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Low energy ion beam-induced modification of InSb surface studied at nanometric scale

Krok F., Kołodziej J.J., Such B., Piątkowski P., Szymoński M., Odendaal R.Q., Malherbe J.B.

Optica Applicata

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2002

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Vol. 32, nr 3

221-226

EN

Atomically flat InSb(001) surface has been prepared with cycles of sputter-cleaning and annealing. The surface structure has been characterized by low energy electron diffraction (LEED) and by atomic force microscopy (AFM). Then the surface has been bombarded with 4 keV Ar+ ions incident 50° off normal, and the morphological changes have been studied with the AFM as a function of the ion dose. It was found that the surface was amorphized already for low ion doses (~2×1015/cm2). At higher ion doses (of 2×1016/cm2) the surface appeared to be covered with the system of parallel nanowires running along surface projection of the ion beam direction. Typical sizes of the nanowires were: 1.5–2 mm length, 50–70 nm width and height 5–7 nm.

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Modyfikacja powierzchni w procesie elektronowo symulowanej desorpcji

Such B., Kołodziej J., Krok F., Meisel K., Czuba P., Piątkowski P., Struski P., Szymoński M.

Elektronika : konstrukcje, technologie, zastosowania

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2001

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Vol. 42, nr 8-9

48-50

EN

Alkali halide surface modification due to electron irradiation was investigated with the use of dynamic force microscopy (DFM) and quadrupole mass spectroscopy (QMS). As a result of desorption of atoms from the surface, rectangular pits are created in the topmost layer of the crystal. During irradiation the pits are growing and linking with others what leads to layer-by-layer desorption. Desorption yields of both components exhibit oscillatory dependence on the dose of impinging electrons. Moreover, a correlation has been found between the number of low-coordinated sites on the surface and desorption efficiency. The model is proposed, in which the phenomenon is explained by creation of dynamic equilibrium between competitive processes: (i) desorption and recombination of pairs of defects and (ii) accumulation of F centres in proximity of the surface, which is directed by the topography of the surface.

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Nanoscale studies of electron-stimulated desorption of alkali halides

Szymoński M., Kołodziej J., Struski P., Such B., Czuba P., Piątkowski P.

Electron Technology

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2000

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Vol. 33, No. 3

369-374

EN

Electron-stimulated desorption processes of alkali halides have been studied with nanoscale resolution techniques allowing for microscopic understanding of ejection and surface modification mechanisms in those materials. Over the two recenty years, new experimental data were obtained for NaCl, KCl, and KBr nanometer thin films epitaxially grown on GaAs (001) and InSb (001) substrates. Well characterized surfaces were desorbed with 1 keV electrons of various dose and current density. The ejected species were analysed with a mass selected time-of flight spectrometer. We have measured the absolute yields for both alkali and halogen atom components of desorption as well as their translational velocity distributions as a function of the film thickness in the range from 1 to 100 nm. It was found that both the fast and the slow (thermal) components of desorption were strongly thickness dependent due to diffusion mechanisms involved in the transport of the primary excitation products from the bulk to the surface. Topographic features of the modified bulk single crystals of KCl (001) and KBr (001) were observed with an UHV non-contact atomic force microscope (NC-AMF). Rectangular holes of monolayer depth with edges oriented along the main crystallographic directions of the (001) plain were visible on the irradiated surfaces. We found that ESD of alkali halides studied in this work essentially occurred in layer-by-layer mode, except for the fact that the erosion of the consecutive layer started before the erosion of the previous one was completed. The average desortion rates were determined quantitatively from our microscopic data and they were compared with the ones obtained from thin film experiments.