Moderate temperature deposition of RF magnetron sputtered SnO2-based electron transporting layer for triple cation perovskite solar cells.

The perovskite solar cells (PSCs) are still facing the two main challenges of stability and scalability to meet the requirements for their potential commercialization. Therefore, developing a uniform, efficient, high quality and cost-effective electron transport layer (ETL) thin film to achieve a stable PSC is one of the key factors to address these main issues. Magnetron sputtering deposition has been widely used for its high quality thin film deposition as well as its ability to deposit films uniformly on large area at the industrial scale. In this work, we report on the composition, structural, chemical state, and electronic properties of moderate temperature radio frequency (RF) sputtered SnO2. Ar and O2 are employed as plasma-sputtering and reactive gases, respectively. We demonstrate the possibility to grow a high quality and stable SnO2 thin films with high transport properties by reactive RF magnetron sputtering. Our findings show that PSC devices based on the sputtered SnO2 ETL have reached a power conversion efficiency up to 17.10% and an average operational lifetime over 200 h. These uniform sputtered SnO2 thin films with improved characteristics are promising for large photovoltaic modules and advanced optoelectronic devices.

Study of wide bandgap SnOx thin films grown by a reactive magnetron sputtering via a two-step method.

In the present work, we report on the microstructural and optoelectronic properties of SnOx thin films deposited by a reactive radio frequency magnetron sputtering. After SnOx growth by sputtering under O2/Ar flow, we have used three different treatment methods, namely (1) as deposited films under O2/Ar, (2) vacuum annealed films ex-situ, and (3) air annealed films ex-situ. Effects of the O2/Ar ratios and the growth temperature were investigated for each treatment method. We have thoroughly investigated the structural, optical, electrical and morphology of the different films by several advanced techniques. The best compromise between electrical conductivity and optical transmission for the use of these SnOx films as an n-type TCO was the conditions O2/Ar = 1.5% during the growth process, at 250 °C, followed by a vacuum post thermal annealing performed at 5 × 10-4 Torr. Our results pointed out clear correlations between the growth conditions, the microstructural and optoelectronic properties, where highly electrically conductive films were found to be associated to larger grains size microstructure. Effects of O2/Ar flow and the thermal annealing process were also analysed and discussed thoroughly.

Proposal of a one-dimensional electron gas in the steps at the LaAlO3-SrTiO3 interface.

The two-dimensional electron gas at the interface between LaAlO(3) and SrTiO(3) has become one of the most fascinating and highly debated oxide systems of recent times. Here we propose that a one-dimensional electron gas can be engineered at the step edges of the LaAlO(3)/SrTiO(3) interface. These predictions are supported by first-principles calculations and electrostatic modeling which elucidate the origin of the one-dimensional electron gas as an electronic reconstruction to compensate a net surface charge in the step edge. The results suggest a novel route to increasing the functional density in these electronic interfaces.

Optimized transport properties of LaAlO3/SrTiO3 heterointerfaces by variation of pulsed laser fluence.

We show the influence of pulsed laser deposition fluence on the transport properties of the LaAlO(3)/SrTiO(3) (LAO/STO) heterointerface. Structural characterization by x-ray diffraction and medium energy ion spectrometry enables us to deduce that the electronic behaviour is extremely sensitive to the stoichiometry of the LAO layer as well as the structural quality of the STO surface. An optimum balance of these two quantities is demonstrated for an intermediate laser fluence.

Magnetic exchange hardening in polycrystalline GdN thin films.

We report the observation of intrinsic exchange hardening in polycrystalline GdN thin films grown at room temperature by magnetron sputtering. We find, in addition to the ferromagnetic phase, that a fraction of GdN crystallizes in a structural polymorphic form which orders antiferromagnetically. The relative fraction of these two phases was controlled by varying the relative abundance of reactive species in the sputtering plasma by means of the sputtering power and N(2) partial pressure. An exchange bias of ∼ 30 Oe was observed at 10 K. The exchange coupling between the ferromagnetic and the antiferromagnetic phases resulted in an order of magnitude enhancement in the coercive field in these films.

Charge confinement and doping at LaAlO3/SrTiO3 interfaces.

The thickness and origin of the free charge layer which forms at the LaAlO_{3}/SrTiO_{3} interface is still uncertain. By inserting Mn dopants at different distances from the interface we can locate the position of carriers within the SrTiO3 surface layers. We show that the majority of the carriers in fully-oxygenated samples are confined within 1 unit cell of the interface. This confirms the "polar-catastrophe" mechanism proposed for this system but the low mobility of these carriers demonstrates the need for improved materials for applications and a more complete understanding of the role of the minority of higher mobility carriers identified.

