Characterization of Optical and Photoelectrical Properties of ZnO Crystals

We characterized optical and photoelectrical properties of undoped and Ga-doped ZnO layers differently grown on sapphire substrates by using complementary optical methods. Different stimulated emission threshold values for ZnO epitaxial layers grown by pulsed laser deposition and MBE methods were attributed to crystalline quality of the layers and the growth method used. Different carrier lifetimes in various ZnO epitaxial layers are explained by defect-related and intrinsic mechanisms of recombination

Алгоритм выбора точки интерконнекции распределенной генерации и ее интеграция в работу энергосистемы

В статье представлен алгоритм выбора точки интерконнекции распределенной генерации с учетом поставленных критериев. Рассмотрены основные факторы, влияющие на режимы работы энергосистемы в зависимости от точки интерконнекции источников распределенной генерации

Experimental studies of light-microwave field interaction and nonequilibrium carrier transport in GaAs

Contactless nonlinear optics and microwave techniques are combined to study nonequilibrium carrier transport and photoelectric properties of GaAs crystals in electric fields. Peculiarities of complex diffusion-drift processes of photoexcited carrier plasma under microwave heating.and fast transients of carrier transport in space-charge internal electric field are analysed by measuring orientational, temporal and field dependences of light diffraction on light-induced transient grating

DEVELOPMENT OF NOVEL OPTICAL TECHNIQUES AND DEVICES FOR NON-DESTRUCTIVE CHARACTERIZATION OF SEMICONDUCTING COMPOUNDS AND STRUCTURES (SfP 974476)

NATO 'Science for Peace' Project (Years 2000-2005). Scope: A principal goal of the project was the development of novel optical (holographic) measurement techniques and their implementation into a novel diagnostic devices for nondestructive characterization of semiconducting crystals and structures. It was foreseen to develop the technique of dynamic holography, exploring nonresonant mechanisms of optical nonlinearities in a photoexcited semiconductor. The developed techniques and the prototypes of device were to be adapted for diagnostics of semiconductor materials, important for industry and market of semiconductor electronics and optoelectronics

Characterisation of bulk crystals and structures by light-induced transient grating technique

Electronic and optical properties of bulk crystals and epistructures have been studied via light interaction with inherent growth defects, deep impurities and defect complexes. Excitation by light interference pattern allowed us to monitor spatially-modulated carrier generation, recombination and transport in subnanosecond time domain, determine photogenerated carrier density, lifetime, diffusion coefficient and study defect-related features in an all-optical way

Non-destructive optical characterization of the surface region in bulk semiconductors and heterostructures

This paper describes application of picosecond non-degenerate four-wave mixing spectroscopy for the characterization of the surface region in layered semiconductor heterostructures. To demonstrate the influence of decreasing dimensionality of a structure on the experimental results, three model systems with progressively decreasing average layer thickness l(z): bulk GaAs (l(z) --> infinity), CdTe/ZnTe heterostructure (l(z) approximate to 1 um), and GaAs/InGaAs MQW structure (l(z) approximately 10 nm) were characterized by non-degenerate four-wave mixing. Analysis of the obtained data demonstrates important aspects related to application of this technique for the characterization of thin films and low-dimensional structures