Rolf Clauberg

High electron density effects in electron spectroscopies: Consequences for picosecond photoemission and electron‐beam sampling

High electron density effects on photoyield and electron energy distributions have become important in several electron spectroscopies and in electron microscopy since the availability of high‐intensity photon and electron sources. In this work we show that such effects also lead to limitations in voltage sensitivity and time resolution in photoemission and electron‐beam sampling measurements of voltage signals if picosecond time resolution is required. The influence of high electron densities in picosecond pulses for these methods is analyzed theoretically and compared with experimental results in photoemission sampling. It is shown that the space‐charge limitation to the number of electrons per pulse which can be emitted from a sample and the energy broadening of the pulse owing to the Coulomb repulsion between the electrons impose significant limitations on the voltage sensitivity of photoemission sampling and of electron‐beam sampling with a pulsed high‐intensity cathode. Also the time resolution is d...

Beam properties of AlGaAs power lasers with high-quality etched mirrors

High-quality etched mirrors for AlGaAs/GaAs power lasers for applications in optical storage have been fabricated by chemically assisted ion-beam etching (CAIBE). In order to ensure flat mirror facets of the ridge-waveguide lasers, a flared-waveguide end section is used. This results in a very slight mirror roughness of approximately 20 nm across the beam cross section, and yields excellent beam properties allowing diffraction-limited focusing up to 50-mW output power.<<ETX>>

Microfields in stroboscopic voltage measurements via electron emission. I. Response function of the potential energy

It is shown that the response of the electrostatic potential on voltage changes at a conducting line in a microscopic structure is fully described by a pure geometry function. This function is determined by the special microscopic character of the conducting line and by the screening due to neighboring conductors. It already allows a qualitative description of transit‐time and cross‐talk effects in voltage measurements via electron emission or electro‐optical sampling, and provides a basis for the quantitative calculation of these effects. The geometry dependence of this function will be analyzed in detail.

A scalable SDH/SONET framer architecture for datacom and telco applications

This paper presents the architectural concepts behind a versatile VLSI device that maps ATM, IP, and/or traditional T1/T3 traffic streams into SONET/SDH transport signals ranging from OC-1 to OC-48/STM-16. Additional key features for effective system integration are on-chip support for add-drop multiplexing, digital cross-connect, and automatic protection switching functions. A roadmap discussing the applicability of the developed concepts for next-generation framers up to OC-192/STM-64 is also presented.

Energy and time-resolved photoemission in a promising new approach for contactless integrated-circuit testing

Abstract A novel approach to contactless measurement of voltages on internal nodes of integrated circuits is presented. The method is based on time-resolved photoemission exploiting the single-photon process with short laser pulses in the ultra-violet. The method allows spatial resolution in the submicron range given by the diffraction limit for UV photons, a time resolution of a few picoseconds given by the width of the laser pulses and the electron transit-time effect, and a voltage resolution of a few microvolts within a signal integration time of one second.

Photoemission sampling technique for high-speed integrated-circuit testing

After a short review of the basic principles of time-resolved photoemission and its capabilities as a method for contactless electrical testing of integrated circuits, this paper reports on the progress made toward meeting the requirements for integrated-circuit (IC) testing and diagnostic equipment. The goals of IC testing are to provide high time and voltage resolutions with short testing time, and simultaneously high spatial resolution independent of the circuit technology (Si, GaAs). Here, the emphasis is on the time and voltage resolutions and short testing time. In the photoemission process, these parameters are independent of the spatial resolution in the regime of interest. The investigation is carried out with a pulsed-laser system generating picosecond pulses in the UV range. The measurements presented were performed on photoconductive switches. This allows testing the time resolution of the method by ultra-fast signals, and generating the electric transients to be sampled by the same laser source as the sampling pulse, guaranteeing almost jitter-free operation. The results clearly demonstrate that photoemission sampling is capable of contactless diagnostics and testing of very high-speed circuits with a high-voltage resolution and short testing time.

Microfields in stroboscopic voltage measurements via electron emisson. II. Effects on electron dynamics

In this article, the transit‐time and cross‐talk effects occurring in voltage measurement via electron emission are analyzed as a function of geometry, extraction fields, electron start energies, and rise times of the actual input signals. The investigation was performed to obtain information about the maximum achievable time resolution and the disturbance of measured signals by cross‐talk effects in corresponding contactless measurement techniques like photoemissive sampling and electron‐beam probing. The field distribution above the sample was assumed as being two‐dimensional, and the influence of space‐charge effects neglected. A strong correspondence to the purely geometry‐dependent response function of the potential energy, analyzed in Part I [J. Appl. Phys. 62, 1553 (1987)], is established.

High-Speed Integrated Circuit Testing by Time-Resolved Photoemission

The growing complexity of integrated circuits (IC) and the rapid development in VHSICs require contactless testing methods for logic state analysis and waveform measurements on internal nodes of VLSI chips. Considering the fast evolution of VLSI/VHSIC technologies, a contactless testing method has simultaneously to provide challenging features like high-voltage resolution (mV), high spatial resolution (sub-micrometer), and high time resolution (ps) in a short testing time. In addition to these requirements, it is desired that the method should be applicable to all technologies, e.g., Si as well as GaAs-based ones.

Design methodology for a large communication chip

The example chip operates with 14 externally provided system clocks plus four clocks recovered from input data streams and 36 corresponding internal clock domains, it also couples a large digital design to a mixed-signal part in physical design.

Photoemission sampling measurements of a dispersing voltage pulse traveling on a transmission line

The newly developed method of photoemission sampling, based on the single‐photon process, has been applied to measure the dispersion of a picosecond voltage pulse traveling on a transmission line. The dispersion of the propagating pulse is clearly revealed in the spectra which show signal rise times of about 17 ps at 2 mm away from the pulse generating switch, and change into rise times of about 30 ps at 1.5 mm further away. The time resolution of the measurements is better than 7 ps. Therefore, photoemission sampling with picosecond laser pulses permits the measurement of changes in signal waveforms at arbitrary points of a transmission line and for arbitrary substrate materials with sufficient time resolution.