A high-resolution photoemission study of confined metal systems on InAs(110)

Metal deposition on semiconductor substrates can give rise to various low-dimensional ordered structures. Their insulating or metallic character can depend on the spatial confinement and on the different atomic geometry. High-resolution and high-luminosity ultraviolet photoelectron spectroscopy is the best suited technique to follow the spectral density evolution of low-dimensional metallic systems deposited on narrow-gap semiconductors, in the energy gap region and close to the Fermi level. Simple metals, like alkali metals (Cs), produce one-dimensional insulating chains on InAs(110), while Bi builds up different symmetry structures with insulating [(1×1)] or metallic [(1×2)] character, and Ag presents an insulator-to-metal transition as a function of coverage. Moreover, high-resolution photoemission brings to light clear two-dimensional quantized eigenstates due to the quantum confinement of accumulated electron charge within the InAs conduction band, induced by InAs surface modifications.