Atomic scale investigation of clean and epi-grown Si(001) surfaces using scanning tunneling microscopy

Abstract

III ( liis lİK'.sis, cl('aii and <‘|)i-grovvn Si(üü 1 )(2 x I) suriacc's ai(' aııalysc'd by Scanning 'I'nnnc'ling Micioscopy (S'l'M). 'I'lu' S'l'lM and IMlra High Vacuum SysicMii (UH V) in which thc' microscope is installed, are dc'scrihed. A brief history of the studic's on the' rc'coristruction and ruudamental leaturc's of the Si(OOl) surface is also given, f'irst, the sample and tip |)rc'paration technicpies were optimized. Sample prc'paration method, which inclndc;s both e.v situ chemical and in situ heating clc'aning procedures, was found not to give routinely the clc'an and atomically flat surfaces, because of the criticality of the' temperature values used during heat treatments. The monoatomic steps, dimcM' rows, delects such as missing dimer and dimer groups, were observed on clc'aii Si(OOl) surfaces. Double height step formation due to contamination was also detc'cted on a few sa.m|)l('s. Buckling of dimers which is bcdievcxl to bc' due mainly to either the high dc'fect density or tip-surface interaction, was observeebon one sample. Si and Ce were grown epita.xially on the silicon substrate, with 0.1 I ML and 0.2 ML coverages, respectively. 'Flie Si growth on Si(OOl) was found to occur as island lomiation because of the low substrate teruperature (~ .’lOO °('). Strong shape anisotropy and diilusional anistropy in the grovvtii have been observed. On tlie otiu'r hand, th(‘ large coverage of Ce on Si(OOl) at a relativ('ly high substrate t('m|)('ra.tui(' ( ~ hOO °('), ar(' r('sult('d in step How growth ratlu'r than individual island rormatioii on the t('irac('s.