Growth of a CuSbSe₂ single crystal by the Bridgman technique and its utility as a photodetector and thermoelectric material

Looking at the literature survey, this seems to be the first report on growth of a copper antimony diselenide (CuSbSe2) single crystal with a 5.8 cm length and 1.0 cm diameter by the vertical Bridgman technique. The validation of the orthorhombic crystal structure of CuSbSe2 is obtained through outcomes of the powder X-ray diffraction pattern. The stoichiometry of the grown crystal is corroborated via energy dispersive X-ray analysis, whereas field emission scanning electron microscopy displays a growth pattern comprising both a smooth surface and layer growth. The confirmation of the crystalline nature of the crystal is provided by the distinctive spot patterns observed in the selected area electron diffraction pattern. The observed d value closely corresponds to the d value of the prominent (112) plane of orthorhombic CuSbSe2. The Raman spectra depicted two prominent peaks at 194.74 cm-1 and 232.32 cm-1 corresponding to the Ag vibrational mode and also showed the orthorhombic phase of CuSbSe2. Optical reflectance spectroscopy substantiated that the CuSbSe2 single crystal possesses a direct bandgap of 1.3 eV, rendering it a suitable candidate for potential solar cell applications. Throughout the temperature range from 310 K to 586 K, the Seebeck coefficient maintains a positive value, conclusively affirming the p-type semiconducting nature of the sample. Remarkably, zT (figure of merit) attains a value of approximately 0.976 at 543 K, a result that competes effectively with values reported for other grown crystals. The thermogravimetric (TG) curve indicated weight gain along with weight loss, which is also confirmed by the differential thermogravimetric analysis (DTG) curve at different heating rates of 5, 10, 15 and 20 K min-1. Furthermore, the I-V characteristics of the CuSbSe2 single crystal photodetector are recorded at room temperature at varying bias voltages and a light intensity of 50 mW cm-2. Pulse photoresponse is recorded for the parallel to planar configuration, and from I-V characteristics some important parameters such as photocurrent, sensitivity, responsivity, detectivity, rise time and decay time are determined. At room temperature, employing a bias voltage of 500 mV along with a light intensity of 50 mW cm-2 led to responsivity and detectivity values of 52.664 mA W-1 and 2.317 x 109 Jones for the parallel to planar configuration.