SIMULATION OF MIRROR ELECTRON MICROSCOPY CAUSTIC IMAGES IN THREE-DIMENSIONS

S M Kennedy,C X Zheng,D E Jesson

doi:10.1142/s0218625x19500136

Abstract

A full, three-dimensional (3D) ray tracing approach is developed to simulate the caustics visible in mirror electron microscopy (MEM). The method reproduces MEM image contrast resulting from 3D surface relief. To illustrate the potential of the simulation methods, we study the evolution of crater contrast associated with a movie of GaAs structures generated by the droplet epitaxy technique. Specifically, we simulate the image contrast resulting from both a precursor stage and the final crater morphology which is consistent with an inverted pyramid consisting of (111) facet walls. The method therefore facilities the study of how self-assembled quantum structures evolve with time and, in particular, the development of anisotropic features including faceting.

Highlights

Mirror electron microscopy (MEM) is a well-established technique which has a number of advantages for the study of nanostructure formation.[1,2,3,4,5,6,7,8] Electrons neither impact nor are emitted from the specimen surface
To illustrate the potential of the simulation methods, we study crater contrast associated with GaAs structures generated by the droplet epitaxy technique.[29,30,31,32,33,34,35,36]
The ability to perform full 3D simulations of MEM contrast opens up the possibility of studying the realtime evolution of faceting and growth anisotropy during nanostructure fabrication

Summary

Introduction

Mirror electron microscopy (MEM) is a well-established technique which has a number of advantages for the study of nanostructure formation.[1,2,3,4,5,6,7,8] Electrons neither impact nor are emitted from the specimen surface. The re°ected electrons in MEM indirectly contain information related to the topography and/or the electrical and magnetic properties of the surface This has stimulated signicant e®orts to interpret MEM image contrast and extract quantitative information regarding the surface properties.[1,2,6,8,13,14,15,16,17,18,19,20,21,22,23,24] In general, MEM image contrast can be highly non-intuitive since it arises from electriceld variations above the specimen. To illustrate the potential of the simulation methods, we study crater contrast associated with GaAs structures generated by the droplet epitaxy technique.[29,30,31,32,33,34,35,36]

MEM Imaging Geometry

Conclusions