Highly efficient scintillation crystals with short decay times are indispensable for improving the performance of numerous detection and imaging instruments that use- X-rays, gamma-quanta, ionising particles or neutrons. Halide perovskites emerged recently as very promising materials for detection of ionising radiation that motivated further exploration of the materials. In this work, we report on excellent scintillation properties of CsPbBr3 crystals when cooled to cryogenic temperatures. The temperature dependence of luminescence spectra, decay kinetics and light yield under excitation with X-rays and α-particles was investigated. It is shown that the observed changes of spectral and kinetic characteristics of the crystal with temperature can be consistently explained by radiative decay of free excitons, bound and trapped excitons as well as electron-hole pairs originating from their disintegration. It has been found that the crystal exhibits a fast decay time constant of 1 ns at 7 K. The scintillation light yield of CsPbBr3 at 7 K is assessed to be 50,000 ± 10,000 ph/MeV at excitation with 12 keV X-rays and 109,000 ± 22,000 ph/MeV at excitation with α-particles of 241Am. This finding places CsPbBr3 in an excellent position for the development of a new generation of cryogenic, efficient scintillation detectors with nanosecond response time, marking a step-change in opportunities for scintillator-based applications.

CsPbCl3 crystal is found to be a promising material for the detection of ionising radiation at low temperatures.

Gallium oxide has recently been identified as a promising scintillator. To assess its potential as a detector material for ionizing radiation at low temperatures, we measured the luminescence and scintillation properties of an undoped Ga 2 O 3 crystal over the 7-295 K temperature range. The emission of the crystal is due to the radiative decay of self-trapped excitons and donor-acceptor pairs and peaks at a wavelength of 380 nm. The scintillation light output of the undoped Ga 2 O 3 increases with a decrease in temperature, reaching a maximum value of 19 300 6 2200 ph/MeV at 50 K. The measured luminescence kinetics has a recombination character with specific decay time (s 0.1 ) increasing from 1 to 1.8 ls at cooling. Since radiative decay in the crystal competes with nonradiative processes, material optimization could lead to the scintillator achieving a yield of 40800 ph/MeV, a figure considered to be an upper limit.

We have studied the surface morphology and intrinsic absorption spectra for zinc oxide thin fi lms with different levels of doping by indium, aluminum, or gallium, deposited by high-frequency magnetron sputtering on glass substrates. We show that as the dopant concentration increases (indium >5 wt.%, aluminum >0.3 wt.%, and gallium >2.2 wt.%) in ZnO fi lms, a decrease may occur in the average sizes of the crystallites and accordingly there may be an increase in the concentration of structural defects in the form of intercrystallite boundaries. We have established that in ZnO fi lms, with an increase in the indium dopant concentration from 1.7 to 6.6 wt.%, the optical bandgap width decreases from 3.30 to 3.27 eV due to the increase in the number of structural defects. We estimate the concentration of free charge carriers and show that the shift in the fundamental absorption edge in thin fi lms of ZnO:Al and ZnO:Ga as the dopant level increases is due to the Burstein-Moss effect.Introduction. The market for transparent conducting oxides, used in illumination devices, displays, and photovoltaics, will reach ≈$9.4 billion by 2015 according to estimates the NanoMarkets company [1]. Tin-doped indium oxide (ITO) to date has maintained its leading positions, despite its high price (≈$1000/kg). Currently, inexpensive and nontoxic semiconductor materials based on ZnO doped with In [2], Al [3], and Ga [4] are an alternative to ITO.An important engineering challenge is to use inexpensive starting materials to obtain high quality conducting fi lms based on zinc oxide with good structural, morphological, optical, and electrical characteristics. In this paper, we present the results of a study of the effect of surface morphology on the optical spectral and electrical properties of thin fi lms of zinc oxide with different levels of doping with indium, aluminum, or gallium, deposited on glass substrates.The Experiment. Thin fi lms of ZnO:In (1.7, 3.3, 5.0, and 6.6 wt.% In), ZnO:Al (0.3, 0.6, 1.4 wt.% Al), ZnO:Ga (1.5, 2.2, 3.7, 5.2, and 7.4 wt.% Ga) were obtained by high-frequency magnetron sputtering for a target made from a compressed mixture of ZnO and In 2 O 3 , ZnO and Al(NO 3 ) 3 , ZnO and Ga 2 O 3 powders (c.p. grade), used in appropriate proportions, for a glass substrate temperature of 300°C [5]. The sputtering time was 60 minutes. The fi lm thickness was determined by the ellipsometric method. The surface morphology of the experimental samples was studied using a Solver P47-PRO atomic force microscope (NT-MDT, Russia). The optical absorption spectra were measured at room temperature on a Specord M-40 spectrophotometer (Germany).Results and Discussion. As we know [6], for low concentrations of the dopant, the indium atoms replace the zinc atoms at crystal lattice sites, stimulating growth of the crystallites in the fi lm and accordingly the surface roughness. However, even at a concentration of In > 5 wt.%, we observe a decrease in the crystallite sizes from 82 nm to 76 nm. This effect may be a consequence of the fact...

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