Effect of Na doping on structural, optical, and dielectric properties of SnSe polycrystals

摘要

Recently, tin selenide has attracted vast research interest in many fields due to its unique properties. Here, Na-doped SnSe polycrystals were successfully synthesized using hydrothermal method. Single phase was exhibited by all the samples as revealed from X-ray diffraction (XRD). Scanning electron microscope (SEM) studies for undoped SnSe showed a 2D plate-like morphology and converted it into 3D flower-like morphology with increasing Na concentration. The optical bandgap values obtained using UV-VIS-NIR diffuse reflectance spec-troscopy were found to decrease with increasing Na concentration. Dielectric and electrical modulus studies were carried out in the frequency range from 100 Hz to 10 MHz for temperatures from 323 to 523 K. Correlated barrier hopping (CBH) is a probable mechanism for the charge carriers in all the compositions of Na_xSn_(1-x)Se. The electrical modulus studies indicated an incomplete dielectric relaxation of the non-Debye type. The high values of the real part of permittivity and AC conductivity for the Na_(0.20)Sn_(0.80)Se sample have potential applications as capacitive energy-storage devices.