Cezary Sydlo

Model for the decrease in HBT collector current under DC stress based on recombination enhanced defect reactions

Abstract Based on simplifying assumptions a model is developed to describe decreasing HBT collector current under DC bias stress. The underlying processes are recombination enhanced defect reactions (REDR), namely defect generation and defect annealing. The simplification of the derived equation under particular boundary conditions leads to a form of the Eyring relationship generally employed to describe the decrease in collector current under DC bias stress. Additionally, pulsed tests with an emitter current density of JE=200 kA/cm2 have been performed. The comparison between measured data from these tests and their fit proofs the applicability of the derived equation. Of course this can not be an evidence for the real running physical processes.

A method for HBT process control and defect detection using pulsed electrical stress

Abstract A method for on-wafer reliability characterisation of HBT processes is developed to reveal lifetime deficiencies. Lifetime limiting defects can be generated to investigate the lifetime quality by applying Transmission Line Pulses MP) to the device. Very high current densities can be used to shorten the time of electrical defect generation, while the pulse length is short compared to the thermal time constant of the device. Current and voltage of impulse response and subsequent DC I/V measurements are used for device characterisation between each step of stress which consists of a variable pulse quantity.

Design and Operation of the Integrated 1.3 GHz Optical Reference Module with Femtosecond Precision

In modern Free-Electron Lasers like FLASH or the European XFEL, the short and long-term stability of RF reference signals gains in importance. The requirements are driven by the demand for short FEL pulses and low-jitter FEL operation. In previous publications, a novel, integrated Mach-Zehnder Interferometer based scheme for a phase detector between the optical and the electrical domain was presented and evaluated. This Laser-to-RF phase detector is the key component of the integrated 1.3GHz Optical Reference Module (REFM-OPT) for FLASH and the European XFEL. The REFMOPT will phase-stabilize 1.3GHz RF reference signals to the pulsed optical synchronization systems in these accelerators. Design choices in the final hardware configuration are presented together with measurement results and a performance evaluation from the first operation period in the European XFEL.

Custom Optomechanics for the Optical Synchronization System at the European XFEL

Free-electron-lasers like the upcoming European XFEL demand highly reliable optical synchronization in the range of a few femtoseconds. The well-known optical synchronization system at FLASH had to be reengineered to meet XFEL requirements comprising demands like ten times larger lengths and raised numbers of optically synchronized instruments. These requirements directly convert to optomechanical precision and have yielded in a specialized design accounting for economical manufacturing technologies. These efforts resulted in reduced spatial dimensions, improved optical repeatability, maintainability and even reduced production costs. To account for thermal influences the heart of the optical synchronization system is based on an optical table made out of SuperInvar. To fully exploit its excellent thermal expansion coefficient, mechanical details need to be taken into account. This work presents the design and its realization of the re-engineered optomechanical parts of the optical synchronization system, comprising mounting techniques, link stabilization units and optical delay lines for high drift suppression.

Fully Monolithically IntegratedWide-Band RF-Source

A highly integrated wide-band MMIC RF-source using the heterodyne frequency conversion scheme is presented in this paper. Two oscillators, a mixer, and three corresponding buffer amplifiers find place on a MMIC chip with dimensions of 3.0 × 1.8mm2 manufactured using a commercially available 0.25 ¿m pHEMT process. The circuit provides RF power within a wide range of f = 3.5 - 6.5GHz.