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

We present the results of surface investigations of novel heteroepitaxial metallic low-dimensional structures fabricated on the basis of high-quality single-crystalline refractory-metal films (W(1 0 0) with thickness of 30–2000 Å on r-plane sapphire). Films were grown by laser ablation deposition technique. Procedure consisting of soft ion bombardment and annealing at 1200–1300 K in UHV allowed to obtain atomically clean (1 0 0) film surface (without oxygen and carbon contamination) with four-fold symmetry LEED pattern typical for refractory metals. Study of atomic and electronic structures and composition of the film surface was performed by LEED, AES, and UPS techniques. UPS spectra of these low-dimensional metallic systems are presented and compared with electronic structure of bulk single crystals