Electrical properties and transport mechanisms in phase change memory thin films of quasi-binary-line GeTe–Sb$_{2}$Te$_{3}$ chalcogenide semiconductors

The temperature dependences of the resistivity and current–voltage (I–V) characteristics of phase change memory thin films based on quasi-binary-line GeTe–Sb$_{2}$Te$_{3}$ chalcogenide semiconductors GeTe–Sb$_{2}$Te$_{3}$: Ge$_{2}$Sb$_{2}$Te$_{5}$, GeSb$_{2}$Te$_{4}$, and GeSb$_{4}$Te$_{7}$ are investigated. The effect of composition variation along the quasibinary line on the electrical properties and transport mechanisms of the thin films is studied. The existence of three ranges with different I–V characteristics is established. The position and concentration of energy levels controlling carrier transport are estimated. The results obtained show that the electrical properties of the thin films can significantly change during a shift along the quasi-binary line GeTe–Sb$_{2}$Te$_{3}$, which is important for targeted optimization of the phase change memory technology.