Optically Induced Space-Charge Gratings in Wide-Bandgap Semiconductors

by Igor A. Sokolov (Author), Mikhail A. Bryushinin (Author)

The photorefractive effect is one of the highest-sensitivity non-linear optical effects. The rate of progress in the development of photorefractive applications has been limited by the rate in which breakthroughs in materials science have supplied better wide-bandgap semiconductor materials. The last few years have seen an upsurge of interest in characterization of new wide-bandgap semiconductor materials. Holographic recording in wide-bandgap photorefractive materials is of particular interest from the scientific and practical point of view. Such a recording includes the stage of space charge formation, which is associated with the spatial redistribution of photoinduced carriers. A number of new methods studying the dynamics of space charge and photoconductivity in wide-bandgap semiconductors were proposed during recent years. This book deals with the so-called non-steady-state photo-EMF effect and its applications for material characterization and adaptive interferometry. The first part of the book discusses the theory of the non-steady-state photo-EMF effect. The second part describes the application of the non-steady-state photo-EMF effect for the investigation of wide- bandgap semiconductors and nanostructured materials, including photorefractive sillenites grown in the air and argon atmosphere, molecular crystal SnS2, boron nitride crystals, nano-sized GaN and Se within porous matrices, SiC, AlN and Ga2O3 crystals. The third part presents a theoretical analysis and experimental investigation of the non-steady-state photoelectromotive force and two-wave mixing in photorefractive crystals under frequency-modulated illumination. The final part describes adaptive interferometers using the effect of the non-steady-state photo-EMF. This book has been written to be accessible to specialists working in solid state physics, semiconductor physics and adaptive inter-ferometry, laser-based ultrasound.