A Ge/Si heterojunction L-shaped tunnel field-effect transistor combined with hetero-gate-dielectric (GHL-TFET) is proposed and investigated by TCAD simulation. Current-voltage characteristics, energy-band diagrams, and the distribution of the band-to-band tunneling (BTBT) generation rate of GHL-TFET are analyzed. In addition, the effect of the vertical channel width on the ON-current is studied and the thickness of the gate dielectric is optimized for better suppression of ambipolar current. Moreover, analog/RF figure-of-merits of GHL-TFET are also investigated in terms of the cut-off frequency and gain bandwidth production. Simulation results indicate that the ON-current of GHL-TFET is increased by about three orders of magnitude compared with that of the conventional L-shaped TFET. Besides, the introduction of the hetero-gate-dielectric not only suppresses the ambipolar current effectively but also improves the analog/RF performance drastically. It is demonstrated that the maximum cut-off frequency of GHL-TFET is about 160 GHz, which is 20 times higher than that of the conventional L-shaped TFET.

Growth and structural properties of thin a-C films prepared by the 60 MHz very-high-frequency (VHF) magnetron sputtering were investigated. The energy and flux of ions impinging the substrate were also analyzed. It is found that the thin a-C films prepared by the 60 MHz sputtering have a lower growth rate, a smooth surface, and more sp 3 contents. These features are related to the higher ion energy and the lower ions flux onto the substrate. Therefore, the 60 MHz VHF sputtering is more suitable for the preparation of thin a-C film with more sp 3 contents.

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ZnO and ZnO-Al 2 O 3 thin films were prepared by dc magnetron sputtering and their structural, optical and electrical properties were studied comparatively. It is discovered that the ZnO-Al 2 O 3 thin films remain transparent in a shorter wavelength range than the ZnO films, resulting from the increase of their band gap. Their resistivity decreases by seven orders of magnitude, which is caused by doping of Al to ZnO grains in the film. Preferential orientation of ZnO grains in the ZnO-Al 2 O 3 thin films deteriorates because of the existence of Al 2 O 3 impurity phase in the film. 68.55; 78.65; 73.60 ZnO thin films have many practical applications owing to their interesting properties. They are used in various pressure transducers, acoustic wave and acoustic-optical devices with their piezoelectric properties [1,2]. They are useful as transparent electrodes in panel displays and solar cells while doped with Al, In etc., and as catalytic combustion sensors while doped with Pt and Pd [3]. PACS:Another important application of ZnO films is the use as a buffer layer for the growth of GaN films. Recently, improvement of the GaN blue light-emitting diode [4] has made it possible to display full color by semiconductor [5]. One of the problems that has plagued further development of GaN film is lack of high-quality, closely lattice-matched substrate materials [6]. People often deposited GaN films on sapphire substrate although it has large lattice dismatch and thermal expansion. ZnO is closely lattice matched to GaN and has the same crystal structure. Therefore, the ZnO film offers the potential to be a substrate on which high-quality GaN films may be grown.As the development in flat panel displays frequently requires the improvement of electrical, optical, and chemical properties of the transparent electrodes, scientists are searching for new materials consisting of ternary or multicomponent oxides suitable for special applications. In 2 O 3 -SnO and ZnO:Al films have received much attention [7,8]. ZnO:Al films have the advantages that they can be produced at low substrate temperature and etched easily. But many research works focus on low Al content in ZnO films.This paper reports the preparation of ZnO-Al 2 O 3 and pure ZnO films by dc magnetron sputtering. The structural, optical, and electrical properties were compared between these two kinds of films. The possibility of ZnO-Al 2 O 3 films as a buffer layer and transparent electrodes of blue emitter diode is discussed. ExperimentSputtering targets were made from pressing pure Zn powder and Zn/Al(1:1) premixed powder, respectively, under the pressure of 6 × 10 8 Pa. The targets were then calcined in a vacuum furnace at 420 • C for 4 h, then polished and cleaned for sputtering. Intrinsic silicon and quartz glass plates were cleaned by alcohol in a supersonic wave apparatus and used as substrate.The ZnO and ZnO-Al 2 O 3 thin films were prepared by conventional planar magnetron sputtering. The deposition was carried out under dc power of 25 W, in an Ar and O 2 ambien...

The growth and structural properties of Ag films prepared by radio-frequency (2, 13.56 and 27.12 MHz) and very-high-frequency (40.68 and 60 MHz) magnetron sputtering were investigated. Using 2 MHz sputtering, the Ag film has a high deposition rate, a uniform and smooth surface and a good fcc structure. Using 13.56 and 27.12 MHz sputtering, the Ag films still have a high deposition rate and a good fcc structure, but a non-uniform and coarse surface. Using 40.68 MHz sputtering, the Ag film has a moderate deposition rate and a good fcc structure, but a less smooth surface. Using 60 MHz sputtering, the Ag film has a uniform and smooth surface, but a low deposition rate and a poor fcc structure. The growth and structural properties of Ag films are related to the ions' energy and flux density. Therefore, changing the driving frequency is a good way to control the growth and structure of the Ag films.