Organic-inorganic perovskites have shown to be promising materials with great potential for use in radiation detection, in which higher energy photons or heavy charged alpha particles need to be detected. Halide-based rudorffites and double perovskites are suitable candidates for X- and γ- radiation detectors due to their relatively high atomic number and thus high stopping power, superior carrier life-time product, tunable band gap, and low temperature fabrication process. In this study, high-resistivity MAPbBr3 single crystals are investigated. Current–voltage characteristics of the ITO/PTAA/MAPbBr3/C60/BCP/Cu detectors were analyzed. The main parameters of the crystals and barrier structures were determined. The charge transport mechanisms in the structures under investigation within the entire voltage are well described in terms of the well-known theoretical models. The obtained electrical performance parameters indicate that the MAPbBr3 single crystals satisfy requirements for radiation detection application. The optimization of technological conditions of the formation of contacts to the MAPbBr3 crystals is necessary to decrease the leakage current through the barrier structures, and thus to improve the energy resolution of the detectors.
A ( I 1 10 1 10 7 8 Detector No2 Et = 0.5550.01 eV Nt = 1.7109 cm-3 = 5.24 cm2V-1s-1 ) 1 m c ( t n e i c i f f e o c n o i t a u n e t t A 100 10 1 y h p a r g o m m a m V e k 5 . 9 5 t s e h c total photoelectric 2.0 mm 0.5 mm CdTe V e k 2 6 6 0.01 0.1 1 P e n e t r a t i o n d e p t h ( c m ) Room-temperature current-voltage characteristics of the ITO/PTAA/MAPbBr3/C60/BCP/Cu detectors No1 and No2 in double-logarithmic coordinates. Approximations of the root (I ~ V 1/2), linear (I ~ V 1), and square-law (I ~V 2) I(V) dependences are shown by solid lines. The inset shows the voltage dependence of differential resistance Rdiff. Table I. Performance summary of MAPbBr-based -ray detectors 1 10 9 1 10 10 1 10 V (V) Detector No1 Et = 0.530.01 eV Nt = 7.63109 cm-3 = 0.9 cm2V-1s-1 100 Comparison of the reverse IV characteristics of the detectors: measured (circles) and calculated (solid lines). 0.1 1 10 4 5 1 10 Energy (eV)
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MAPbBr3 10 6 1 10 No 1 Resistivity , Ohmcm 4.2109 Hole concentration, p0, cm-3 1.62109 Traps ionization energy, Et, eV 0.5300.01 Trap-filledlimit voltage, Vtfl, V 27 Voltage for completely depleted crystal, VSCR 10.8 Trap density, Nt, cm-3 1.7109 Hole mobility, p, cm2V-1s-1 0.92 Energy resolution, % (Voltage) 137Cs (662 keV) 241Am (59.5 keV) 59.5 (-50 V) 116.35 (-80 V) SPECTROSCOPIC PROPERTIES 2 5.7109 2.09108 0.5550.01 6 1.7 7.63109 5.24 75.7 (-1 V) 112.65 (-10 V) s t n u o C 6 10 4 10 2 10 4 4 4 137 Cs (662 keV) Detector No1 V = -100 V FWHM = 59.5% Detector No2 V = -1 V FWHM = 75.7% CdTe Detector V = -100 V FWHM = 4.5% 30 20 10 C o u n t s (c) Cu BCP C60 MAPbBr3 PTAA ITO Glass hv Hole signal mainly V + ) . u . a ( , y c n e i c i f f E 1 0.1 0.01 1 10 3 1 10 4 0.01 59.5 keV 662 keV total photoelectric 0.1
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Thickness (mm) 4 8 10 1 10 Attenuation efficiency for photoelectric absorption and total absorption, including Compton scattering of MAPbBr3 to 59.5 keV and 662 keV -ray photons irradiated by 241Am and 137Cs isotopes as function of detector thickness. s t n u o C 4 5 10 4 2.5 10 CONCLUSION 241 Am (59.5 keV) 137 Cs (662 keV) V = -100 V hole and electron averaged signal V = -60 V V = -20 V (a) s t n u o C 6 10 4 10 0 4 4 0 200 400 600 800 Energy (keV) (b) 1000 1200 0 1400 600 Detector No1 V = -80 V FWHM = 116.4% Detector No2 V = -10 V FWHM = 112.7% 400 CdTe Detector V = -200 V FWHM = 34.8% C o u n t s (d) hv Electron signal mainly Cu BCP C60 MAPbBr3 V + PTAA ITO Glass s t n u o C 4 6 10 4 4 10 4 2 10 0 V = -80 V hole and electron averaged signal hole signal mainly V = -2 V electron signal mainly 50 100 Energy (keV) 150 (b) 0 0 200 400
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600 800 Energy (keV) 1000 1200 Energy spectra collected by ITO/PTAA/MAPbBr3/C60/BCP/Cu detector No1 under reverse bias (ITO contact biased positively), while the incident 241Am (59.5 keV) (a) and 137Cs (662 keV) (b) -ray source was from the ITO (hole signal only, diamonds) and Cu (electron signal only, solid lines) contact. Setup for acquisition of spectrum induced mainly by hole (c) or electron (d) transport signal 1400 2 10 4 200 CONCLUSIONS Currentvoltage characteristics of the ITO/PTAA/MAPbBr3/C60/BCP/Cu detectors were analyzed. The main parameters of the 0 241 0 Am (59.5 keV) 50 100 150 (a) 0 200 crystals and barrier structures were determined. The charge transport mechanisms in the structures under investigation within the entire voltage are well described in terms of the well-known theoretical models.
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