Atomic Force Microscopy and EDX Analysis for Investigation Photoconductive LT-GaAs Terahertz Antennas

2018 ◽  
Vol 271 ◽  
pp. 92-97
Author(s):  
Sergey Nomoev ◽  
Ivan Vasilevskii ◽  
Erzhena Khartaeva

We investigate the influence of the surface properties of a low-temperature-grown GaAs photoconductive antenna on the terahertz (THz) response power. A comparison to the surface roughness which is extracted from an atomic force microscope is given. We used energy dispersive x-ray spectroscopy (EDX) measurements to determine the Ga/As compositional ratio in the LT-GaAs.

2006 ◽  
Author(s):  
M. L. Zanaveskin ◽  
Yu. V. Grishchenko ◽  
A. L. Tolstikhina ◽  
V. E. Asadchikov ◽  
B. S. Roshchin ◽  
...  

2020 ◽  
Vol 44 (6) ◽  
pp. 451-458
Author(s):  
Ki-Ho Park ◽  
Se Jik Han ◽  
Samjin Choi ◽  
Kyung Sook Kim ◽  
Steven Park ◽  
...  

Objective: The surface roughness of various orthodontic materials could affect biofilm formation and friction. The purpose of this study was to examine the surface roughness and chemical composition of the slots and wings of several ceramic self-ligating brackets. Study design: Four types of ceramic self-ligating brackets were separated into experimental groups (DC, EC, IC, and QK) while a metal self-ligating bracket (EM) was used as the control group. Atomic force microscopy and energy-dispersive x-ray spectroscope were used to examine the surface roughness and chemical composition of each bracket slot and wing. Results: The control group was made of ferrum and chrome while all the experimental groups were comprised of aluminum and oxide. There was a statistically significant difference in the roughness average (Sa) among the various self-ligating brackets (p< 0.001 in slots and p<0.01 in the wing). The slots in the EC group had the lowest Sa, followed by the DC, IC, control, and QK groups. The wings in the IC group had the lowest Sa, followed by the EC, DC, control, and QK groups. Conclusions: There is a significant difference in the surface roughness of the slots and wings among several types of ceramic self-ligating brackets.


2010 ◽  
Vol 159 ◽  
pp. 101-104
Author(s):  
Emil Manolov ◽  
Mario Curiel ◽  
Nicola Nedev ◽  
Diana Nesheva ◽  
Juan Terrazas ◽  
...  

Thin SiOx films deposited by reactive r.f. magnetron sputtering of Si at partial pressure ratios R between oxygen and argon in the range 15%-0.03% are studied. X-ray photoelectron spectroscopy and Variable angle spectroscopic ellipsometry prove enrichment with Si of the layers deposited at R < 0.5 %. Ellipsometric data give information about the refractive index and extinction coefficient of the films. Atomic Force Microscopy results show that for all samples high temperature annealing at 1000oC leads to a decrease of the surface roughness.


1994 ◽  
Vol 340 ◽  
Author(s):  
G. Padeletti ◽  
G. M. Ingo ◽  
P. Imperatori

ABSTRACTGa0.65In0.35As layers of a varying nominal epilayer thickness (10 – 1000 nm) have been grown by the MBE technique on GaAs (100) substrates and characterized by the combined use of atomic force microscopy (AFM) and grazing incidence X-ray diffraction (GIXD). The surface roughness and morphology have been investigated. The GIXD and AFM results show that the thinnest films are characterized by an asymmetric strain relaxation along the two <110> directions with no surface crosshatched pattern but with a misfit dislocation network. AFM images on the thickest films show also well-oriented protrusions along the [110] direction, which increase in size and become more elongated as the nominal film thickness increases.


Technologies ◽  
2021 ◽  
Vol 9 (2) ◽  
pp. 36
Author(s):  
Ibrahim Cisse ◽  
Sarah Oakes ◽  
Shreen Sachdev ◽  
Marc Toro ◽  
Shin Lutondo ◽  
...  

Polyethersulfone (PES) films are widely employed in the construction of membranes where there is a desire to make the surface more hydrophilic. Therefore, UV photo-oxidation was studied in order to oxidize the surface of PES and increase hydrophilicity. UV photo-oxidation using low pressure mercury lamps emitting both 253.7 and 184.9 nm radiation were compared with only 253.7 nm photons. The modified surfaces were characterized using X-ray photoelectron spectroscopy (XPS), atomic force microscopy (AFM), and water contact angle (WCA) measurements. Both sets of lamps gave similar results, showing an increase of the oxygen concentration up to a saturation level of ca. 29 at.% and a decrease in the WCA, i.e., an increase in hydrophilicity, down to ca. 40°. XPS detected a decrease of sp2 C-C aromatic group bonding and an increase in the formation of C-O, C=O, O=C-O, O=C-OH, O-(C=O)-O, and sulphonate and sulphate moieties. Since little change in surface roughness was observed by AFM, the oxidation of the surface caused the increase in hydrophilicity.


2008 ◽  
Vol 368-372 ◽  
pp. 1483-1485 ◽  
Author(s):  
Rui Hai Cui ◽  
Zhao Hua Jiang ◽  
Zhong Ping Yao

With the approach of anodic oxidation, TiO2/Ti film doped with Cu2+ was produced in H2SO4 electrolyte mixed with CuSO4. The surface morphology and the roughness of the films were studied with atomic force microscopy. The phase composition of the films was studied by X-ray diffraction. The photocatalytic activity of the films was compared through the photocatalytic degradation rate of phenol. The relations of the photocatalytic activity to the concentration of Cu2+, the microstructure and the surface roughness of the film were investigated. The results showed that Cu2+ increased the surface roughness and restrained the growth of crystal. In addition, the phenol in aqueous solution was successfully photodegraded under visible light irradiation by Cu2+-TiO2/Ti film. The composition and structure of the film affected the catalytic activity greatly. Compared with TiO2/Ti film, the recombination rate of e- and h+ of Cu2+-TiO2/Ti film was decreased.


1998 ◽  
Vol 512 ◽  
Author(s):  
T. J. Kropewnicki ◽  
P. A. Kohl

ABSTRACTThe use of purified hydrazine cyanurate as a solid source of hydrazine in the low temperature nitridation of GaAs (100) and (111) and sapphire (0001) is demonstrated. Thenitridated surfaces were analyzed by X-ray Photoelectron Spectroscopy (XPS) for chemical composition and Atomic Force Microscopy for surface morphology. The GaAs surfaces were composed primarily of GaN, GaAs, and Ga2O3, and were as smooth as unprocessed standards. The nitridated sapphire surfaces were composed of A1NxO1-x and exhibited three-dimensional growth for long nitridation times.


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