No abstract

Resistive random access memory (ReRAM) devices with a HfO 2 dielectric layer have been studied extensively owing to the good reproducibility of their SET/RESET switching properties. Furthermore, it was reported that a thin Hf layer next to a HfO 2 layer stabilized switching properties because of the oxygen scavenging effect. In this work, we studied the Hf thickness dependence of the resistance switching characteristics of a Ti/Hf/HfO 2 /Au ReRAM device. It is found that the optimum Hf thickness is approximately 10 nm to obtain good reproducibility of SET/RESET voltages with a small RESET current. However, when the Hf thickness was very small (>2 nm), the device failed after the first RESET process owing to the very large RESET current. In the case of a very thick Hf layer (>20 nm), RESET did not occur owing to the formation of a leaky dielectric layer. We observed the occurrence of multiple resistance states in the RESET process of the device with a Hf thickness of 10 nm by increasing the RESET voltage stepwise.

Optical waveguide loss of about 0.55 dB cm−1 has been measured on epitaxial ZnO films on sapphire by magnetron sputtering. Measurements were also made of the refractive index of those films. The experimental results are compared with theory when TE and TM guided waves propagate in the plane at an arbitrary angle with respect to the c axis where the c axis is lying in the plane of the film. Surface acoustic wave (SAW) properties were also measured for SAW propagating along the c axis of ZnO film on the (011̄2)-oriented Al2O3 substrate.

Acoustooptic Bragg deflectors (ABDs) with high diffraction efficiencies were fabricated using ZnO thin films deposited on sapphire, glass, and Si substrates by an RF magnetron sputtering system. Optical waveguide losses of the ZnO films were about 0.5 dBcm(-1). Diffraction efficiencies of 95 and 98% for the TE(0) mode beam (at 632.8 nm) were accomplished by acoustic powers of 90 mW in a ZnO film on glass and 80 mW in a ZnO film on Si, respectively. The diffraction efficiencies of the ABD using a ZnO film on sapphire with interdigital transducers of different Q values and with the surface-acoustic-wave propagating along and perpendicular to the c -axis of the ZnO film were also determined.

We report TaC x /HfSiON gate stack CMOS device with simplified gate 1 st process from the viewpoints of fixed charge generation and its impact on the device performance. Moderate