Yongshik Kim

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

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.

Space-charge-limited current conductions in La/sub 2/O/sub 3/ thin films deposited by e-beam evaporation after low temperature dry-nitrogen annealing [gate oxide applications]

Lanthanum oxide (La/sub 2/O/sub 3/) was deposited by e-beam evaporation on n-Si(100), and annealed at 200/spl deg/C in dry-nitrogen ex-situ for 5 min. From the applied voltage and temperature dependences of the current of the gate oxide, it has been shown that the main conduction mechanisms are SCLC (space-charge-limited current) and Schottky conductions at low and high applied voltages, respectively. Trap levels in the oxide band gap, composed of both exponential and localized distributions, were extracted by using the differential method. The dielectric constant obtained from Schottky conduction was 27 and was consistent with the C-V results.

Analysis of electrical characteristics of La/sub 2/O/sub 3/ thin films annealed in vacuum and others

Lanthanum oxide (La/sub 2/O/sub 3/) was deposited by MBE on n-Si(100), and annealed at 400/spl deg/C in vacuum in-situ for 90 min. Ag or Al metal electrodes were attached. From the electric field and temperature dependence of the current of the gate oxide, it has been shown that the main conduction mechanism is the P-F (Poole-Frenkel) conduction and contributed by the SCLC (space-charge-limited current), depending on the bias conditions. The dielectric constant obtained from the P-F conduction equation was 10 and was consistent with the C-V result. We also realized that SCLC plays a role in the low gate voltage region of the P-F conduction, which ranges in an absolute voltage less than 0.34 V.