Photo-Induced Reversible Modification of II-VI Semiconductor Surface Composition and Structure

1990 ◽  
Vol 201 ◽  
Author(s):  
P. D. Brewer ◽  
J. J. Zinck ◽  
G. L. Olson
Keyword(s):  
Surface Composition ◽  
Removal Rate ◽  
Semiconductor Surface ◽  
Desorption Process ◽  
Composition And Structure ◽  
Thermal Mechanism ◽  
Melting Threshold ◽  
Excimer Laser Irradiation ◽  
Reversible Modification ◽  
Induced Changes

AbstractIt is shown that the composition and structure of CdTe and CdS surfaces can be reversibly controlled by excimer laser irradiation at fluences below the melting threshold. The removal rate is observed to depend exponentially on laser fluence up to the melting threshold. The translational energies of products desorbed from laser-irradiated CdTe surfaces were determined using time-of-flight spectrometry and are well-described by a Maxwellian velocity distribution. The dynamics of the photo-stimulated desorption process are correlated with the laser-induced changes in composition, and it is shown that the data are consistent with a thermal mechanism for desorption. A model is introduced which describes the reversible, fluence-dependent changes in composition and structure in terms of the kinetic competition between formation and desorption processes at the semiconductor surface.

Surface Composition Changes and Ablation Dynamics in Excimer Laser Irradiated CdTe

1990 ◽  
Vol 191 ◽  
Author(s):  
P. D. Brewer ◽  
J. J. Zinck ◽  
G. L. Olson
Keyword(s):  
Laser Ablation ◽  
Excimer Laser ◽  
Surface Composition ◽  
Laser Ablation Process ◽  
Flight Mass Spectrometry ◽  
Rich Condition ◽  
Thermal Mechanism ◽  
Krf Excimer Laser ◽  
Composition Changes ◽  
Cdte Surface

ABSTRACTWe have investigated the dynamics of KrF excimer laser ablation of CdTe and the fluence dependent changes in surface stoichiometry that accompany the laser ablation process. The composition of the CdTe surface was reversibly controlled between stoichiometric and a Te-rich condition by varying the laser fluence over the range from 15–65 mJ/cm2. The primary species ejected from the irradiated surface were Cd atoms and Te2 molecules. Their velocity distributions as measured by time-of-flight mass spectrometry were found to be Maxwellian. From the analysis of the velocity distributions, the preferential desorption of surface atoms, and the reversible nature of the process, we conclude that the desorption is due to a photo-thermal mechanism which mediates the competition between Te2 formation and desorption and the desorption of Cd atoms.

scholarly journals Dyes Adsorption Behavior of Fe3O4 Nanoparticles Functionalized Polyoxometalate Hybrid

Molecules ◽  
2019 ◽  
Vol 24 (17) ◽  
pp. 3128 ◽  
Author(s):  
Jie Li ◽  
Chen Si ◽  
Haiyan Zhao ◽  
Qingxi Meng ◽  
Bowen Chang ◽  
...  
Keyword(s):  
Adsorption Kinetics ◽  
Removal Rate ◽  
Aqueous System ◽  
Blocking Temperature ◽  
Isotherm Models ◽  
Zero Field ◽  
Magnetic Adsorbent ◽  
Anionic Dyes ◽  
Desorption Process ◽  
Dyes Adsorption

The magnetic adsorbent, Fe3O4@[Ni(HL)2]2H2[P2Mo5O23]·2H2O (Fe3O4@1), is synthesized by employing the nanoparticles Fe3O4 and polyoxometalate hybrid 1. Zero-field-cooled (ZFC) and field-cooled (FC) curves show that the blocking temperature of Fe3O4@1 was at 120 K. Studies of Fe3O4@1 removing cationic and anionic dyes from water have been explored. The characterization of Fe3O4@1, effects of critical factors such as dosage, the concentration of methylene blue (MB), pH, adsorption kinetics, isotherm, the removal selectivity of substrate and the reusability of Fe3O4@1 were assessed. The magnetic adsorbent displayed an outstanding removal activity for the cationic dye at a broad range of pH. The adsorption kinetics and isotherm models revealed that the adsorption process of Fe3O4@1 was mainly governed via chemisorption. The maximum capacity of Fe3O4@1 adsorbing substance was 41.91 mg g−1. Furthermore, Fe3O4@1 showed its high stability by remaining for seven runs of the adsorption-desorption process with an effective MB removal rate, and could also be developed as a valuable adsorbent for dyes elimination from aqueous system.

Surface composition and structure of nickel ultra-thin films deposited on Pd(111)

2007 ◽  
Vol 156-158 ◽  
pp. 405-408 ◽  
Author(s):  
M.F. Carazzolle ◽  
S.S. Maluf ◽  
A. de Siervo ◽  
P.A.P. Nascente ◽  
R. Landers ◽  
...  
Keyword(s):  
Thin Films ◽  
Surface Composition ◽  
Composition And Structure
Sign in / Sign up

Export Citation Format

Share Document