Hard X-ray angle-resolved photoelectron spectroscopy (HARPES)

Abstract

This chapter will provide an overview of the basic principles of hard X-ray angle-resolved photoelectron spectroscopy (HARPES), which has recently emerged as a powerful technique for studying momentum-resolved bulk electronic structure of novel materials, buried interfaces and heterostructures. HARPES provides access to the bulk electronic structure of solids due to the high inelastic mean-free paths (IMFP) of the valence-band electrons emitted at high excitation energies. The first results of HARPES measurements at excitation energies of 3.24 and 5.95 keV will be presented. The systems that will be discussed are W, as a model transition-metal system to study basic principles in such HARPES experiments; GaAs, as a technologically-relevant material to illustrate the broad applicability of this new technique; and Ga1−xMnxAs, as a novel dilute ferromagnetic semiconductor material. The experimental results will be compared to free-electron final-state model calculations and more precise one-step photoemission theory including matrix element effects. Some likely future applications areas will also be discussed.