Abstract-Germanium based photonic devices can play a significant role in several applications, particularly in the socalled fingerprint wavelength region. Here, we review our recent results on mid-infrared germanium photonic devices that show promising performance in the 2-7.5 µm wavelength range.

Abstract-Top-down fabrication is used to produce ZnO nanowires by remote plasma atomic layer deposition over a SiO 2 pillar and anisotropic dry etching. Nanowire field-effect transistors (FETs), with channel lengths in the range of 1.3-18.6 µm, are then fabricated using these 80 nm × 40 nm nanowires. Measured electrical results show n-type enhancement behavior and a breakdown voltage ≥75 V at all channel lengths. This is the first report of high-voltage operation for ZnO nanowire FETs. Reproducible well-behaved electrical characteristics are obtained, and the drain current scales with 1/L, as expected for long-channel FETs. A respectable I ON /I OFF ratio of 2 × 10 6 is obtained.Index Terms-Atomic layer deposition (ALD), field-effect transistor (FET), nanowire, remote plasma, top-down fabrication, ZnO.

a b s t r a c tThis paper describes a systematic approach to analyze the simultaneous impact of various reactant plasma parameters of remote plasma enhanced ALD (PEALD) on the ZnO thin film properties. Particular emphasis is placed on the film stoichiometry which affects the electrical properties of the thin film. Design of Experiment (DOE) is used to study the impact of the oxygen plasma parameters such as the RF power, pressure and plasma time to realize semiconductor quality of ZnO thin film. Based on the optimized plasma condition, staggered bottom-gate TFTs were fabricated and its electrical characteristics were measured.

We fabricated and measured the optical loss of polysilicon waveguides deposited using hot-wire chemical vapor deposition at a temperature of 240°C. A polysilicon film 220 nm thick was deposited on top of a 2000 nm thick plasma-enhanced chemical vapor deposition silicon dioxide layer. The crystalline volume fraction of the polysilicon film was measured by Raman spectroscopy to be 91%. The optical propagation losses of 400, 500, and 600 nm waveguides were measured to be 16.9, 15.9, and 13.5 dB∕cm, respectively, for transverse electric mode at the wavelength of 1550 nm. Scattering loss is expected to be the major contributor to the propagation loss.

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