Scintillating structures of GaN on sapphire for hadron irradiation dosimetry

Abstract

Crystals of GaN and layered structures of GaN deposited on sapphire and on other substrates are promising in fabricating radiation hard dosimeters capable of functioning in the rather wide range (10¹¹- 10¹⁵ particle/cm²) of fluences. These structures are suitable for recording double response (electrical and optical) signals. The dynamic range of fluence estimation of the irradiation source potential in the creation of various radiation defects related to accumulated doses depends on the stopping range of definite detector materials. It is limited by the increased density of radiation defects in GaN and sapphire layers as a function of fluence. While penetrative particle irradiations are capable of exciting electronic transitions in sapphire substrates via radiation induced coloured F^±-centres composed of electron captured at an anion vacancy. Such a layered GaN/sapphire structure enables enhancement of the range of dosimetry fluence when scintillation and electrical responses are simultaneously collected from both GaN and Al₂O₃ materials. Moreover, GaN on Al₂O₃ fluence meters are solar-blind and insusceptible to IR noise. The simultaneous analysis of fluence dependent scintillation and microwave-probed photoconductivity characteristics have been examined in this study to highlight the beneficial mechanisms of radiative and non-radiative processes in order to produce the wide-range and radiation hard dosimeters. The possibilities and regimes of contactless recording of the electrical and scintillation signals by combining the microwave and optical probes have been demonstrated. Such a double–response fluence dosimetry can be implemented using both the in situ irradiation and post irradiation measurement regimes.