The article presents the experimental results of research works aimed at manufacturing photoconductive semiconductor switches (PCSSs) on semi-insulating (SI) gallium phosphide (GaP) wafers. The PCSS is an electrical switch, triggered into the conduction state by means of an optical pulse with specific photon energy. The switches presented in the paper are developed for the applications in power systems and high-pulse voltage generators. The paper presents time courses of the photocurrent being a response to the excitation of semiconductor material with an optical pulse that generates excess charge carriers. The effect of laser beam photon energy on the height and time constant of photocurrent pulses was determined. The results of measurements of photocurrent in the conduction state for various values of electric field strength are presented. The research methodology was discussed and the measuring system used was described. Possible directions of further research were also presented. The research was carried out thanks to the cooperation of scientific teams from the Military University of Technology (WAT) and the Institute of Electronic Materials Technology (ITME).
The paper shows initial experimental results of research works taken by teams of the Institute of Electronic Materials Technology and Military University of Technology aimed at manufacturing in Poland photoconductive semiconductor switches (PCSSs) on semi-insulating (SI) gallium phosphide (GaP) wafers. These devices will allow pulsed switching of power circuits to high-voltage networks as well as triggering the high-energy of electromagnetic radiation. The properties and concentrations of deep-level defects, contributing to the charge compensation enabling the SI GaP crystals to be obtained, have been studied by the high-resolution photoinduced transient spectroscopy (HRPITS). The chips of switches with two planar electrodes separated by a gap of 2 mm were made and the connections enabling the dark current and photocurrent measurements as a function of the electric field strength to be carried out were assembled. The ways of increasing the switch amperage in the conductive state are discussed.
High resolution photo induced transient spectroscopy has been utilized to study defect centers in semi-insulating molecular beam epitaxy GaAs grown at temperatures 300 and 400 $DEGC. A number of traps with activation energies ranging from 0.004 to 0.64 eV have been detected. The traps are tentatively identified with native defects in GaAs lattice. The effect of the growth temperature on the defect structure of the layers is shown.
The technique of low frequency noise vs temperature is a powerful tool for study of deep level impurities in semiconductors materials. The physical parameters of the deep level defects are possible to identify from noise data. Measurement system to measure low noise spectra in frequency range from 0.01 kHz at temperature from 77K to 350K has been described.
Deep states in semi-insulating Si are investigated by analyzing of two-dimensional Photo-Induced Transient Spectroscopy (PITS) spectra. The results exemplify new potentialities of the advanced computer programming technique.
Defect structure of semi-insulating GaAs substrates manufactured by various vendors were compared using High Resolution Photo-Induced Transient Spectroscopy. A number of defect centers related to native defects and metallic impurities were detected and the concentrations of these centers were estimated.
Deep states in semi-insulating GaAs and InP are investigated by high resolution photo-induced transient spectroscopy (PITS). The results exemplify new potentialities of the improved PITS technique.
Digital PITS technique was applied to study deep-level defects in semi-insulating GaAs and InP. The studies were completed by measurements of ESR spectra on the same wafers.
Electrically active defects in preannealed n-type Cz-Si crystals subjected to high-pressure heat treatment were studied by deep level transient spectroscopy (DLTS). Experimental evidence is given that electron traps at Ec - 0.20 eV, Ec - 0.45 eV and Ec - 0.62 eV are presumably related to an oxygen-multivacancy complex, an acceptor level of Ni and a point defect decorating extended defects, respectively.
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