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.

Room-temperature growth of submonolayers of silicon on Si(001) studied with scanning tunneling microscopy

“…The room temperature growth of silicon on Si͑001͒ has been studied with a number of techniques such as TEM, 2 Rutherford backscattering/channeling, 3,4 and low-energy electron diffraction. [5][6][7] These results led to some controversy as to whether the first layers of silicon on Si͑001͒ grow epitaxially at room temperature or not.…”

Surface roughening by electron beam heating

“…To clean the surface, several techniques are used based on wet chemical etching, ion sputtering, and thermal annealing. Direct thermal radiation, 3,4 passing current through the sample, 5,6 laser annealing, 7,8 galliation, 9 electron-cyclotron-resonance ͑ECR͒ assisted hydrogen plasma, 10,11 and direct electron beam annealing [12][13][14][15] are only a few of the many thermal techniques currently available. Direct electron beam annealing has an advantage over direct thermal radiation and conventional electrical heating of providing rapid temperature control and lower levels of outgassing.…”

STM study of the effects of pulsed laser irradiation on semiconductor surfaces

“…A quick process is the irradiation of a specimen surface with a high-power pulsed laser beam by heating a localized near-surface region for a few microseconds to nanoseconds (Zehner et al, 1980). Although the results of low energy electron diffraction (LEED) and Auger electron spectroscopy (AES) studies indicate that irradiated surfaces are atomically clean and well-ordered, exhibiting the (1 x 1) and (7x7) patterns of Si(ll1) (Zehner etal., 1980(Zehner etal., ,1981de Jong et al, 1983), the observation of a laser irradiated Si surface with a scanning tunnelling microscope (STM) (Binnig et al, 1982) showed the surface ripples with periodicities close to lpm (Heil et al, 1988). Then a question arises: can the rippled surface exhibit the ordered LEED patterns?…”