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GaN with intentionally incorporated carbon to create semi-insulating buffer layers shows improved performance in AlGaN/GaN heterojunction field effect transistors. Moreover, various impurities and crystal imperfections of GaN epi-layers determine a rather rich spectrum of deep levels. Thus, spectroscopy of defects is of paramount importance in optimizing GaN-based devices. In this work, pulsed photo-ionization spectroscopy (PPIS) has been applied to trace the prevailing defects and simultaneously monitor variations of carrier lifetime in metal−organic chemical vapor deposition grown GaN epi-layers on Si substrates of various carbon content concentration. A contactless technique for microwave probed photoconductivity has been employed to measure changes in excess carrier density, in order to evaluate variations in carrier lifetime and reveal the type of photo-activation processes. Six PPI spectral steps have been resolved in samples containing either superlattices (SLs) or AlN/AlGaN stress management layers. Three of these centres, namely, and (CNON)0, have been associated with carbon dopants. Other PPIS peaks have been ascribed to Ga vacancies and metal impurities. It has been deduced from analysis of the PPIS peak broadening factor that rather strong electron−phonon coupling is inherent in photo-ionization of carbon related complexes at room temperature. The concentration of separated defects and cross-sections for photon−electron coupling have been determined using calibration measurements of optical transmittance spectra and correlations between microwave probed photoconductivity peak signals and absorption coefficient. [ABSTRACT FROM AUTHOR]

Copyright of Lithuanian Journal of Physics is the property of Lithuanian Academy of Sciences and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Lithuanian Journal of Physics is the property of Lithuanian Academy of Sciences and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

A set of n-type silicon samples has been irradiated by 6.6 MeV electrons with doses from 1 to 5 (x 1016) e/cm2, and temperature dependences of Hall and magnetoresistance mobilities were measured. The ratio of magnetoresistance and Hall mobilities was found equal to 1.15 ± 0.25. The correspondence of the data measured by both methods opened the possibility of measurement of electron mobility in semiconductors with microinhomogeneities by magnetoresistance effect investigation. [ABSTRACT FROM AUTHOR]

The particle detector degradation mainly appears through decrease of carrier recombination lifetime and manifestation of carrier trapping effects related to introduction of carrier capture and emission centers. In this work, the carrier trap spectroscopy in Si 1-x Ge x structures, containing either 1 or 5% of Ge, has been performed by combining the microwave probed photoconductivity, pulsed barrier capacitance transients and spectra of steady-state photo-ionization. These characteristics were examined in pristine, 5.5 MeV electron and 1.6 MeV proton irradiated Si and SiGe diodes with n + p structure.

Wide bandgap AlGaN is one of the most promising materials for the fabrication of radiation hard, double-response particle detectors for future collider facilities. However, the formation of defects during growth and fabrication of AlGaN-based devices is unavoidable. Furthermore, radiation defects are formed in detector structures during operation at extreme conditions. In this work, study of evolution of the proton-induced luminescence spectra and short-circuit current has been simultaneously performed during 1.6 MeV proton irradiation. GaN and AlGaN (with various Al concentrations) epi-layers grown by metalorganic chemical vapour deposition technique and Schottky diode structures have been examined. Variations of spectral and electrical parameters could be applied for the remote dosimetry of large hadron fluences., Competing Interests: The authors declare no conflict of interest.