Refined Synthesis and Single Crystal Growth of PbGa2Se4 by Chemical Vapor Transport Method for Photodetection

Abstract Ternary chalcogenide PbGa 2 Se 4 with high resistivity, photosensitivity, and excellent nonlinear properties, exhibits a potential application in optoelectronic and nonlinear optical devices. However, the preparation of large‐sized pure PbGa 2 Se 4 crystals is challenging due to the presence of peritectic reaction and a narrow homogeneity region. Here, a “quenching‐annealing” method (quenching at 850 °C in ice water, and then annealing at 650 °C for 250 h by reheating) is developed to eliminate the PbSe second phase during the synthesis. Subsequently, the PbGa 2 Se 4 single crystals are successfully grown using chemical vapor transport (CVT) with the I 2 as the transport agent. The resulting crystal exhibits the crystal structure belonging to Fddd space group with the lattice parameters of a = 12.7192 Å, b = 21.2831 Å, and c = 21.5226 Å. Additionally, it possesses a wide bandgap (≈2.26 eV), high resistivity (6.59 × 10 12 Ω·cm), and defect density calculated via space charge limited current measurement (SCLC) as 2.46 × 10 11 cm −3 . Photodetectors based on these as‐grown crystals demonstrate exceptional photosensitivity along with a high detectivity (3.2 × 10 8 Jones).