSFETs. The influence of body-contacting schemes on the single-event effect (SEE) sensitivity is examined here through time-resolved measurements of laser and microbeam-induced transients from T-body and notched-body MOSFETs. Laser-induced transients demonstrate the reduced SEE sensitivity of the notched-body MOSFETs as compared to the T-body MOSFETs; this is evidenced by a uniform reduction in the peak transient magnitudes and collected charge for transients captured at the worst-case bias of VDS = 1.0 V, as well as with all terminals grounded. Microbeam-induced transient data are also presented to support the validity of the laser-induced transient data. Together, these data provide new insight into the RF versus TID versus SEE tradeoffs associated with body contacting schemes in nm-scale MOSFETs, an important concern for emerging space-based electronics applications.

Effects of Ionizing Radiation on Digital Single Event Transients in a 180-nm Fully Depleted SOI Process

Effects of ionizing radiation on single event transients are reported for Fully Depleted SOI (FDSOI) technology using experiments and simulations. Logic circuits, i.e. CMOS inverter chains, were irradiated with cobalt-60 gamma radiation. When charge is induced in the n-channel FET with laser-probing techniques, laser-induced transients widen with increased total dose. This is because radiation causes charge to be trapped in the buried oxide, and reduces the p-channel FET drive current. When the p-channel FET drive current is reduced, the time required to restore the output of the laser-probed FET back to its original condition is increased, i.e. the upset transient width is increased. A widening of the transient pulse is also observed when a positive bias is applied to the wafer without any exposure to radiation. This is because a positive wafer bias reproduces the shifts in FET threshold voltages that occur during total dose irradiation. Results were also verified with heavy ion testing and mixed mode simulations.

Temperature Dependence of Spatially Resolved Picosecond Laser Induced Transients in a Deep Submicron CMOS Inverter

Spatially-resolved picosecond laser induced transients have been measured in a 0.18 mum CMOS inverter test structure as a function of temperature. Sensitive <i xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">n</i> -drain and <i xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">p</i> -drain nodes have been scaled in size to accommodate characteristic differences between ion and laser tracks. Images based on pulse characteristics have been collected from 325 K to 400 K and transient currents extracted from laser strikes to both the OFF drain and its surroundings. With increasing temperature strikes to the OFF drain result in a pulse width which appears to broadens whilst the charge collected surprisingly decreases.

Potential-dependent water orientation on Pt(1 1 1) stepped surfaces from laser-pulsed experiments

Coulostatic potential transients induced by nanosecond pulsed laser irradiation on Pt(1 1 1) stepped surfaces in perchloric acid solutions are analyzed here. The results provide unique information on the effect of the structure of the metal surface on the potential-dependent water reorientation at the electrified interphase. The most significant information is obtained from the sign and shape of the laser-induced transients. The existence of two potentials where the transient is zero can be related to the local properties of the surface, i.e. the existence of two local potentials of zero free charge, corresponding to the step and terrace sites. The dependency of these quantities with the step density is studied in detail. In addition, it is found that the presence of steps significantly slows down the coulostatic response at potentials in the double-layer region, which has been interpreted as a decrease in the velocity of water reorganization. The corresponding relaxation time is estimated and its dependency with the step density is also analyzed.

