Search results for "dga"
showing 10 items of 134 documents
Zvaigžņotā Debess: 2007/08, Ziema
2007
Latvijas Zinātnes padome, Latvijas Universitāte
Edgar Varèse y Julio González; algo más que un intercambio epistolar
2010
Zvaigžņotā Debess: 60.gadskārta
2019
Contents: In Remembrance of Jānis Ikaunieks, Arturs Balklavs and Andrejs Alksnis: I.Pundure. «ZVAIGŽŅOTĀ DEBESS» Was Leading to the Truth … ; I.Pundure. Astronomers of Latvian Origin in IAU Management ; DISCOVERIES: I.Pundure. Gaia’s Most Accurate Star Map of Milky Way and Its Surroundings ; SPACE RESEARCH and EXPLORATION: I.Pundure. ESA Selects Three New Missions to Explore the Universe ; LATVIAN SCIENTISTS: The List of Popular Science Papers (1958-2016) by Professor Andrejs Alksnis (concluded) ; In memoriam: Dr.sc.ing. Edgars Bervalds (1936-2019) ; In memoriam: Dr.phys. Natālija Cimahoviča (1926-2019) ; FLASHBACK: I.Pundure. On Hawking’s Publication in the Vatican’s Commentarii Series ; F…
Zinātņu vēsture un muzejniecība (Latvijas Universitātes Raksti, 809. sēj.)
2015
Resistive switching behaviour in ZnO and VO 2 memristors grown by pulsed laser deposition
2014
The resistive switching behaviour observed in microscale memristors based on laser ablated ZnO and VO 2 is reported. A comparison between the two materials is reported against an active device size. The results show that devices up to 300 × 300 μm 2 exhibit a memristive behaviour regardless of the device size, and 100 × 100 μm 2 ZnO-based memristors have the best resistance off/on ratio.
“Poe and Popular Culture”
2002
Zvaigžņotā Debess: 2006, Vasara
2006
Latvijas Zinātnes padome, Latvijas Universitāte
Growth and characterization of ZnO1−xSx highly mismatched alloys over the entire composition
2015
Alloys from ZnO and ZnS have been synthesized by radio-frequency magnetron sputtering over the entire alloying range. The ZnO1−xSx films are crystalline for all compositions. The optical absorption edge of these alloys decreases rapidly with small amount of added sulfur (x ∼ 0.02) and continues to red shift to a minimum of 2.6 eV at x = 0.45. At higher sulfur concentrations (x > 0.45), the absorption edge shows a continuous blue shift. The strong reduction in the band gap for O-rich alloys is the result of the upward shift of the valence-band edge with x as observed by x-ray photoelectron spectroscopy. As a result, the room temperature bandgap of ZnO1−xSx alloys can be tuned from 3.7 eV to …
Mechanochemical Synthesis of Sn(II) and Sn(IV) Iodide Perovskites and Study of Their Structural, Chemical, Thermal, Optical and Electrical Properties
2019
Phase‐pure CsSnI3, FASnI3, Cs(PbSn)I3, FA(PbSn)I3 perovskites (FA = formamidinium = HC(NH2)2+) as well as the analogous so‐called vacancy‐ordered double perovskites Cs2SnI6 and FA2SnI6 are mechanochemically synthesized. The addition of SnF2 is found to be crucial for the synthesis of Cs‐containing perovskites but unnecessary for hybrid ones. All compounds show an absorption onset in the near‐infrared (NIR) region, which makes them especially relevant for photovoltaic applications. The addition of Pb(II) and SnF2 is crucial to improve the electronic properties in 3D Sn(II)‐based perovskites, in particular their charge carriers mobility (≈0.2 cm2 Vs−1) which is enhanced upon reduction of the …
Efficient wide band gap double cation – double halide perovskite solar cells
2017
In this work we study the band gap variation and properties of the perovskite compound Cs0.15FA0.85Pb(BrxI1−x)3 as a function of the halide composition, with the aim of developing an efficient complementary absorber for MAPbI3 in all-perovskite tandem devices. We have found the perovskite stoichiometry Cs0.15FA0.85Pb(Br0.7I0.3)3 to be a promising candidate, thanks to its band gap of approximately 2 eV. Single junction devices using this perovskite absorber lead to a maximum PCE of 11.5%, among the highest reported for solar cells using perovskites with a band gap wider than 1.8 eV.