Pure Appl. Chem., Vol. 74, No. 9, pp. 1651–1661, 2002. © 2002 IUPAC 1651 Formation of interfacial phases in the epitaxial growth of Sb on Si(111)-7 × 7 reconstructed surface* Vinod Kumar Paliwal 1,2 , A. G. Vedeshwar 2 , and S. M. Shivaprasad 1,‡ 1 Surface Physics Group, National Physical Laboratory, New Delhi 110 012, India; 2 Department of Physics and Astrophysics, University of Delhi, Delhi 110 007, India Abstract: Understanding the evolution of the Sb/Si(111) interface is of great interest in the formation of devices of nanodimensions. We have undertaken in situ (~10 –11 torr) studies of Sb adsorption (at room temperature) and its desorption on the 7 × 7 reconstructed Si(111) surface, by complementary techniques such as X-ray photoelectron spectroscopy (XPS), Auger electron spectroscopy (AES), low-energy electron diffraction (LEED), and electron energy loss spectroscopy (EELS). For room-temperature (RT) Sb adsorption, the overlayer grows in the Frank van der Merwe mode, forming an interface state of δ(7 × 7) in the sub- monolayer Sb coverage regime. Adsorption of 1.0 monolayer (ML) Sb at RT shows an abrupt shift of 0.8 eV in the peak position of the Sb 3d 5/2 transition owing to band-bending caused by a metallic (7 × 7) to a semiconducting (1 × 1) surface phase transformation. Changes observed in full width at half-maximum (fwhm) and Sb 3d 3/2 and 3d 5/2 branching ratio are discussed. Thermal annealing experiments provide evidence for agglomeration of Sb islands, before the multilayer and monolayer desorption. During this desorption process, we have observed two novel surface phases of (5 × 5) at 0.4 ML and (5√3 × 5√3 – R30°) at 0.2 ML, stable at higher temperatures. INTRODUCTION Formation of compositional and doping superlattices of nanodimensions enable the tailoring of advanced materials with novel properties, owing to the domination of quantum effects over the free-car- rier distribution in this size regime [1,2]. Modern growth techniques such as molecular beam epitaxy (MBE) have enabled the formation of superlattices of monolayer dimensions and, thus, the practical realization of introducing artificial periodicity and, consequently, the band structure in a desired way, an example of which is the formation of δ-doped silicon structures. Since this process involves the for- mation of a dopant layer sandwiched between the silicon layers, the study of metal layer growth on sin- gle-crystal silicon surfaces has assumed importance. Such studies also address the issue of band-bend- ing and Schottky barrier formation that are dependent on surface and interface states. The properties of metal/semiconductor interfaces have been a topic of great technological interest and scientific challenge over several decades. Multidirectional approaches to understand the deviations from the Schottky–Mott rule have yielded novel results, aiding the understanding at the atomistic level. It is now clear that apart from just metal-induced gap states (MIGS), there are other factors involved at the real metal/semicon- ductor contact, such as defect densities, growth kinetics, and interfacial strain. Since the kinetics of for- mation plays a dominant role in determining the interface and overlayer characteristics, a surface sci- *Pure Appl. Chem. 74, 1489–1783 (2002). An issue of reviews and research papers based on lectures presented at the 2 nd IUPAC Workshop on Advanced Materials (WAM II), Bangalore, India, 13–16 February 2002, on the theme of nanostructured advanced materials. ‡ Corresponding author: Fax: +91-11-5852678; E-mail: prasad@csnpl.ren.nic.in