Investigation of high-temperature charge transport mechanism in Al-Gd_2O_3-Al-based metal-insulator-metal (MIM) structure

摘要

In this paper, the charge conduction mechanism at high temperature in Al-Gd_2O_3 (MIM) structure has been investigated by performing temperature-dependent current-voltage measurements in the temperature range 280-390 K. MIM structure is realized by electron beam evaporation system where thin films of Gd_2O_3 (40, 60 and 80 nm) and Al metal on both sides of dielectric film were deposited on glass substrate. The possibility of different transport mechanisms has been testified by plotting various graphs. The nonlinear behavior of LnV versus LnI and V~(1/2) versus LnV/I graphs ruled out the possibility of space-charge-limited conduction (SCLC) and Poole-Frenkel mechanism in Al-Gd_2O_3-Al MIM structure. The straight lines LnI-V~(1/2) graphs at various temperatures confirmed that Schottky emission is the dominant transport mechanism in Al-Gd_2O_3-Al structure. The calculated values of field barrier lowering coefficient at different measurement temperatures were in good agreement with the theoretical prediction confirming conduction is via Schottky emission. The field-dependent Ln(I/T~2) versus 1000/T plots were obeyed a linear relationship according to Schottky emission theory. Furthermore, the dielectric thickness dependence room-temperature current-voltage characteristics of Al-Gd_2O_3-Al MIM structure were showed strong dependence of current on dielectric film thickness according to Schottky emission theory of conduction current.