Clustering and layering of In adatoms on low and high index silicon surfaces: A comparative study

Abstract

Using the morphological differences of low and high index surfaces as templates for metal growth, several low dimensional overlayer structures with novel structural and electronic properties can be formed. We present here a first report on submonolayer adsorption and residual thermal desorption studies of In adatoms on reconstructed high index Si (55 12)-2x1 surface and compare it with the observations on planar Si (111) -7 x 7 surface. The study is done by using in-situ Ultra High Vacuum surface sensitive probes like Auger Electron Spectroscopy (AES) and Low Energy Electron Diffraction (LEED). These conventional wide area techniques provide an understanding of atomistic issues involved in the evolution of the interface. We have observed an anomalous growth mode during adsorption at room temperature (RT) above 2ML, which includes adatom layering and clustering on Si (111) surface. This is also manifested during the desorption experiments on both surfaces, and the subtle differences on the two surfaces are discussed. The observation of LEED pattern during the adsorption process shows formation of different superstructural phases on Si (111 )-7 x 7 surface. On Si (5512) 2 x 1 surface we observe the sequential2x (225), 2x (337) and 2x (113) facet formation during adsorption/desorption, which include quasi 1D-nanowire/chain structures. A combination of lattice strain effects, presence of step-edge barrier and quantum size effects are employed to speculate the differences in adsorption and desorption.

InAs nanowire growth on oxide-masked 〈111〉 silicon

“…It is known that at roughly 520 1C indium begins desorption from the /111S Si surface and increases rapidly with increasing temperature such that by 550 1C no indium can be detected [19]. This agrees well with our observation that above 525 1C nucleation yield drops and stops completely above 540 1C.…”

Growth kinetics of indium metal atoms on Si(1 1 2) surface

“…With increase in the temperature, the lattice mismatch between In and Si(11 2) decreases gradually and temperature induced gradual reduction in strain of In/Si(11 2) system forms pseudomorphic flat layer . In the previous studies, a similar temperature induced clustering to layering phenomena of indium atoms has been reported on high index Si surfaces such as Si(11 3) (250-350 C) [3], trenched Si(5 51 2)-2 Â 1 (400-550 C) [28,30] and triple atomic stepped Si (5 5 7)-7 Â 1 (250-340 C) surface [29]. On annealing the In/Si (11 2) surface beyond 520 C, a fall in the indium coverage was observed till 600 C which signifies the desorption of indium bilayer.…”

“…On further deposition, a continuous linear increment in the I In/Si ratio is observed which suggest that In growth on Si(11 2) surface follows layer-by-layer or Frank-van der Merve (FM) growth mode. Recent reports of growth kinetics of In on Si also shows FM growth mode for Si (11 3) and Si (5 5 7), whereas Si (5 5 3), Si(5 51 2) and Si(111) were found to follow Stranski-Krastanov growth mode after 2 ML deposition [3,[28][29][30][31].…”

Growth mechanisms and process window for InAs V-shaped nanoscale membranes on Si[001]

“…For growth temperatures above 520 • C the tips become rounded, the arms assume again a rectangular shape and the interface height is further reduced. This shape evolution can be understood in terms of a temperature-activated group III adatom desorption mechanism; recent reports show that indium desorption from a (111) Si surface and from a pattern containing InAs nanowires becomes relevant at substrate temperatures between 520 and 570 • C [45]. At 540 • C, the nucleation yield drops since most of the In adatoms and InAs are desorbed.…”