Influence of substrate bias on the structural and dielectrical properties of magnetron-sputtered BaxSr1-xTiO3 thin films

The application of a substrate bias during rf magnetron sputtering alters the crystalline structure, grain morphology, lattice strain and composition of BaxSr1-xTiO3 thin films. As a result, the dielectric properties of Pt/BaxSr1-xTiO3/Pt parallel-plate capacitors change significantly. With increasing substrate bias we observe a clear shift of the ferroelectric to paraelectric phase transition towards higher temperature, an increase of the dielectric permittivity and tunability at room temperature, and a deterioration of the dielectric loss. To a large extent these changes correlate to a gradual increase of the tensile in-plane film strain with substrate bias and an abrupt change in film composition.Comment: 24 pages, 8 figures, submitted to Ferroelectric

Tilannejohtaminen ja potilasturvallisuus hätätilapotilaan tunnistamisessa ja hoitamisessa ABCDE-mallin mukaisesti : -Opetusvideo Karelia-ammattikorkeakoulun hoitotyön opiskelijoille

Tilannejohtamisen ja potilasturvallisuuden osaaminen hätätilapotilaan tunnistamisessa ja hoitamisessa sekä systemaattisessa tutkimisessa on tärkeää hoitotyön opiskelijoille. Kaikkien sairaanhoitajien tulisi tunnistaa varoitusmerkit potilaan voinnin huononemisesta sekä pystyä aloittamaan tilanteen mukainen hoito. Tämän opinnäytetyön tarkoituksena oli lisätä hoitotyön opiskelijoiden tietoutta hätätilapotilaan systemaattisesta tutkimisesta ja hoitamisesta sekä siihen liittyvistä muistisäännöistä ja opettaa tilannejohtajuutta ja potilasturvallisuutta hätätilapotilaan tutkimisen ja hoitamisen aikana. Opinnäytetyön tehtävänä oli tuottaa hoitotyön opiskelijoille opetusvideo tilannejohtamisesta ja potilasturvallisuudesta hätätilapotilaan tunnistamisessa ja hoitamisessa ABCDE-mallin mukaisesti. Tämän toiminnallisen opinnäytetyön toimeksiantajana oli Karelia-ammattikorkeakoulu. Tavoitteena on, että opetusvideota voidaan hyödyntää hoitotyönkoulutuksessa yhtenä opetusmenetelmänä, ja se toimisi opiskelijoille oppimisen apuvälineenä. Videosta pyydettiin palautetta toimeksiantajalta kirjallisena sekä hoitotyön opiskelijoilta kyselylomakkeella. Palautteen perusteella jatkokehittämisideoina opinnäytetyölle on tehdä mahdollisimman oikeita tilanteita kuvaavia opetusvideoita, joita voisi käyttää opetuksessa enemmän. Sekä opetusvideoiden toimivuutta voi tutkia opetuksessa

Characterisation of an epitaxial GaAs/Medipix2 detector using fluorescence photons

Abstract A high-purity GaAs sensor of 110 μm thickness has been bump bonded to a Medipix2 readout chip. The room temperature spectroscopic response of this device to fluorescence photons in the energy range from 8 to 28 keV is presented and compared to the response of a 300 μm thick Si sensor, also bonded to a Medipix2 chip. The measured photopeak responses are used to calibrate both detectors. The depth of depletion of the GaAs sensor is estimated to be 50 μm at 140 V sensor bias voltage from measurements made using the 8 keV Kα line of a Cu target X-ray tube

GaAs Medipix2 hybrid pixel detector

A GaAs Medipix2 hybrid pixel detector based on high purity epitaxial GaAs material was successfully fabricated. The mesa type GaAs sensor with 256×256 pixels and total area of 1.4×1.4 cm2 was made of a 140-μm-thick epitaxial p–i–n structure utilizing reactive ion etching. A final thickness of approximately 110 μm for the all-epitaxial sensor element is achieved by back-thinning procedure. The sensor element is bump bonded to a Medipix2 read-out ASIC. The detector is capable of room temperature spectroscopic operation and it demonstrates the potential of GaAs for high resolution X-ray imaging systems operating at room temperature. This work describes the manufacturing process and electrical properties of the GaAs Medipix2 hybrid detector

InAs-Al Hybrid Devices Passing the Topological Gap Protocol

We present measurements and simulations of semiconductor-superconductor heterostructure devices that are consistent with the observation of topological superconductivity and Majorana zero modes. The devices are fabricated from high-mobility two-dimensional electron gases in which quasi-one-dimensional wires are defined by electrostatic gates. These devices enable measurements of local and non-local transport properties and have been optimized via extensive simulations for robustness against non-uniformity and disorder. Our main result is that several devices, fabricated according to the design's engineering specifications, have passed the topological gap protocol defined in Pikulin {\it et al.}\ [arXiv:2103.12217]. This protocol is a stringent test composed of a sequence of three-terminal local and non-local transport measurements performed while varying the magnetic field, semiconductor electron density, and junction transparencies. Passing the protocol indicates a high probability of detection of a topological phase hosting Majorana zero modes. Our experimental results are consistent with a quantum phase transition into a topological superconducting phase that extends over several hundred millitesla in magnetic field and several millivolts in gate voltage, corresponding to approximately one hundred micro-electron-volts in Zeeman energy and chemical potential in the semiconducting wire. These regions feature a closing and re-opening of the bulk gap, with simultaneous zero-bias conductance peaks at {\it both} ends of the devices that withstand changes in the junction transparencies. The measured maximum topological gaps in our devices are 20-$30\,\mu$eV. This demonstration is a prerequisite for experiments involving fusion and braiding of Majorana zero modes.Comment: Fixed typos. Fig. 3 is now readable by Adobe Reade