Surface studies of single-crystalline refractory metal low-dimensional structures

We present the results of surface investigations of novel heteroepitaxial m etallic low-dimensional structures fabricated on the basis of high-quality single-crystalline refractory-metal films (W(1 0 0) with thickness of 30-20 00 Angstrom on r-plane sapphire). Films were grown by laser ablation deposi tion technique. Procedure consisting of soft ion bombardment and annealing at 1200-1300 K in UHV allowed to obtain atomically clean (1 0 0) film surfa ce (without oxygen and carbon contamination) with four-fold symmetry LEED p attern typical for refractory metals. Study of atomic and electronic struct ures and composition of the film surface was performed by LEED, AES, and UP S techniques. UPS spectra of these low-dimensional metallic systems are pre sented and compared with electronic structure of bulk single crystals. (C) 2001 Elsevier Science B.V. All rights reserved.