Abstract
We report a performance comparison of Zr, Bi, Ti, and Ga as metal contacts on solution-grown CsPbBr <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sub> single-crystal gamma-ray detectors. The same CsPbBr <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sub> single crystal was repeatedly deposited with different metal contacts for the evaluation of gamma spectral performance to eliminate crystal-to-crystal variation. Leakage current as low as 2-3 nA at -200 V with detector thickness 2-3 mm was consistently achieved with Zr, Bi, Ti, and Ga as Schottky contact metal, which is comparable to the leakage current level of a commercial cadmium zinc telluride (CZT) detector. Gamma energy spectra with a prominent photopeak at 662 keV were consistently acquired with all studied metal contacts. The best resolution at 662 keV is 11% with a peak-to-Compton valley ratio of 2, indicating an improved spectrum shape than previous results. Through Americium-241 ( <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">241</sup> Am) alpha spectra acquisition, the hole mobility of the CsPbBr <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sub> single crystal is evaluated to be 1.78 cm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> V <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">-1</sup> s <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">-1</sup> . We also discussed issues related with the CsPbBr <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sub> gamma detector architecture and interface layers, commonly encountered during CsPbBr <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sub> gamma detector fabrication, that is, impact of electron/hole transport layer and surface oxide layer on gamma detector spectral performance, comparison of different metal-perovskite-metal structures. The persistent CsPbBr <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sub> gamma spectral performance marks the good reproducibility of CsPbBr <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sub> gamma detectors, further enabling CsPbBr <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sub> detector field applications.
Highlights
R OOM-TEMPERATURE semiconductor gamma-ray detectors with good energy resolution have wide applications in nuclear defense, homeland security, medical imaging, and academic research [1]–[3]
The lead (Pb) halide perovskites emerged as a promising alternative to the cadmium zinc telluride (CZT) detector owing to their favorable properties for room-temperature X- and gamma-ray detection
We compared the performance of Zr, Bi, Ti, and Ga as metal contacts in a gamma-ray detector made of inorganic perovskite CsPbBr3
Summary
R OOM-TEMPERATURE semiconductor gamma-ray detectors with good energy resolution have wide applications in nuclear defense, homeland security, medical imaging, and academic research [1]–[3]. Their high effective atomic number (Zeff ) offers a high gamma-ray attenuation coefficient. Gamma spectral resolution of 3.8% resolution at 662 keV has been reported from the CsPbBr3 detector made of melting-grown single crystals [12]. This work focuses on their consistent spectroscopy performance with an improved gamma spectral feature (i.e., peak-to-Compton valley at 2) when applying different metal contacts. We report CsPbBr3 gamma-ray detector spectral performance reproduced with various Schottky contact metals, that is, zirconium (Zr), bismuth (Bi), titanium (Ti), and gallium (Ga). Quality variation, only one solution-grown CsPbBr3 single crystal (labeled as crystal #1) was deposited repeatedly by all studied metal electrodes for gamma spectral performance comparison. The fact that the same CsPbBr3 single crystal can be used repeatedly with consistent gamma spectral performance indicates the robustness and good quality of reutilization of CsPbBr3 single crystals
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