How to obtain a magnetic hard-soft architecture by pulsed laser deposition.

In spin valve type systems, one ferromagnetic electrode must be magnetically hard to act as a reference layer while the other electrode must be magnetically soft to act as a sensor or storage layer. This magnetic hard-soft architecture can usually be obtained by four different methods: the use of two ferromagnets with different coercive fields (here CoFe(2) and Ni(80)Fe(20)), the use of an underlayer enhancing the coercive field of one of the two ferromagnets (here Ta and Ru), the use of a ferromagnet coupled to a ferrimagnet or antiferromagnet (here NiO/CoFe(2) and CoFe(2)O(4)/CoFe(2)), or the use of an artificial antiferromagnet (here CoFe(2)/Ru/CoFe(2)). We show that at least the first and the third methods seem to work with pulsed laser deposition in the thermodynamic conditions used.

Carotid transposition: another cause of wide retropharyngeal soft tissues.

OBJECTIVE: The purpose of this original report is to describe medial transposition of the common carotid arteries. This transposition may produce wide retropharyngeal soft tissues on lateral cervical radiographs. CONCLUSION: When common carotid arteries are transposed from their normal lateral positions into the retropharyngeal soft tissues, if vascular calcifications are present, this carotid abnormality is easily recognized on plain radiographs. Radiologists and clinical physicians should be aware that vascular transposition may be a benign cause of widening of the retropharyngeal soft tissues.

Aortocoronary saphenous vein graft aneurysm.

An aortocoronary saphenous vein graft aneurysm was diagnosed with computed tomography and selective arteriography in a 79-year-old woman with a history of multiple coronary bypass graft surgeries. Aneurysms of saphenous vein grafts are rare complications of bypass surgery but need to be considered when evaluating bypass patients who present with a mediastinal or paracardiac mass.

Regional patterns of bone loss and altered bone remodeling in response to calcium deprivation in laboratory rabbits.

This study explores the effects of a calcium-deficient diet on patterns of bone remodeling, and examines regional differences in the amount of bone lost. Skeletally mature female rabbits (n = 6) were fed a calcium-deficient diet (0.10% Ca2+ and 0.50% P) for 14 weeks. A separate group of rabbits (n = 4) were fed a maintenance diet (1.2% Ca2+ and 0.45% P). Bone mineral content, serum calcium, and serum phosphorus were measured each week during the experimental period. Following sacrifice, the L3 vertebra, femoral head, proximal tibial metaphysis, and tibial midshaft were analyzed histomorphometrically. Rabbits had 20% less vertebral bone after only 14 weeks of a calcium-deficient diet. As in human postmenopausal osteoporosis, bone loss in calcium-deficient rabbits occurs in the trabecular bone of the lumbar spine before that in the trabecular bone of the lower extremity. Calcium-deficient diets alone do not lead to increased osteoid volume or thickness. Because bone loss is relatively rapid and because the pattern of loss is similar in some respects to that found in humans, adult rabbits may provide an attractive model of calcium deficiency osteoporosis in a skeletally mature mammal in which remodeling is predominant over modeling.

Oral ingestion of narcotic analgesics by rats.

Rats drank solutions of narcotic analgesics as the only drinking fluid available in their cages. Relative to their daily water intake before the drug solutions were introduced, the rats drank more etonitazene solution, less methadone solution, and about the same volume of morphine, meperidine and levorphanol solution as water, although some rats would not drink the higher concentrations of morphine (1.0 mg/ml), levorphanol (1.0 mg/ml) and methadone (1.0 mg/ml). When naloxone (1.0 mg/kg) was administered after 12 days of drinking the drug solutions, the severity of the abstinence syndromes based on scoring of symptoms and on weight loss was morphine greater than or equal to etonitazine greater than levorphanol greater than meperidine greater than methadone. The animals showing the most severe syndrome after naloxone usually consumed more drug solution than usual during the next 24 hours, so that body weights were normal at the end of the 24-hour period. Nonprecipitated abstinence was also studied in these rats by replacing the drug solutions with water 3 to 5 days after the naloxone injection. Rats that had been drinking morphine, etonitazene and levorphanol lost weight for 2 or 3 days and then began to regain their lost weight. In contrast, rats which had been switched from methadone and meperidine solutions to water gained weight rapidly. Morphine and etonitazene drinkers which had been switched to water drank a lesser volume of water than they had been drinking of drug solution whereas some ex-methadone drinkers drank more water.