Nonequilibrium transport and Electron-Glass effects in thin GexTe films

Abstract

We report on results of nonequilibrium transport measurements made on thin films of germanium-telluride (Ge_xTe) at cryogenic temperatures. Owing to a rather large deviation from stoichiometry (app. 10% of Ge vacancies), these films exhibit p-type conductivity with carrier-concentration N>10^20cm^(-3) and can be made either in the diffusive or strongly-localized regime by a judicious choice of preparation and post-treatment conditions. In both regimes the system shows persistent photoconductivity following excitation by a brief exposure to infrared radiation. Persistent photoconductivity is also observed in GexTe samples alloyed with Mn. However, in both Ge_xTe and GeMn_xTe_y the effect is much weaker than that observable in GeSb_xTe_y alloys suggesting that antimony plays an important role in the phenomenon. Structural studies of these films reveal an unusual degree of texture that is rarely realized in strongly-disordered systems with high carrier-concentrations. Anderson-localized samples of Ge_xTe exhibit non-ergodic transport which are characteristic of intrinsic electron-glasses, including a well developed memory-dip and slow relaxation of the excess conductance created in the excited state. These results support the conjecture that electron-glass effects with inherently long relaxation times is a generic property of all Anderson-localized systems with large carrier-concentration.

References in corpus (19)

• The glass transition and the Coulomb gap in electron glasses
• Time Dependent Development of the Coulomb Gap
• Electron Glass Dynamics
• Stress-aging in the electron-glass
• A mean-field model for the electron glass dynamics
• Symmetrical field effect and slow electron relaxation in granular aluminium
• The Memory Effect in Electron Glasses
• Off-equilibrium dynamics of the two-dimensional Coulomb glass
• Suppression of inelastic electron-electron scattering in Anderson Insulators
• Temperature and field dependence of Dynamics in the Electron-Glass
• Slow conductance relaxations; Distinguishing the Electron Glass from extrinsic mechanisms
• History dependence, memory and metastability in electron glasses
• Ulta-slow relaxation in discontinuous-film based electron glasses
• Electron Glass in a three-dimensional system
• Memory Effects in the Electron Glass
• Intrinsic electron-glass effects in strongly-localized thallium-oxide films
• Coexistence of Electron-Glass Phase and Persistent Photoconductivity in GeSbTe Compounds
• Band-tail shape and transport near the metal-insulator transition in Si-doped Al(0.3)Ga(0.7)As
• Infrared-Induced Sluggish Dynamics in the GeSbTe Electron Glass

Cited by in corpus (5)

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• Electron glass effects in amorphous NbSi films
• Electron glass signatures up to room temperature in disordered insulators
• Anomalous thermal activation of the electron glass dynamics in a-InOx and granular aluminum