Space-Charge-Limited Currents in La₂O₃ Thin Films Deposited by E-Beam Evaporation after Low Temperature Dry-Nitrogen Annealing

Abstract

The electrical characteristics of metal–oxide–semiconductor capacitors with Lanthanum oxide (La2O3) gate dielectrics with 1.1 nm equivalent oxide thickness (EOT) are investigated. La2O3 was deposited by E-beam evaporation on n-Si(100), and annealed at 200°C in dry-nitrogen ex-situ for 5 min. From comparing the leakage currents of as-deposited and annealed oxides, it is shown that the leakage currents of annealed oxide were of two types: low and high leakage currents. The behavior of high leakage currents with applied voltage was similar to that of as-deposited oxide. For the explanation of these two kinds of leakage currents, it is shown that conduction mechanisms strongly related to oxide traps are not responsible for leakage currents, except space-charge-limited current (SCLC). From the applied voltage and temperature dependences of the current of the gate oxide, it is shown that the main conduction mechanisms for the two types of leakage current are SCLC and Schottky conductions at low and high applied voltages, respectively. The dielectric constant obtained from Schottky conduction was 27 and consistent with the C–V result. Based on SCLC theory, trap levels in the oxide band gap composed of both exponential and localized distributions were extracted using the differential method.

LaTiON/LaON as band-engineered charge-trapping layer for nonvolatile memory applications

“…6, where ln(J /E 2 ) varies linearly with E −1 . For the F-N tunneling, the current density can be expressed as [16] …”

Effects of sputtering pressure and post-metallization annealing on the physical properties of rf-sputtered Y2O3 films

“…The refractive index (n) of the samples become bigger after PMA treatment, and the mechanism is probably described as follows: the as-deposited films are always in loose arrangement with some voids incorporated during the sputtering, and the annealing procedure can eliminate some voids and activate the atoms to rearrange in the films, which leads to the formation of more closely packed films and correspondingly, the larger refractive index. Kim et al [25] also proved that low temperature annealing promoted thin film densification rather than cause the interfacial layer growth. This assumption is also confirmed by Drude equation, from which the calculated porosity values for 300 • C, 350 • C and 400 • C PMA treated samples are 9.7%, 9.6% and 9.5%, respectively, while for the as-deposited one, the calculated p is 10.5%.…”

“…Furthermore, the leakage current mechanism is discussed to interpret the conduction behavior. The space-charge-limited current (SCLC) model has been developed to describe the current behavior of numerous thin films, such as organic materials, nitride, and rare earth oxides [25]. A plot of J vs. E 2 should be linear for SCLC mechanism as determined from Mott-Gurney Law [36]:…”

DC-conduction mechanism in crystalline oxidised La and La–Mn films grown on p-Si substrate

“…However, still little is known about the mechanism of leakage current transfer in La 2 O 3 films grown on Si substrates, although, a few investigations have been recently carried out on ultrathin films prepared by electron-beam evaporation technique [6,7,21]. For vacuum- [7] and nitrogen-annealed [6] La 2 O 3 film, it was reported that the Al-gate-voltage dependence of the leakage current was governed by the space-charge-limited-current (SCLC)-or Poole-Frenkel (PF)-conduction mechanism.…”