Growth and Characterization of Large-Size Inse Single Crystal from Non-Stoichiometric Solution Via a Zone Melting Method

Indium selenide (InSe) is a III-VI group semiconductor that shows interesting physical properties and has wide potential applications in the fields of diodes, photovoltaics, optics, and thermoelectrics. In view of the values in both academic research and commercial application, the growth of large-size, high-quality InSe single crystals has attracted great attention, but remains to be a challenge. In this work, a large-size InSe crystal ( Φ 27× 130 mm 3 ) has been successfully produced via a zone melting method from the non-stoichiometric composition of In 0.52 Se 0.48 , which is superior to all currently reported crystals. The as-grown InSe crystal shows a typical layered structure with homogenous elemental distributions. Chemical etching method reveals the crystal has an average etching pits density (EPD) of 2.10× 10 3 /cm 2 . The highest transmittance of a 0.8 mm thickness (001) InSe wafer is ~55% under 1800 nm wavelength and its band gap is about 1.22 eV. The InSe single crystal has a highest electrical conductivity σ around 1.55× 10 2 Sm -1 along (001) and a lowest thermal conductivity κ= 0.48 Wm -1 K -1 perpendicular to (001) at 800 K. Such high-quality InSe single crystal with currently largest size can be used for future study and applications in various fields.