Search

We have investigated the structural and electrical properties of the metal/ferroelectric/insulator/semiconductor (MFIS) structure that incorporates a MgO/SiO2 insulating buffer between a ferroelectric layer and Si substrate. Highly oriented lead–zirconate–titanate [Pb(Zr,Ti)O3, or PZT] films were grown on the MgO-buffered oxidized silicon substrates with a rf magnetron sputtering technique. The x-ray diffraction and energy-dispersive x-ray spectroscopy analysis results show that a MgO buffer serves well not only as a template layer for growing oriented PZT films on an amorphous surface but also as a diffusion barrier between PZT and Si substrates. The memory window of the MFIS structure was characterized with a capacitance-versus-voltage method. Numerical analyses were also carried out to simulate the MFIS capacitor characteristics. In this simulation, the PZT films were assumed to have a two-layer structure in which the dielectric and ferroelectric properties of an initial layer are significantly weaker ...

We have investigated the effects of oxygen plasma treatment on the UV detection properties of ultrathin (∼20-nm-thick) ZnO epitaxial films. Highly epitaxial ZnO films grown on sapphire were exposed to oxygen-radical-rich, inductively coupled plasma, and then their UV detection properties were characterized at 325 nm wavelength using a photoconductor structure. The oxygen plasma treatment is found to dramatically enhance the UV detection properties of ZnO, reducing the decay time constant (to below 50 μs) and increasing the on/off ratio of photocurrent (to over 1000) with high UV responsivity (1–10 A/W). This result, in conjunction with the microstructural and electrical characterization results, indicates that the plasma treatment efficiently suppresses the chemisorption sites (primarily the oxygen deficiency sites) on surface and also the oxygen vacancies in ZnO, therefore results in major reduction of the chemisorption effects and the dark current, respectively.

In this paper we report the energy spectra of single electrons confined in a single InAs quantum dot, and single holes confined in a single GaSb quantum dot. These quantum dots are fabricated by laterally reducing the diameter of resonant tunneling (or resonant interband tunneling) diodes. The dc current‐voltage characteristics at 4.2K is taken by a cryogenic scanning probe, that during measurement is in direct physical contact with the top electrode.