The use of pulsed laser irradiation in silicon molecular beam epitaxy: A comparative low energy electron diffraction study

Abstract

We present a low energy electron diffraction (LEED) study of the initial stages of epitaxial growth of silicon on silicon with emphasis on the growth mechanisms involved. Silicon is evaporated under ultrahigh vacuum conditions. We used pulsed laser irradiation and thermal annealing for surface preparation and show that epitaxial growth can take place on surfaces, prepared by either procedure. We determined the epitaxial temperature (defined with electron diffraction) for Si(111) and Si(100) substrates. We also used 4.0° vicinal oriented Si(111) to determine the influence of a large number of misorientation steps on the growth mechanism. The (100) epitaxial temperature equals 470 K, much lower than that of Si(111) which is found to be 870 K. The use of vicinal (111) surfaces lowers the epitaxial temperature to 770 K. Pulsed laser irradiation was not only used to prepare clean and ordered substrate surfaces, but also as a means to prepare the metastable Si(111) surface, exhibiting a (1×1) LEED pattern. The initial stages of epitaxial growth on this surface were studied. Room temperature depositions of Si on Si(100) are shown to be partly ordered. Three differently prepared (100) substrates were used to determine the influence of substrate surface preparation on the structure of the overlayer.