The growth of void-free ZnTe-based crystals from Te solution by re-dissolution procedure

Void defects are prevalent in ZnTe-based crystals and detrimentally impact their properties. This research aims to elucidate the composition and formation mechanism of the voids. In this experiment, ZnTe crystals were grown by the Te solution method. Energy dispersive spectroscopy (EDS) results demonstrate that the C, Te and Zn elements are distributed on the void surfaces. X-ray photoelectron spectroscopy (XPS) results indicate that the C element mainly exists as zero valence. These results suggest that the carbon film coated on the surface of the quartz crucible must be implicated in the bubble formation. Carbon film possibly reacts with the Te solution to produce a kind of CTe_n gas, which then dissolves into the Te solution. When the temperature decreases, the solubility of the gases diminishes, leading to the bubbles nucleate at the solid–liquid interface or within the Te solution, and further grow. When a bubble is wrapped by the solid–liquid interface, it evolves into a void in the crystal. To eliminate void in ZnTe-based crystals, the low–high temperature cycle procedure was developed to re-dissolve the crystals near the interface and released void, during the crystal growth. Fourier transform infrared spectrometer (FTIR) spectrum demonstrates that the optical properties of the ZnTe-based crystals grown by the re-dissolution procedure are improved significantly.