Selenophosphate Pb₂P₂Se₆ Single Crystals Growth by Chemical Vapor Transport (CVT) Method for Radiation Detection

The heavy metal selenophosphate Pb₂P₂Se₆ emerges as a promising room-temperature X-ray/γ-ray detectors due to its high resistivity, robust radiation-blocking capability, and outstanding carrier mobility-lifetime product, etc. However, the high activity of phosphides poses significant impediment to the synthesis and single crystal growth. In this work, we have prepared high-quality Pb₂P₂Se₆ single crystals with using the chemical vapor transport (CVT) method. The XRD analysis combined with EDS result confirmed the uniform composition of the resulting as-grown single crystals, while UV-Vis-NIR transmittance spectra revealed the bandgap of 1.89 eV. Selected area electron diffraction patterns indicated the crystal belonged to the P2₁/c(14) space group. Additionally, the Au/Pb₂P₂Se₆/Au device is fabricated, which exhibits a robust X-ray response with a sensitivity of 648.61 μC Gy⁻¹ cm⁻² at 400 V mm⁻¹ under 50 kVp. Notably, the device also excels in alpha particle detection, boasting a resolution of ~14.48 % under a bias of 400 V bias. The hole mobility-lifetime product (μτ)_h of Pb₂P₂Se₆ is estimated to be ~2.58×10⁻⁵ cm² V⁻¹. The results underscore potential applications of Pb₂P₂Se₆ crystal is in the field of the semiconductor radiation detectors.