Study of electrical properties of L-Cysteine-doped potassium dihydrogen phosphate crystals grown under the influence of electric field

Potassium dihydrogen phosphate (KDP) is a well-known non-linear optical material and has numerous applications related to electro-optic switching and laser systems. L-cysteine (C₃H₇NO₂S)-doped KDP crystals were grown using the slow evaporation solution growth method. The conventional two-probe method was used to perform impedance spectroscopy in order to study the dielectric behaviour and conduction mechanism between 323 and 373 K at frequencies between 100 Hz and 1 MHz. According to this study, the conductivity of KDP crystals increases with temperature and impurity concentration in the presence of electric field. The dielectric loss, dielectric constant, complex impedance modulus, alternating current (ac) and direct current (dc) conductivities of pure and L-cysteine-doped KDP crystals have been measured as functions of frequency, temperature and doping concentration. It is observed that the conductivity of crystals changes with temperature, indicating that this change is thermally induced. Jonscher’s universal power law has been used to analyse frequency dependence of ac conductivity. As the temperature increases, the value of s decreases, which implies that the ac conduction mechanism of crystals follows correlated barrier hopping (CBH) mechanism.