Search results for "dga"

The influence of AlN buffer over the polarity and the nucleation of self-organized GaN nanowires

2015

We experimentally investigate the influence of AlN buffer growth on the nucleation and the polarity of a self-organized assembly of GaN nanowires (NWs) grown on Si. Two complementary growth mechanisms for AlN buffer deposited on Si are demonstrated. Both emphasize the aggregation of Si on the AlN surface and the growth of large cubic crystallites, namely, AlN pedestals. Further growths of GaN NWs assembly reveal that the GaN 2D layer found at the bottom of the NW assembly is the result of the coalescence of Ga-polar pyramids, whereas AlN pedestals are observed as preferential but not exclusive NW nucleation sites. NWs are N-polar or exhibit inversion domains with a Ga-polar core/N-polar she…

Phase segregation in Mg$_{x}$Zn$_{1-x}$O probed by optical absorption and photoluminescence at high pressure

2017

The appearance of segregated wurtzite Mg$_x$Zn$_{1-x}$O with low Mg content in thin films with $x>0.3$ affected by phase separation, cannot be reliably probed with crystallographic techniques owing to its embedded nanocrystalline configuration. Here we show a high-pressure approach which exploits the distinctive behaviors under pressure of wurtzite Mg$_x$Zn$_{1-x}$O thin films with different Mg contents to unveil phase segregation for $x>0.3$. By using ambient conditions photoluminescence (PL), and with optical absorption and PL under high pressure for $x=0.3$ we show that the appearance of a segregated wurtzite phase with a magnesium content of x $\sim$ 0.1 is inherent to the wurtzit…

Photo-electrical and transport properties of hydrothermal ZnO

2016

We performed the studies of optical, photoelectric, and transport properties of a hydrothermal bulk n-type ZnO crystal by using the contactless optical techniques: photoluminescence, light-induced transient grating, and differential reflectivity. Optical studies revealed bound exciton and defect-related transitions between the donor states (at ∼60 meV and ∼240 meV below the conduction band) and the deep acceptor states (at 0.52 eV above the valence band). The acceptor state was ascribed to VZn, and its thermal activation energy of 0.43 eV was determined. A low value of carrier diffusion coefficient (∼0.1 cm2/s) at low excitations and temperatures up to 800 K was attributed to impact the rec…

High‐Quality Si‐Doped β‐Ga 2 O 3 Films on Sapphire Fabricated by Pulsed Laser Deposition

2020

The EU Horizon 2020 project CAMART2 is acknowledged for partly supporting the project, and the Ion Technology Centre, ITC, in Sweden is acknowledged for ion beam analysis (ERDA).

Optical properties and microstructure of 2.02-3.30 eV ZnCdO nanowires: effect of thermal annealing

2013

International audience; ZnCdO nanowires with up to 45% Cd are demonstrated showing room temperature photoluminescence (PL) down to 2.02 eV and a radiative efficiency similar to that of ZnO nanowires. Analysis of the microstructure in individual nanowires confirms the presence of a single wurtzite phase even at the highest Cd contents, with a homogeneous distribution of Cd both in the longitudinal and transverse directions. Thermal annealing at 550 C yields an overall improvement of the PL, which is blue-shifted as a result of the homogeneous decrease of Cd throughout the nanowire, but the single wurtzite structure is fully maintained.

Low-Power, Subthreshold Reference Circuits for the Space Environment : Evaluated with -rays, X-rays, Protons and Heavy Ions

2019

The radiation tolerance of subthreshold reference circuits for space microelectronics is presented. The assessment is supported by measured results of total ionization dose and single event transient radiation-induced effects under &gamma

Ernesta Foldāta vēstule draugiem LU Bioloģijas fakultātē 1995. gada 8. augustā

1995

Ernesta Foldāta vēstule draugiem Latvijas Universitātes Bioloģijas fakultātē, kurā viņš raksta par profesoru Edgaru Rutki un viņas sievas slimību un nāvi, savas ģimenes locekļu veselības stāvokļiem, grūto ekonomisko stāvokli Venecuēlā, dēlu grūtībām uzņēmuma vadīšanā, savu grāmatu izdošanu. Beigās novēlējumi un paraksts. Kopija vēstulei, kas drukāta mašīnrakstā uz vienas lapas. Glabājas Latvijas Universitātes Muzeja Botānikas un mikoloģijas kolekciju krājumā.

Latvijas Vēstures Institūta Žurnāls. 2015, Nr. 4 (97)

2015

Valsts kultūrkapitāla fonds

Carta de José Vidal Beneyto a Arcadi Espada a propósito de su artículo en El País (Cataluña) sobre la entrega del Premio Cataluña a Edgar Morin

1994

Multi-doped Brookite-Prevalent TiO2 Photocatalyst with Enhanced Activity in the Visible Light

2018

© 2018 Springer Science+Business Media, LLC, part of Springer Nature Abstract: Enabling solar and/or visible light-driven photocatalysis is a crucial step to access innovative applications in environmental science and sustainable energy. Titanium dioxide is the most used photocatalyst because of its low cost and toxicity, however it is also limitedly active under visible light irradiation due to its wide band gap. Among its polymorphs, brookite holds promising optoelectronic properties for visible light photocatalysis, which have to the best of our knowledge been limitedly exploited. Here, a C,S,N-doped brookite-based TiO2has been prepared via a rapid one-pot sol–gel synthesis. Besides subs…