Kinetic modulation-eliminated precursor liquid inclusions in solution-grown CsPbBr₃ bulk crystals for gamma-ray detection

The understanding and suppression of grown-in defects are expected to promote the semiconductor radiation detector performance. Here, we report the origin of liquid inclusion defects in CsPbBr₃ crystals grown using the inverse temperature crystallization (ITC) method. The formation process of liquid inclusions is observed in situ and simultaneously the formation mechanism for liquid inclusions in CsPbBr₃ bulk crystals is proposed. Based on the COMSOL Multiphysics simulation, a model is developed combining concentration and temperature gradients, associated with natural convection during crystallization, and is responsible for the liquid inclusions. By introducing forced convection to eliminate liquid inclusions, the crystalline quality of CsPbBr₃ has been significantly improved, with the half-peak width of X-ray rocking curves optimized from 0.101° to 0.037°. A near one order of magnitude increase in bulk resistivity has been obtained while the hole mobility was improved to 142.95 cm⁻² V⁻¹ s⁻¹, evaluated by the time-of-flight technique according to α particle induced pulses. Furthermore, the CsPbBr₃ crystals free from liquid inclusions enable the fabrication of an asymmetric planar Au/CsPbBr₃/Sn device with an energy resolution of 7.2% illuminated with ¹³⁷Cs@662 keV γ-rays.