Kazuaki Deguchi

Verification of hot hole scattering rates in silicon by quantum-yield experiment

High-energy hole scattering rates for a full-band Monte Carlo simulation in Si are verified using a quantum-yield experiment. We compare two models that yield the correct drift velocity and ionization coefficient but quite different energy distributions. It is demonstrated that the quantum-yield experiment provides a means for monitoring hole scattering rates in Si; the model based on the ab initio impact ionization rate shows good agreement with the experiments, while the random-k approximation proposed by Kane overestimates the ionization rate of holes near the threshold energy.

Degradation of direct-tunneling gate oxide under hot-hole injection

The degradation of silicon-dioxide thin films induced by the hole direct-tunneling process is investigated using a substrate hot-hole (SHH) injection technique. Hot holes from the substrate, as well as cold holes in the inversion layer, are injected into the gate oxide in p-channel metal–oxide–semiconductor field-effect transistor with a p+ polycrystalline-silicon gate. The gate bias used is kept low enough to avoid simultaneous electron injection from the gate. During the SHH stress, in contrast to the case of thicker oxide films, a strong correlation is observed between the oxide film degradation and the injected hole energy, while no degradation occurs due to the direct tunneling of holes from the inversion layer. These experimental findings indicate the existence of threshold energy for the trap creation process, which has been predicted by the theoretical study of the hole-injection-induced structural transformation of oxygen vacancies in silicon dioxide.

Degradation of ultra-thin gate oxides accompanied by hole direct tunneling: can we keep long-term reliability of p-MOSFETs?

Degradation of ultra-thin gate oxide films accompanied by hole direct tunneling is investigated using a substrate hot hole injection technique. Although cold hole injection from the inversion layer of p-MOSFET does not affect the oxide reliability, the drastic degradation during the hot hole injection was observed. The new experimental findings on the hot-hole induced oxide degradation are well explained by the model of two-hole capture by an O vacancy.

Monte Carlo simulation of quantum yields exceeding unity as a probe of high-energy hole scattering rates in Si

High-energy hole scattering rates for a full band Monte Carlo simulation in Si are verified using the quantum-yield experiment. We compare two models that yield the correct velocity-field and ionization coefficient characteristics but quite different energy distributions. It is demonstrated that quantum yields exceeding unity can be used as a probe of hole scattering rates in Si; the model based on ab initio impact ionization rate shows goad agreement With the experiments.

Electroluminescence in ZnS1−xTex:CeF3 thin‐film devices

The effects of Te codoping in ZnS:CeF3 thin‐film electroluminescent devices are reported. ZnS1−xTex:CeF3 thin films are prepared at several Te concentrations and substrate temperatures. The emissive peak position and intensity depend on Te concentrations, substrate temperatures, the annealing, and drive voltages.

Carrier separation measurement of leakage current under prebreakdown in ultrathin SiO2 films

The anomalously large gate leakage current observed prior to dielectric breakdown in electrically stressed n+ gate p metal–oxide–semiconductor field-effect transistors is investigated. Carrier separation measurements reveal that the leakage currents are electron tunneling current, and in some cases are accompanied by noticeable hole-related current at low gate voltages. Experimental results demonstrate the close correlation between this phenomenon and soft breakdown in terms of current–voltage characteristics.