Bulk β-Ga2O3 single crystals doped with Ce, Ce plus Si, Ce plus Al, and Ce plus Al plus Si for detection of nuclear radiation

beta-Ga2O3 is an emerging ultra-wide bandgap (4.9 eV) oxide semiconductor that additionally scintillates under gamma excitation. A unique combination of transparency in the UV/visible spectrum, semiconducting, and scintillation properties makes that compound interesting for fundamental studies of underlying physics and design of novel devices, in particular compact detectors for gamma radiation. Undoped, and singly (Ce, Si, Al), doubly (Ce + Si, Ce + Al), and triply (Ce + Al + Si) doped bulk beta-Ga2O3 single crystals were grown by the Czochralski method under very similar conditions and systematically studied in terms of electrical and optical properties that were correlated with scintillation light yield under gamma excitation. A wide spectrum of doping enabled to control the free electron concentration in semiconducting beta-Ga2O3 crystals within almost three orders of magnitude (7 - 10(15)-6 - 10(18) cm(-3)) with the Hall mobility approaching 150 cm(2) V(-1)s(-1). The maximum of light yield under gamma excitation was recorded for undoped and Ce-doped beta-Ga2O3 single crystals having the free electron concentration of mid 10(16) cm(-3). The light yield significantly decreases for both electrically insulating and highly conducting (Si-doped) crystals. None of the dopants (Ce, Si, Al) introduces any absorption bands in the spectral region of light emission (340-410 nm) under gamma excitation. The dopants in quest do not affect the structure of neither cathodoluminescence (CL) nor radioluminescence (RL) emissions, but modify their absolute intensity. A double-band structure of RL spectra corresponds to UV and blue emissions observed in CL spectra that are assigned to self-trapped excitons. (C) 2019 Elsevier B.V. All rights reserved.