Gaubas E.,Vilnius University |
Ceponis T.,Vilnius University |
Deveikis L.,Vilnius University |
Meskauskaite D.,Vilnius University |
And 8 more authors.
Journal of Physics D: Applied Physics | Year: 2017
Study of the radiation damage in GaN-based materials becomes an important aspect for possible application of the GaN detectors in the harsh radiation environment at the Large Hadron Collider and at other particle acceleration facilities. Intentionally doped and semi-insulating bulk ammonothermal GaN materials were studied to reveal the dominant defects introduced by reactor neutron irradiations. These radiation defects have been identified by combining electron spin resonance and transmission spectroscopy techniques. Characteristics of carrier lifetime dependence on neutron irradiation fluence were examined. Variations of the response of the capacitor-type sensors with neutron irradiation fluence have been correlated with the carrier lifetime changes. The measurements of the photoconductivity and photoluminescence transients have been used to study the variation of the parameters of radiative and non-radiative recombination. The examined characteristics indicate that AT GaN as a particle sensing material is radiation hard up to high hadron fluences 1016 cm-2. © 2017 IOP Publishing Ltd.
Krupka J.,Instytut Mikroelektroniki i Optoelektroniki Politechniki Warszawskiej |
Zajac M.,Ammono |
Kucharski R.,Ammono |
Gryglewski D.,Instytut Radioelektroniki i Technik Multimedialnych Politechniki Warszawskiej
AIP Advances | Year: 2016
Permittivity, the dielectric loss tangent and conductivity of semi-insulating Gallium Nitride crystals have been measured as functions of frequency from 10 GHz to 50 GHz and temperature from 295 to 560 K employing quasi TE0np mode dielectric resonator technique. Crystals were grown using ammonothermal method. Two kinds of doping were used to obtain high resistivity crystals; one with deep acceptors in form of transition metal ions, and the other with shallow Mg acceptors. The sample compensated with transition metal ions exhibited semi-insulating behavior in the whole temperature range. The sample doped with Mg acceptors remained semi-insulating up to 390 K. At temperatures exceeding 390 K the conductivity term in the total dielectric loss tangent of Mg compensated sample becomes dominant and it increases exponentially with activation energy of 1.14 eV. It has been proved that ammonothermal method with appropriate doping allows growth of high quality, temperature stable semi-insulating GaN crystals. © 2016 Author(s).