We have previously reported (K,Na)NbO 3 (KNN) films, whose piezoelectric properties are the highest reported thus far. In this study, we investigate the detailed crystalline structures of these KNN films after deposition on Pt/MgO and Pt/Ti/SiO 2 / Si substrates by RF magnetron sputtering. The KNN film on Pt/MgO was epitaxially grown on the Pt lower electrode with a perfect h001i orientation in the perovskite structure. The KNN film on Pt/Ti/SiO 2 /Si was polycrystalline with a preferential h001i orientation in the perovskite structure having dense columnar grains. X-ray diffraction measurements revealed that the KNN films grown on Pt/MgO and Pt/Ti/SiO 2 /Si were tetragonal; the lattice parameters c and a were related as c=a > 1. The KNN film on Pt/MgO had a higher c=a value than the KNN film on Pt/Ti/SiO 2 /Si, indicating that the former had more compressed strain. We conclude that this difference in compressed strain may contribute to the difference in piezoelectric properties of the KNN films on Pt/MgO and Pt/Ti/SiO 2 /Si.

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The effects of the gas-flow-rate ratio on the electrical characteristics and the Fowler-Nordheim (FN) current stress resistance were investigated for Si oxynitride grown with helicon-wave excited (HWP) N2–Ar plasma. The flow-rate ratio of N2 [N2/(N2+Ar)] was varied from 100% (N2 only) to 60%. The X-ray photoelectron spectroscopic data (XPS) indicated that uniform Si oxynitride (probably Si2N2O) was formed through the entire film thickness when the N2 gas-flow-rate ratio was 100% (N2 only), though a small amount of Si suboxide was included. The capacitance–voltage (C–V) measurements revealed that the interface-state density was the lowest in this flow-rate ratio case, as the grown layer was postannealed at moderate temperatures (300–500°C). Fowler-Nordheim current injection was performed using the metal/Si-oxynitride/Si capacitors thus fabricated. The shift of the threshold voltage was the lowest for the sample grown without Ar mixing. It was smaller than that for the thermal Si oxide (SiO2) grown at 900°C. The results of FN current stress resistance experiments were explained in terms of the surface plasmon and avalanche breakdown models.

Pulsed Fowler–Nordheim (FN) current stress resistance was investigated for the Si oxynitride grown in the helicon-wave excited N2–Ar plasma. The shift of the gate threshold voltage Vth increased with an increase in the pulse frequency for both polarities of the applied stress voltage. At low frequencies (<1 kHz), the Vth shift was larger for the negative gate-voltage stress than for the positive one. However, as the frequency exceeds about 1 kHz, the Vth shift become much higher for the positive stress than for the negative one. The Vth shift was smaller as the pulse duty ratio was larger. These findings could be explained with the surface–plasmon and avalanche breakdown models combined with the effect of the total amount of the injected carriers to the oxynitride from the Si substrate or the gate electrode. The effect of Ar ion etching during plasma processing on the FN stress resistance was also investigated. The Ar ion etching effect was found to be substantially reduced as the plasma-sheath width was large and Si oxynitride samples were grown under this condition. The mean time to failure was highly improved by the Si oxynitride samples grown under the condition of reduced Ar ion etching effect.

Relatively thick amorphous silicon films for solar-cell applications were prepared by metal-induced-crystallization (MIC). Then, the thickness-dependent characteristics of microRaman spectra from a cross section of the prepared polycrystalline silicon (poly-Si) films were analyzed. It was found that Ni-induced crystallized films have a uniform composition that is 80% polycrystalline and 20% nanocrystalline. Also, the x-ray diffraction data show that a sub-mono-layer of Ni is sufficient for MIC of 6-µm-thick amorphous silicon (a-Si) films.