Investigation on radiation damages in GaN-based materials is an important factor in possible application of GaN as particle detectors in harsh radiation environment in any particle acceleration facilities like Large Hadron Collider, built by the European Organization for Nuclear Research (CERN) near Geneve, Switzerland. AMMONO SA in cooperation with the group of prof. Jouzas Vaitkus from Vilnius University is engaged in deep research of ammonothermal GaN substrates, aiming at such applications. The results were published in paper by E. Gaubas et al, Journal of Physics D: Applied Physics 50 135102 (2017).
Researchers from Vilnius University performed extensive studies on defects formed in AMMONO-GaN wafers after neutron irradiation at TRIGA nuclear reactor (Slovenia). Several types of AMMONO semi-insulating (SI) GaN samples have been investigated before and after wide range of neutron fluences 1×1012 – 5×1016 cm-2 by variety of experimental techniques.
The measurements revealed exceptionally long carrier lifetimes, up to several µs, which makes AMMONO-GaN SI-type wafers applicable in formation of thick sensors for detection of particles with small interaction cross section. High carrier lifetime determines high value of a charge collection efficiency (CCE) and possibility to detect electrical signals on the background of electrical noise. Moreover, the nearly unchanged values of CCE and carrier lifetime over wide range of moderate neutron fluences Φ≤ 1015 cm-2 confirmed the high radiation hardness of the material. At the highest neutron fluence (5×1016 cm-2) the CCE signal can be registered by at least pulsed laser carrier injection, while photoluminescence signals are still at the detectable level.
The research outcome showed that AMMONO-GaN semi-insulating wafers definitely are suitable as a particle sensing material for high hadron fluences (≥1016 cm-2).
In nearest future fabrication of the first prototype of a particle detector with the use of AMMONO-GaN semi insulating type substrates is planned.