TERAHERTS DETECTORS BASED ON CMOS FIELD-EFFECT TRANSISTORS

The investigations focusses on the exploration of plasma-wave dynamics excited within the channel of sub-micrometer long field-effect transistors. Besides of fundamental interest, the phenomenon enables development of low-cost terahertz (THz) camera solution utilizing the main stream approach in the development of the semiconductor technologies: CMOS field-effect transistors as detectors, with inherent advantages with respect to the integration and lower power consumption.

SPECTRAL AND CORRELATION ANALYSIS FOR RELIABILITY AND LIFETIME ASSESSMENTS OF HBT AND HEMT TRANSISTORS

The research is being carried out in order to create a fast, unharmful and reliable method in clearing up transistors' reliability, quality and lifetime.

Low frequency noise analysis enables us to evaluate the defectiveness and reliability of semiconductor devices.

Low frequency noise correlation analysis gives additional information on physical processes that take place in devise structure. Cross-correlation between transistors' base current fluctuations and emitter current fluctuations is measured. The experimental data are used in order to determine whether the parameter could be used for reliability assessments of the device.

Modelling of transistors equivalent noise circuit and prediction of noise mechanisms prevailing in transistors of different design is a point of interest, too.

SPECTRAL AND CORRELATION ANALYSIS FOR RELIABILITY AND LIFETIME ASSESSMENTS OF OPTOELECTRONIC DEVICES: LIGHT EMITTING DIODES AND SEMICONDUCTOR LASER DIODES

Low frequency noise characteristic measurements, spectral and correlation analysis clear up physical processes in various optoelectronic structures, enables finding out causes of device degradation, plays into evaluation of quality, reliability and lifetime. Noise characteristics of optoelectronic devices comprise of optical (light output power fluctuation) and electrical (terminal voltage fluctuation) noise signals and cross-correlation factor between them. Different wavelength (visible light, infrared, ultraviolet, white light) and material (InGaAs, InPGaAs, GaN, InGaN) light emitting diodes, telecommunication (1,35 µm and 1,5 µm) and long wavelength (3 µm – 5 µm) laser diodes are under investigation.

NOISE AND PHOTOSENSITIVITY CHARACTERISTICS OF HIGH-SPEED AVALANCHE/PIN PHOTODETECTORS

Low frequency noise spectroscopy, noise distribution in the active area and photosensitivity measurements, excess noise factor and ionization ratio measurements and evaluation. Unique microscopy setup enables us to measure photosensitivity distribution across the photodetectors active surface with a 1nm/1μm resolution (depending on wavelength of the light source). Such measurements enable detection of defective areas of the photodetector and provide solutions for the improvement of the fabrication of the device.

MEASUREMENT OF PULSE CHARACTERISTICS OF LIGHT EMITTING AND LASER DIODES

High frequency noise investigation of output power fluctuations of lasers and LEDs and evaluation of main dynamic characteristics and their scattering.

FLUCTUATION PHENOMENA IN BIOLOGICAL SYSTEMS

Blood circulation system guarantees vitality of the human body. Malfunction of this system often occurs unawares and endangers to the human life. Therefore development of new diagnostic methods is really actual nowadays.

Blood circulation system generates various signals (electric, acoustic) that carry considerable information on the system state. But nowadays used common methods are unable to detect all changes of the system state. Cardiovascular system function consists of quasiperiodic events sequence. Periodicity of the events is controlled by autonomous regulatory systems and random external factors. Consequently the signal consists of periodic (deterministic) and random (noise) components. It is well known that noise characteristic investigation in physics, mechanics etc. gives valuable information on system state. Therefore investigation of noise characteristics of cardiovascular system signals can also give valuable information. The investigations are focused on clearing up the features of fluctuation of signals generated by human cardiovascular system that enable comprehensive evaluation of the cardiovascular system state and detection of changes of that state in the initial stage.