Optical, Electrical and Surface Characterization of Mercuric Iodide Platelets Grown in the HgI 2-HI-H2O System

The optical, electrical and surface properties of mercuric iodide platelets grown from solution in a HgI2-HI-H2O system were investigated by comparing them with Physical Vapor Transport (PVT) grown crystals. The absence of bulk imperfections and the uniformity of the as-grown surfaces and the KI solution etched surfaces were confirmed by optical microscopy. The as-grown surface uniformity is higher for solution grown crystals than that of PVT crystals, since the platelets do not have to be cleaved or polished. AFM studies show that the roughness for the cleaved, aged and etched surfaces were 0.06 nm, 0.48 nm and 0.3 nm respectively. Low temperature photoluminescence properties were measured for the two kind of crystals and will be discussed. However, I-V curves give higher current density and lower apparent resistivity values for the solution grown than for PVT grown crystals. Correlations between optical and surface quality as well as the electrical properties of the crystals grown from both solution and PVT methods are also discussed.