Conductivity of Se$_{95}$As$_5$ chalcogenide glassy semiconductor layers containing the EuF$_3$ rare-earth impurity in high electric fields

By investigating the I–V characteristics of an Al-Se$_{95}$As$_5$ $\langle$EuF$_3\rangle$-Te structure, it is established that, upon the application of a positive potential to Te, the current flows in it by the mechanism of space-charge-limited currents (SCLCs) of unipolar-injection, and the $N$-type I–V characteristic is observed for the opposite polarity. It is shown that these are processes of the thermal-field ionization of neutral and negatively charged $U^-$ centers, which play a dominant role in the current-flow mechanism in the investigated structures upon the application of an electric field with intensities exceeding 10$^5$ V/cm. These are also processes of the electron-hole recombination and capture of charge carriers at $U^-$ centers. The energy position and concentration of the local states, which correspond to the indicated centers and characterize the effect of the electric field–activation length are determined. It is established that it is the EuF$_3$ impurities that predominantly affect the local-state concentration.