Tailoring Dielectric Relaxation and Charge Transport in Amorphous Ge-Te-Se Phase-Change Materials through Yttrium Incorporation
The Te(1-x)(GeSe0.5)Yx (x = 0.05, 0.10, 0.15) alloys were prepared by a melt-quenching method and characterized using dielectric spectroscopy. The dielectric parameters and electrical conductivity were evaluated to assess their potential for phase-change memory and other electronic applications. The temperature and frequency dependence of the dielectric constants, ac conductivity, and dielectric loss of prepared chalcogenide glassy alloys were investigated over the frequency range 1 Hz - 1 MHz, and the temperature range 302 - 422 K, below the glass transition temperature. Both dielectric loss and dielectric constant were found to decrease with increasing frequency and decreasing temperature. The observed dielectric loss change was interpreted using the Guintini model of dielectric dispersion, correlated barrier hopping (CBH) model, and orientation polarization. The Cole-Cole analysis confirmed a distribution of relaxation times and yielded activation energies consistent with the CBH conduction mechanism. The frequency dependence of the ac conductivity follows the power law (Aωs), where the frequency exponent (s < 1) decreases with increasing temperature, further supporting the CBH conduction mechanism. The incorporation of Y increases the density of localized tail states, resulting in enhanced ac conductivity. These findings suggest that the investigated materials are promising candidates for future phase-change memory and other electronic device applications.