scholarly journals Tuning Up or Down the Critical Thickness in LaAlO3 /SrTiO3 through In Situ Deposition of Metal Overlayers

2017 ◽  
Vol 29 (28) ◽  
pp. 1700486 ◽  
Author(s):  
Diogo Castro Vaz ◽  
Edouard Lesne ◽  
Anke Sander ◽  
Hiroshi Naganuma ◽  
Eric Jacquet ◽  
...  
Author(s):  
Sheila Shahidi ◽  
Sanaz Dalalsharifi ◽  
Mahmood Ghoranneviss ◽  
Rattanaphol Mongkholrattanasit

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Lucas C. R. Silva ◽  
Rodrigo Studart Corrêa ◽  
Jamie L. Wright ◽  
Barbara Bomfim ◽  
Lauren Hendricks ◽  
...  

AbstractAmazonian Dark Earths (ADEs) are unusually fertile soils characterised by elevated concentrations of microscopic charcoal particles, which confer their distinctive colouration. Frequent occurrences of pre-Columbian artefacts at ADE sites led to their ubiquitous classification as Anthrosols (soils of anthropic origin). However, it remains unclear how indigenous peoples created areas of high fertility in one of the most nutrient-impoverished environments on Earth. Here, we report new data from a well-studied ADE site in the Brazilian Amazon, which compel us to reconsider its anthropic origin. The amounts of phosphorus and calcium—two of the least abundant macronutrients in the region—are orders of magnitude higher in ADE profiles than in the surrounding soil. The elevated levels of phosphorus and calcium, which are often interpreted as evidence of human activity at other sites, correlate spatially with trace elements that indicate exogenous mineral sources rather than in situ deposition. Stable isotope ratios of neodymium, strontium, and radiocarbon activity of microcharcoal particles also indicate exogenous inputs from alluvial deposition of carbon and mineral elements to ADE profiles,  beginning several thousands of years before the earliest evidence of soil management for plant cultivation in the region. Our data suggest that indigenous peoples harnessed natural processes of landscape formation, which led to the unique properties of ADEs, but were not responsible for their genesis. If corroborated elsewhere, this hypothesis would transform our understanding of human influence in Amazonia, opening new frontiers for the sustainable use of tropical landscapes going forward.


1998 ◽  
Vol 533 ◽  
Author(s):  
O. Leifeld ◽  
D. Grützmacher ◽  
B. Müller ◽  
K. Kern

AbstractThe morphology of Si(001) after carbon deposition of 0.05 to 0.11 monolayers (ML) was investigated in situ by ultrahigh vacuum scanning tunneling microscopy (UHV-STM). The carbon induces a c(4×4)-reconstruction of the surface. In addition, carbon increases the surface roughness compared to clean Si(001) (2×1). In a second step, the influence of the carbon induced restructuring on Ge-island nucleation was investigated. The 3D-growth sets in at considerably lower Ge coverage compared to the clean Si(001) (2×1) surface. This leads to a high density of small though irregularly shaped dots, consisting of stepped terraces, already at 2.5 ML Ge. Increasing the Ge-coverage beyond the critical thickness for facet formation, the dots show { 105 }- facets well known from Ge-clusters on bare Si(001) (2×1). However, they are flat on top with a (001)-facet showing the typical buckled Ge rows and missing dimers. This indicates that the compressive strain is not fully relaxed in these hut clusters.


1998 ◽  
Vol 299 (1-2) ◽  
pp. 15-22 ◽  
Author(s):  
A Canesi ◽  
M.R Cimberle ◽  
C Ferdeghini ◽  
A Diaspro ◽  
P Guasconi ◽  
...  

1989 ◽  
Vol 146 ◽  
Author(s):  
Paihung Pan ◽  
Ahmad Kermani ◽  
Wayne Berry ◽  
Jimmy Liao

ABSTRACTElectrical properties of thin (12 nm) SiO2 films with and without in-situ deposited poly Si electrodes have been studied. Thin SiO2 films were grown by the rapid thermal oxidation (RTO) process and the poly Si films were deposited by the rapid thermal chemical vapor deposition (RTCVD) technique at 675°C and 800°C. Good electrical properties were observed for SiO2 films with thin in-situ poly Si deposition; the flatband voltage was ∼ -0.86 V, the interface state density was < 2 × 1010/cm2/eV, and breakdown strength was > 10 MV/cm. The properties of RTCVD poly Si were also studied. The grain size was 10-60 rim before anneal and was 50-120 rim after anneal. Voids were found in thin (< 70 nm) RTCVD poly Si films. No difference in either SiO2 properties or poly Si properties was observed for poly Si films deposited at different temperatures.


1993 ◽  
Vol 1 (3-6) ◽  
pp. 815-826 ◽  
Author(s):  
J.Y. Juang ◽  
K.H. Wu ◽  
T.C. Lai ◽  
M.H. Lee ◽  
M.C. Hseih ◽  
...  

2021 ◽  
Vol 191 ◽  
pp. 600-607
Author(s):  
Xinglu Zhou ◽  
Anlin Yin ◽  
Junlu Sheng ◽  
Jiayan Wang ◽  
Huifen Chen ◽  
...  

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