An extension of the computer program for dynamical calculations of RHEED intensity oscillations. Heterostructures

A practical computing algorithm working in real time has been developed for calculations of the reflection high-energy electron diffraction from the molecular beam epitaxy growing surface. The calculations are based on a dynamical diffraction theory in which the electrons are scattered on a potential, which is periodic in the direction perpendicular to the surface.New version program summaryTitle of program:RHEED_v2Catalogue identifier:ADUY_v1_1Program summary URL:http://cpc.cs.qub.ac.uk/summaries/ADUY_v1_1Program obtainable from: CPC Program Library, Queen's University of Belfast, N. IrelandCatalogue identifier of previous version:ADUYAuthors of the original program:A. DanilukDoes the new version supersede the original program:YesComputer for which the new version is designed and others on which it has been tested: Pentium-based PCOperating systems or monitors under which the new version has been tested: Windows 9x, XP, NT, LinuxProgramming language used:C++Memory required to execute with typical data:more than 1 MBNumber of bits in a word:64 bitsNumber of processors used:1Number of bytes in distributed program, including test data, etc.:1 074 131No. of lines in distributed program, including test data, etc.:3408Distribution format:tar.gzNature of physical problem: Reflection high-energy electron diffraction (RHEED) is a very useful technique for studying the growth and the surface analysis of thin epitaxial structures prepared by the molecular beam epitaxy (MBE). RHEED rocking curves recorded from heteroepitaxial layers are used for the non-destructive evaluation of epilayer thickness and composition with a high degree of accuracy. Rocking curves from such heterostructures are often very complex because the thickness fringes from every layer beat together. Simulations based on dynamical diffraction theory are generally used to interpret the rocking curves of such structures from which very small changes in thickness and composition can be obtained. Rocking curves are also used to determine the level of strain and its relaxation mechanism in a lattice-mismatched system.Method of solution: The new version of the program retains the design and structure of the previous one [A. Daniluk, Comput. Phys. Comm. 166 (2005) 123. [1]].Reasons for the new version: Responding to the user feedback we presented an extension of the RHEED program that enables computing the crystalline potentials for epitaxial heterostructures and corresponding values of the amplitude of the RHEED intensity oscillations.Summary of revisions:(1)In this paper we show how the dynamical approach may be applied to creation of a practical computing algorithm to calculate of the intensity of the specularly reflected RHEED beam during MBE growth of Pb on Si(111). The structural properties of the PbSi interface have beenFig. 1. Contracted division of the substrate and surface layers into an assembly of n atomic layers and i thin slices parallel to the surface.Figure optionsDownload as PowerPoint slide[b]Fig. 2. One-dimensional (z-direction) potential of Pb/Si(111) at 70 K.Figure optionsDownload as PowerPoint slideFig. 3. Computer simulated one-beam rocking curve for some Pb layers on a Si(111) substrate.Figure optionsDownload as PowerPoint slideprs.rt("abs_1st_end");