Impact of metal electrode on charge transport behavior of metal-Gd2O3 systems

• Charge transport mechanism in metal-Gd2O3-metal systems in the temperature range 290–380 K.
• Al, Cu, Cr and Au metal electrodes were fabricated on 80 nm Gd2O3 thin film by E.B evaporation.
• Mott VRH is responsible for conduction behavior in all systems for entire temperature range.
• A strong correlation between transport properties and metal work function has been observed.
• σ decreased from 2.9 × 10−5 to 1.8 × 10−11 S/cm as the metal φ increased from 4 to 5.1 eV for Al to Au.

In this paper, we have grown an 80 nm thick Gd2O3 thin film by electron beam evaporation on glass substrate and fabricated different metal (Al, Cu, Cr and Au) electrodes on grown sample under same condition. To investigate the charge transport mechanism in these metal-semiconductor systems, the electrical conductivities and current–voltage (I–V) measurements have been measured over temperature range of 250–400 K. We have found that Mott variable range hopping (VRH) is responsible for conduction behavior in all systems for entire temperature range. A strong correlation between transport properties and metal work function has been observed. A space charge model successfully explained the decreasing trend of conductivity with increasing the metal work function. The conductivity decreased from 2.9 × 10−5 to 1.8 × 10−11 S/cm as the metal work function increased from 4 to 5.1 eV for Al to Au metals respectively. The ideality factor also increased from 1.67 to 2.2 with metal work function from Al to Au metal. The observed result can be explained as; high work function metal forms higher depletion layer as compared to metal having low work function, which compensate the empty sites available for hopping and consequently decreased the hopping conductivity.

Different metal electrodes (Al, Cu, Cr and Au) were fabricated on 80 nm Gd2O3 thin film by electron beam evaporation and found that Mott VRH is responsible for conduction behavior in all systems for entire temperature range. We also observed a strong correlation between transport properties and metal work function has been observed.Figure optionsDownload as PowerPoint slide