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The applications of a boron-doped diamond (BDD) used in electrode application for toxic and refractory organic degradation have attracted much attention, and its efficiency is considered to be an important factor for its practical application. In this study, BDD thin films were prepared on Ti plates by double bias-assisted hot filament chemical vapor deposition (HFCVD) technique. A reactive ion etching process was introduced by a positive grid bias and a negative substrate bias which can generate an electric field in HFCVD system. Then a novel structure of BDD electrode with nanocone arrays was successfully etched from a flat diamond thin film by this system. The addition of the bias greatly improved the etching efficiency and promoted the formation of nanocones structures. The cyclic voltammograms (CV) test showed nanostructured BDD (NBDD) electrodes had excellent electrochemical performance almost the same as that of the electrodes with untreated surfaces. It had a large effective electroactive surface area (EASA), which was 31.0% greater than the unetched electrode. As a result, the NBDD electrode exhibited improved electrocatalytic performance as compared with the untreated one, i.e., an about 24.3% increase of chemical oxygen demand (COD) removal efficiency. Among them, the superiority of NBDD electrode was obvious in the initial stage due to its highest concentration in the initial stage. In addition, the NBDD electrode achieved higher average current efficiency (ACE) as compared with the untreated one. Unlabelled Image • The BDD nanostructure was prepared by double bias-assisted HFCVD system. • The NBDD films were used as electrodes for wastewater treatment. • The EASA of the NBDD electrodes was increased. • The COD removal rate and ACE of NBDD electrodes were improved. [ABSTRACT FROM AUTHOR]

With the development of new designs and materials for nano-scale transistors, vertical Gate-All-Around Field Effect Transistors (vGAAFETs) with germanium as channel materials have emerged as excellent choices. The driving forces for this choice are the full control of the short channel effect and the high carrier mobility in the channel region. In this work, a novel process to form the structure for a VGAA transistor with a Ge channel is presented. The structure consists of multilayers of Si0.2Ge0.8/Ge grown on a Ge buffer layer grown by the reduced pressure chemical vapor deposition technique. The Ge buffer layer growth consists of low-temperature growth at 400 °C and high-temperature growth at 650 °C. The impact of the epitaxial quality of the Ge buffer on the defect density in the Si0.2Ge0.8/Ge stack has been studied. In this part, different thicknesses (0.6, 1.2 and 2.0 µm) of the Ge buffer on the quality of the Si0.2Ge0.8/Ge stack structure have been investigated. The thicker Ge buffer layer can improve surface roughness. A high-quality and atomically smooth surface with RMS 0.73 nm of the Si0.2Ge0.8/Ge stack structure can be successfully realized on the 1.2 µm Ge buffer layer. After the epitaxy step, the multilayer is vertically dry-etched to form a fin where the Ge channel is selectively released to SiGe by using wet-etching in HNO3 and H2O2 solution at room temperature. It has been found that the solution concentration has a great effect on the etch rate. The relative etching depth of Ge is linearly dependent on the etching time in H2O2 solution. The results of this study emphasize the selective etching of germanium and provide the experimental basis for the release of germanium channels in the future. [ABSTRACT FROM AUTHOR]