Nanoscale changes in the morphology and elemental composition of cleavage surfaces of gallium arsenide crystals, which arise due to thermally stimulated surface autosegregation, are investigated in detail and systematized. It is shown that, depending on the annealing conditions (temperature, duration, and evacuation), gallium arsenide dissociates, forming submicron nonstoichiometric layers on the surface or local phases of arsenic, gallium, and gallium oxide. The mechanism and nature of autosegregation are determined by the competing processes of arsenic sublimation and its surface diffusion with an activation energy of ∼31 kJ/mol. The migration of arsenic atoms is described with the help of a crystallochemical model. The nanomorphology of the surface phases includes arsenic and gallium nanoparticles with sizes of 10-200 nm, their agglomerates, and gallium oxide nano- and microcrystallites combined in plate- and chainlike configurations.

Nanoscale peculiarities of the thermally stimulated surface autosegregation of covalent crystals: Gallium arsenide

An electron-spectroscopic analysis is made of layered nanostructures and clusters at the surface and in the bulk of a solid. A new method of forming metal/insulator/semiconductor (superconductor) nanostructures is proposed based on ion-stimulated metal segregation effects at the surface of low-temperature gallium arsenide and a 123 high-temperature superconductor. The geometric parameters and electronic structure of these nano-objects are studied. It is shown that their electronic properties can be controllably varied in situ by acting on the surface. The dimensional transformation of the electronic properties of metal clusters is studied for clusters in the insulator SiO2, in the superconductor LTMBE-GaAs, and on silicon and graphite surfaces. The nature of this transformation is clarified. A diagnostics for cluster ensembles is developed by which one can determine the parameters needed to describe singleelectron transport: the average number of atoms per cluster, the average distance between clusters and isolated atoms, and the chemical state of the atoms. Ensembles of silver clusters with specified parameters are obtained on a silicon surface. It is shown that these ensembles are potentially useful for developing single-electron devices.

V. M. Mikushkin

Papers

Electron spectroscopy of objects for nanoelectronics