GaAs peculiarities related with inhomogeneities and the methods for revealof their properties

The inhomogeneities in as-grown and irradiated GaAs crystals and structures , their properties and role have been analysed. The influence of inhomogene ities on the properties of crystal and Schottky diode structure are present ed. The possibilities of different methods for material and structure chara cterisation (Hall effect and magnetoresistance, noise spectra, thermally st imulated current and polarisation, photoconductivity kinetics and spectrum, ;light-induced diffraction) are discussed. Existence of the inhomogeneity of the crystal structure has been revealed b y diffusion of copper through be GaAs wafer, and a percolation of it throug h doped crystal has been determined by means of the Hall effect. Modification of the recombination-induced defect system has been analysed t o get deeper insight into the crystal and device degradation under illumina tion by ionising radiation. Role of free carriers in local electric field g eneration has been analysed via modification of the EL2 centre in GaAs. Com plicated behaviour of no n-equilibrium conductivity during quenching and ac tivation of EL2 centres has been determined by precise measurement of the p hotoconductivity spectra in different crystals. Influence of the EL2 centre on the nob-linear polarisation of sample and on the additional non-active light absorption has been analysed. (C) 2001 Elsevier Science B,V. All righ ts reserved.