Angle-resolved X-ray photoelectron spectroscopy (ARXPS) and a modified Levenberg-Marquardt fit procedure: a new combination for modeling thin layers

The combination of angle-resolved X-ray photoelectron spectroscopy (ARXPS) and a modified Levenberg-Marquardt (LM) fit procedure has been used to study a native oxide layer on a clean Si(100) substrate. Numerical calculations show that with an aperture of 3° or 9° of the electron analyser, the photoelectron take-off angle should not exceed 80° or 70°, respectively, as compared to normal take-off angles. At larger photoelectron take-off angles, the effect of the aperture on the photoelectron energy distribution may not be neglected. We show how absolute ARXPS measurements in which the same XPS feature is considered at several electron take-off angles are an alternative for relative ARXPS film thickness measurements, avoiding large errors in the quantitative results. Models for the composition and thickness of the oxide layer have been developed. Also, the errors in the parameters of these models have been calculated. It can be concluded that the native oxide layer on silicon is 27 ± 1 (±-5%) Å thick and that the ratio of the silicon atom concentration in the substrate to that in the native oxide layer is 3.7 ±- 0.3 (±-8%), values that agree well with the literature. This report shows that the combination of ARXPS and a LM fit procedure is well suited to study ultra-thin layers and gives reliable results

Stofniveau biologische varkensstal onveilig hoog

Biologische varkenshouders werken vaak langdurig in de stal vanwege de grote zorg voor de dieren. Daarnaast is strooisel een vereiste in de biologische varkenshouderij. Dit leidt ertoe dat biologische varkenshouders aan hoge stofconcentraties worden blootgesteld. Wageningen UR Livestock Research onderzocht samen met biologische varkenshouders hoe hoog de stofbelasting is en hoe zij zich tegen het stof kunnen bescherme

Blootstelling aan fijnstof in de biologische varkenshouderij = Exposure to fine dust in organic pig farming

In deze studie zijn metingen verricht van de persoonlijke blootstelling aan fijnstof tijdens het werk op drie biologische varkensbedrijven. Uit de resultaten blijkt dat biologische varkenshouders bloot staan aan fijnstofconcentraties die aanzienlijk hoger zijn dan geadviseerde streefwaarden. Dit rapport geeft praktische aanbevelingen aan biologische varkenshouders om de blootstelling aan fijnstof tijdens het werk te verlage

Metal contacts to lowly doped Si and ultra thin SOI

We present our investigations on the fabrication of ohmic and Schottky contacts of several metals on lowly doped bulk Si and SOI wafers. Through this paper we evaluate the fabrication of rectifying devices in which no doping is intentionally introduced

Carbon Dioxide Production in Animal Houses: A literature review

This article deals with carbon dioxide production from farm animals; more specifically, it addresses the possibilities of using the measured carbon dioxide concentration in animal houses as basis for estimation of ventilation flow (as the ventilation flow is a key parameter of aerial emissions from animal houses). The investigations include measurements in respiration chambers and in animal houses, mainly for growing pigs and broilers. Over the last decade a fixed carbon dioxide production of 185 litres per hour per heat production unit, hpu (i.e. 1000 W of the total animal heat production at 20 oC) has often been used. The article shows that the carbon dioxide production per hpu increases with increasing respiration quotient. As the respiration quotient increases with body mass for growing animals, the carbon dioxide production per heat production unit also increases with increased body mass. The carbon dioxide production is e.g. less than 185 litres per hour per hpu for weaners and broilers and higher for growing finishing pigs and cows. The analyses show that the measured carbon dioxide production is higher in full scale animal houses than measured in respiration chambers, due to differences in manure handling. In respiration chambers there is none or very limited carbon dioxide contribution from manure; unlike in animal houses, where a certain carbon dioxide contribution from manure handling may be foreseen. Therefore, it is necessary to make a correction of data from respiration chambers, when used in full scale animal buildings as basis for estimation of ventilation flow. Based on the data reviewed in this study, we recommend adding 10% carbon dioxide production to the laboratory based carbon dioxide production for animal houses with slatted or solid floors, provided that indoor manure cellars are emptied regularly in a four weeks interval. Due to a high and variable carbon dioxide production in deep straw litter houses and houses with indoor storage of manure longer than four weeks, we do not recommend to calculate the ventilation flow based on the carbon dioxide concentration for these houses

Low-temperature process steps for realization of non-volatile memory devices

In this work, the low-temperature process steps required for the realization of nano-crystal non-volatile memory cells are discussed. An amorphous silicon film, crystallized using a diode pumped solid state green laser irradiating at 532 nm, is proposed as an active layer. The deposition of the subsequent functional layers (e.g., gate oxide) can be done using CVD and ALD reactors in a cluster tool. We show that a high nanocrystal density (Si-NC), required for a good functionality of the memory device, can be obtained by using disilane (Si2H6) or trisilane (Si3H8, known as Silcore®) as precursors for LPCVD instead of silane, at a deposition temperature of 325 °C. The nanocrystals are encapsulated with an ALD-Al2O3 layer (deposited at 300 °C), which serves as oxidation barrier. The passivation of the realized structure is done with an ALD-TiN layer deposited at 425 °C. In this work, we realized Al/TiN/Al2O3/Si-NC/SiO2/Si(100) multilayer floating-gate structures, where the crystallized amorphous silicon film was for the time being replaced by a mono-crystalline silicon wafer, and the gate oxide was thermally grown instead of a low-temperature PECVD oxide. The structures were characterized in terms of their performance as memory cells. In addition, the feasibility to use laser crystallization for improving the amorphous silicon films (prior to the gate oxide deposition) was explored

Measures to reduce fine dust emission from poultry houses: reduction from broiler houses by ionization

In this study the effect was determined of a commercially available air ionization system on the reduction of airborne dust in a broiler house. Results showed a reduction, based on particle mass, of 36% and 10% for PM10 and PM2.5, respectivel

Maatregelen ter vermindering van fijnstofemissie uit de pluimveehouderij: indicatieve evaluatie van het droogfiltersysteem StuffNix van Big Dutchman = Measures to reduce fine dust emission from poultry facilities: indicative evaluation of the Stuffnix system of Big Dutchman

In this study the StuffNix system of Big Dutchman is indicatively evaluated for its ability to remove fine dust from exhaust air. Results are inconclusive and indicate a removal efficiency in the range of 20 to 60%. Further research and validation measurements in practice are needed to determine removal with certaint

Slim Plakwerk

De techniek van ioniseren lijkt perspectiefvol tegen fijnstofemissie uit vleeskuikenstallen. Dit blijkt uit onderzoek op Het Spelderholt

Maatregelen ter vermindering van fijnstofemissie uit de pluimveehouderij: ontwikkeling van een oliefilmsysteem voor leghennen in volièrehuisvesting = Measures to reduce fine dust emission from poultry houses: development of an oil spraying system for layers in aviary housing

In phase one of this study an oil spraying system was developed for layers in aviary housing. In phase two the effect of the system on emissions of fine dust was determined. Emissions of PM10 and PM2,5 from the Big Dutchman aviary system were reduced by 18 and 65% respectively. No reductions were found for the Meller aviary. No effect was found on personal dust exposure or egg production. In the oil film rooms higher mortality was found. Further research is needed to clarify this