Anton S. Kozhukhov

Inertness and degradation of (0001) surface of Bi2Se3 topological insulator

Inertness of the cleaved (0001) surface of the Bi2Se3 single crystal, grown by modified Bridgman method, to oxidation has been demonstrated by X-ray photoelectron spectroscopy, scanning tunneling microscopy, and by ab initio DFT calculations. No intrinsic bismuth and selenium oxides are formed on the low-defect, atomically flat Bi2Se3(0001)-(1×1) surface after a long-time air exposure. The inertness of Bi2Se3(0001) to O2 and NO2, as well as bismuth-oxygen bonding formation under molecular adsorption in the Se vacancy was supported by DFT calculations.

Defects in GaSe grown by Bridgman method

Optical quality GaSe crystals have been grown by vertical Bridgman method. The structural properties and micromorphology of a cleaved GaSe(001) surface have been evaluated by RHEED, SEM and AFM. The cleaved GaSe(001) is atomically flat with as low roughness as ∼0.06 nm excepting local hillock type defects. The hillock‐type formations are round‐shaped with a bottom diameter of ∼200 nm and a height of ∼20–35 nm. The drastic depletion of the hillock material by gallium has been indicated by EDX measurements.

AFM tip-induced modification of semiconductor surface properties

The method to change surface potential by atomic force microscope (AFM) probe is demonstrated and used. The possibilities of two dimensional electron gas reversible modulations are demonstrated on the example of nanoscale local AFM tip-induced surface nanomodification of heteroepitaxial AlGaAs/GaAs. The surface potential modulation is shown to be 100 mV with sample resistance change being 20-40 KOhm. Surface potential change is detected by Kelvin Scanning Probe Microscopy (KSPM).

Nanointervention into crystal flatland. III. Crystal growth and micromorphology of cleaved GaSe(001) surface

Optical quality GaSe crystals with diameter of 10 mm have been grown by modified Bridgman method using unusual oscillating temperature regime in the middle zone at the level of crystallization front. Cleaved surface (001) has been evaluated by SEM and AFM. Basic cleaved surface with area up to ~200 mm2 is flat with as low rms parameter as 0,3 nm. Such local defects as hillocks up to 35 nm and mesostructure are observed by SEM and AFM.

Formation of DNA molecules ordered systems on silicon surfaces

Currently, the rapidly developing nanotechnology unite different fields of science such as biology, chemistry and physics. Particular attention is paid to the problem of the controlled arrangement of DNA molecules on solid surfaces. Properties of atomically smooth surface of silicon are change by the method of creating local charged regions. The ordering of DNA molecules on the anodic Si surface under the influence of an external field is demonstrated.

Stability of (0001) Bi 2 Te 3 surface

The surface stability of single crystals Bi<inf>2</inf>Se<inf>3</inf> and Bi<inf>2</inf>Te<inf>3</inf> has been studied by XPS, AFM, STM and RHEED techniques. The Bi<inf>2</inf>Se<inf>3</inf> and Bi<inf>2</inf>Te<inf>3</inf> single crystals were grown by vertical Bridgman method. Crystal cleaving induced atomically flat surfaces over 1 cm² area. XPS revealed that cleaved Bi<inf>2</inf>Se<inf>3</inf> and Bi<inf>2</inf>Te<inf>3</inf> surface were stable to oxidation over two months. The surfaces are sufficiently inert to obtain STM atomic resolution even in two weeks after cleaved.

AFM study of atomic-flat terraces on ZnWO 4 (010) cleaved surface

Atomic force microscopy (AFM) is a useful instrument to explore the top-surface properties. The nano-morphology of ZnWO4 (010) cleaved surface has been evaluated in the present study. Optical-quality ZnWO4 crystal has been grown by the Low Thermal Gradient Czochralski technique. An atomically smooth surface can be obtained by mechanical cleaving under ambient atmospheric conditions due to high cleavage of ZnWO4 crystal parallel the (010). Atomic steps with height of 0.57 nm were observed by AFM measurements. The steps contain mesodefect peaks with height of ∼1 nm located uniformly on the cleaved surface.

Clustering of CdS nanocrystals during evaporation of Langmuir — Blodgett matrix

Clustering of CdS nanocrystals during evaporation of the Langmure—Blodgett matrix and influence of matrix thickness on the parameters of the resulting clusters have been investigated. Information about the size and spatial distribution of nanocrystals and clusters has been obtained using atomic-force microscopy. It has been found that at thickness of the matrix less than 6 nm the free-standing nanocrystals are formed; with increase in thickness of the matrix nanocrystals are collected in clusters. The clusters greatly enlarge with further increase in thickness of the matrix, eventually; at thickness of 60 nm nanocrystals totally coat the substrate.