Direct Determination of 3D Distribution of Elemental Composition in Single Semiconductor Nanoislands by Scanning Auger Microscopy.

Semyon S Ponomaryov,Mykhailo Ya Valakh,Peter M Lytvyn,Volodymyr O Yukhymchuk

doi:10.1186/s11671-016-1308-x

Abstract

An application of scanning Auger microscopy with ion etching technique and effective compensation of thermal drift of the surface analyzed area is proposed for direct local study of composition distribution in the bulk of single nanoislands. For GexSi1 − x-nanoislands obtained by MBE of Ge on Si-substrate gigantic interdiffusion mixing takes place both in the open and capped nanostructures. Lateral distributions of the elemental composition as well as concentration-depth profiles were recorded. 3D distribution of the elemental composition in the d-cluster bulk was obtained using the interpolation approach by lateral composition distributions in its several cross sections and concentration-depth profile. It was shown that there is a germanium core in the nanoislands of both nanostructure types, which even penetrates the substrate. In studied nanostructures maximal Ge content in the nanoislands may reach about 40 at.%.

Highlights

Quantum dots (QDs) and other nanoobjects, where electrons are subjected to dimensional confinement, attract considerable interest of researchers and technologists because of their anticipated application in optoelectronics and quantum informatics [1,2,3,4,5]
Ge and Si Lateral Distribution in Single Nanoislands To start with, let us consider the problem on obtaining image of the surface area containing GeSi QDs by the scanning Auger electron microscopy
Since lateral size of the studied structures is in the range of 30 to 70 nm, mapping should be performed at high magnification and high resolution in Auger and secondary electron image modes, which requires overcoming a number of difficulties

Summary

Introduction

Quantum dots (QDs) and other nanoobjects, where electrons are subjected to dimensional confinement, attract considerable interest of researchers and technologists because of their anticipated application in optoelectronics and quantum informatics [1,2,3,4,5]. Selfinduced growth by heteroepitaxy under StranskyKrastanov growth mode is one of the most attractive ways of creating such objects due to a number of technological reasons [10] This way allows producing huge homogeneous arrays of QDs relatively easy and fast [11, 12]. In this case, nanoislands are formed on the growing film because it accumulates high mechanical stresses due to lattice mismatch between film and the film in the process of its growth changes its morphology, but in general case its composition [16]. Diffusion may be ignored under these conditions for the whole film-substrate system, but it should be considered in the nanosize system areas

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