Optical trapping and manipulation of plasmonic nanoparticles: fundamentals, applications, and perspectives

This feature article discusses the optical trapping and manipulation of plasmonic nanoparticles, an area of current interest with potential applications in nanofabrication, sensing, analytics, biology and medicine. We give an overview over the basic theoretical concepts relating to optical forces, plasmon resonances and plasmonic heating. We discuss fundamental studies of plasmonic particles in optical traps and the temperature profiles around them. We place a particular emphasis on our own work employing optically trapped plasmonic nanoparticles towards nanofabrication, manipulation of biomimetic objects and sensing

Thixomolded AZ91D and MRI153M magnesium alloys and their enhanced corrosion resistance

© 2020 The Authors. Materials and Corrosion published by WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim AZ91D and MRI153M alloys were produced by thixomolding. Their corrosion resistance is significantly higher than that of similar materials produced by ingot or die-casting. A corrosion rate smaller than 0.2 mm/year in 5 wt% NaCl solution is measured for the thixomolded AZ91D alloy. The corrosion behaviour was evaluated using immersion tests, electrochemical impedance spectroscopy, hydrogen evolution, glow discharge optical emission spectroscopy, and atomic emission spectroelectrochemistry. A bimodal microstructure is observed for both alloys, with the presence of coarse primary α-Mg grains, fine secondary α-Mg grains, β-phase, and other phases with a minor volume fraction. The amount of coarse primary α-Mg is significantly higher for the AZ91D compared with the MRI153M. The network of β-phase around the fine secondary α-Mg grains is better established in the thixomolded AZ91D alloy. A combination of several factors such as the ratio of primary to secondary α-Mg grains, localised corrosion or barrier effect due to other phases, as well as regions of preferential dissolution of the α-Mg due to chemical segregation, are thought to be responsible for the high corrosion resistance exhibited by the thixomolded AZ91D and MRI153M.German Ministry of Education and Research; Christian Doppler Societ

Pripper: prediction of caspase cleavage sites from whole proteomes

Peer reviewe

Transfer of POCl3 diffusion processes from atmospheric pressure to high throughput low pressure

We transfer an industrial-type atmospheric pressure (AP) diffusion process using phosphorus oxychloride (POCl3) with short in-situ oxidation to a low-pressure (LP) system which allows significantly higher throughput. We demonstrate low emitter dark saturation current density j0e ≈ 45 fA/cm2 (texture, SiNX passivation) for optimized LP-POCl3 diffusion at 110 Ω/sq sheet resistance. Examinations of the glass layer grown on the silicon surface during POCl3 diffusion show a similar two layer system, i.e. phosphosilicate glass and silicon dioxide, for AP-POCl3 and LP-POCl3 diffusions. Industrial p-type Czochralski-grown silicon passivated emitter and rear solar cells yield peak energy conversion efficiencies of 21.1% for both AP- and LP-POCl3-diffused emitters

Inline Deposited PassDop Layers for Rear Side Passivation and Contacting of p-type c-Si PERL Solar Cells with High Bifaciality

We investigate stacks of aluminum oxide (Al2O3) and boron-doped silicon nitride (SiNX:B) layers for the rear side passivation and local doping of p-type silicon solar cell samples aiming for the realization of bifacial passivated emitter and rear locally diffused (biPERL) solar cells. The local p+-doped back surface field regions are formed by laser doping and are electrically contacted using commercially available screen-printed and fired silver-aluminum (AgAl) or silver (Ag) contacts. This approach is referred to as “pPassDop”. Laser doping results in highly-doped silicon with sheet resistances as low as 15 Ω/sq and surface doping concentrations up to 6×1019 cm−3. Low specific contact resistances around 1 mΩ cm2 and 5 mΩ cm2 are measured for the screen-printed and fired AgAl and Ag contacts, respectively. In addition, the influence of each individual layer within the pPassDop layer stack on the doping properties is investigated. In order to separate the impact of aluminum and boron doping, firstly the influence of the Al2O3 layer thickness (0 nm, 4 nm, 6 nm) below the SiNX:B capping layer is studied. Secondly, a conventional undoped SiNX capping layer is applied on a 6 nm-thick Al2O3 layer. The roles of each dopant are studied by measuring the doping profile and contact resistivity

Control of boron diffusion from APCVD BSG layers by interface oxidation

We investigate the impact of oxygen concentration during boron diffusion at peak temperatures varying from 875°C to 950°C using borosilicate glass layers (BSG) deposited by atmospheric pressure chemical vapor deposition (APCVD) as doping source. Therefore, we vary the boron concentration in the BSG layer and the oxygen concentration in the gaseous ambient of the high temperature step. We characterize the process combinations with respect to their resulting sheet resistance and charge carrier concentration profile. In addition, we perform quasi steady-state photoconductance measurements to investigate the influence of the process parameters on the recombination properties at the boron-diffused and passivated surface. Low saturation current densities J0 = 16 fA/cm2 (planar surface, Al2O3/SiNx passivation) are observed at a sheet resistance of Rsh = 121 Ω/sq at peak temperature Tpeak = 875°C. Finally, we show that the oxygen concentration is a crucial parameter to prevent the formation of a boron rich layer at the silicon surface. This parameter needs to be selected carefully, as too high oxygen concentrations lead to complete decoupling of the doping source, depending on boron concentration and process temperature