Andrew Ching Tam

Andrew Ching Tam, an IBM research scientist who was a pioneer and internationally respected expert in the field of laser-induced photoacoustic and photothermal phenomena, died peacefully at a hospital in San Jose, California, on 23 February 2001 after a massive stroke.Andrew was born on 13 October 1944 in Fushan, which is in the province of Canton, China. His potential was recognized early in his career. He entered the University of Hong Kong in 1964 as a Hong Kong Government Scholar. He received his BS in physics and mathematics there in 1967, a BS with a specialization in physics in 1968, and his MPhil in physics in 1970.In 1970, Andrew enrolled in graduate school at Columbia University. After receiving his PhD in 1975 for his work in atomic, molecular, and laser physics, he was appointed an assistant professor of physics. His impressive scientific creativity became apparent at Columbia. Two of his important discoveries are the first magnetic resonance imaging experiment in laser-polarized sodium vapor, and “laser snow,” clouds of alkali-hydride crystals formed when resonant light is absorbed by alkali-metal vapors in hydrogen gas.In 1978, Andrew joined Bell Laboratories in Murray Hill, New Jersey, as a member of the technical staff. There, he pioneered the detection of laser-induced acoustic transients with ultrasound transducers and made numerous contributions to the emerging field of photoacoustic or optoacoustic spectroscopy. Using these techniques, he demonstrated the capability of ultrasmall optical absorption measurements in solid, liquid, and amorphous media in the presence of large scattering losses. His energy and skill at attacking new problems successfully were legendary at Bell Labs.After joining IBM’s San Jose Research Laboratory (now the IBM Almaden Research Center) in 1979, Andrew expanded the scope of his work to include transient thermal processes. He constantly pushed the detection limits of these techniques to higher time resolution and greater sensitivity to explore the spectral, thermal, and acoustical properties of materials of scientific and technical interest. With ever higher laser-induced temperature transients, he studied the thermal properties of these materials during laser-induced melting, vaporization, and ablation. More than 150 publications in the scientific literature are a permanent record of his work in photothermal phenomena.In parallel, Andrew pursued applications of these phenomena in the computer industry. This aspect of his work resulted in 38 US patents, which focused on texturing the head-parking zone of magnetic hard disks. In 1995, he developed a technique to roughen the supersmooth disks in a well-controlled fashion to prevent a Van der Waals interaction from irreversibly joining the magnetic read/write element with the recording media when a disk drive is powered down. Andrew not only studied the underlying physics in great detail, but also developed the manufacturing tools and the diagnostic procedures that made his texturing process a success throughout the industry. In 2000, he was the manager of exploratory magnetic recording processes at IBM Almaden.Andrew’s other notable industrial contributions included the development, in 1987, of high-power laser techniques for stripping the insulation off delicate wires—with diameters smaller than a human hair—used to connect disk drive recording heads to the rest of the drive and to clean submicrometer dust particles from lithography masks (1991).In early 2001, Andrew received an Engineering Excellence Award from the Optical Society of America for his development of laser-based manufacturing processes for the disk drive industry. Andrew was active in professional societies and involved in creating scientific exchanges within his field. As a conference organizer, he offered enthusiastic support and an intimate knowledge of the physics and physicists involved. He was instrumental in starting and organizing a series of international conferences on photoacoustic and photothermal phenomena and the corresponding Gordon Conferences. Those who listened to his intense and very outspoken lectures will never forget them. His colleagues admired his drive, his experimental skills, his deep understanding of the physical phenomena involved in laser-induced transient heating, and his skill in applying those phenomena to solve critical technological problems.Andrew also was a passionate cook, a charming host, and a great friend and companion to those people who got to know him. His career reminds us of the laser pulses that he used so successfully: bright, intense, and short—unfortunately, too short. Andrew Ching Tam IBM ALMADEN RESEARCH CENTERPPT|High resolution© 2001 American Institute of Physics.

Measurement of tissue optical properties by time-resolved detection of laser-induced transient stress

We report on a technique utilizing time-resolved detection of laser-induced stress transients for the measurement of optical properties in turbid media specifically suitable for biological tissues. The method was tested initially in nonscattering absorbing media so that it could be compared with spectrophotometry. The basis of this method is provided by the conditions of temporal stress confinement in the irradiated volume where the pressure generated in tissues heated instantly by laser pulses is proportional to the absorbed laser energy density, and the exponential profile of the initial stress distribution in the irradiated volume corresponds to the z-axial distribution of the absorbed laser fluence. Planar thermoelastic waves can propagate in water-containing media with minimal distortion, and their axial profiles can be detected by an acoustic transducer with sufficient temporal resolution. The acoustic waves induced by 14-ns laser pulses in nonscattering media, turbid gels, and tissues were measured by a piezoelectric transducer with a 3-ns response time. Temporal profiles of stress transients yielded z-axial distributions of the absorbed laser energy in turbid and opaque media, provided that the speed of sound in these media was known. The absorption and effective scattering coefficients of beef liver, dog prostate, and human aortic atheroma at three wavelengths, 1064 nm (in near infrared), 532 nm (visible), and 355 nm (near UV), were deduced from laser-induced stress profiles with additional measurements of total diffuse reflectance.

Laser-induced transients in coupled doppler-broadened systems

Laser-induced transients in coupled doppler-broadened systems

Laser-induced acoustic breakage of tobacco mosaic virus.

CAROME, in a recent letter1 commenting on our article on the mechanical disruption of tobacco mosaic virus2 by laser-induced transients, suggests that the effect we detected may have been caused by a number of complicating factors related to pulse reflexions and/or cavitation of the suspending medium. Although the points made by Carome are certainly valid we would like to clarify the issue. We obtained TMV breakage in all of the cases mentioned by Carome; namely, pulses reflected back through the liquid sample at a water-to-air interface; or totally transmitted without reflexion; or transmitted into a finite thickness water layer and then reflected at a water–air interface. The fact that breakage was obtained with totally transmitted pulses, which corresponds to transmission of a positive pressure transient through the virus suspension, is particularly important. As mentioned in our previous communication2, the effect was enhanced when the reflexions occurred at the liquid–air interface of the virus suspension. Breakage was not, however, significantly increased by reflexions (including negative transients) generated at other interfaces in the system. The details of the hydrodynamical analysis of the stress engendered in the TMV by the laser-induced acoustic transient have been presented in greater detail elsewhere3.