Ultrafast growth of high-quality large-sized GaSe crystals by liquid metal promoter

Growth of high-quality large-sized crystals using the traditional chemical vapor transport (CVT) or vertical Bridgman (VB) technique is costly and time-consuming, limiting its practical industrial application. Here, we propose an ultrafast crystal growth process with low energy consumption and capability of producing crystals of excellent quality, and demonstrate that large-sized GaSe crystals with a lateral size of 0.5 to 1 cm can be obtained within a short period of 5 min. X-ray diffraction (XRD) and scanning transmission electron microscopy (STEM) studies clearly indicate that the as-grown crystals have a good crystallinity. To further show the potential application of the resulting GaSe crystals, we fabricate the few-layer GaSe-based photodetector, which exhibits low dark current of 21 pA and fast response of 34 ms under 405 nm illumination. Our proposed technique for rapid crystal growth could be further extended to other metallenes with low-melting point, such as Bi-, Sn-, In-, Pb-based crystals, opening up a new avenue in fulfilling diverse potential optoelectronics applications of two-dimensional (2D) crystals.