Invited Paper SS2-ThM3
Preparation and Characterization of β-Si₃N₄ Surfaces

Thursday, October 18, 2007, 8:40 am, Room 611

β-Si₃N₄ is an important electronic material with numerous device applications. Yet, in contrast to other such materials, relatively little is known about its fundamental surface properties. This talk will discuss recent theoretical and experimental work relating to the preparation and properties of β-Si₃N₄ surfaces. The growth and characterization (via IR spectroscopy and XPS) of thin films will be examined, together with methods for preparing an atomically-clean and stoichiometric surface in UHV. Ab-initio calculations of the physical and electronic structure of the (0001) surface, which provide insight into the interpretation of electron-spectroscopic data, will be described. In particular the nature of the relaxation and the electronic states at the surface will be discussed. Data from Auger, photoemission (UPS and XPS) and electron energy-loss spectroscopies will be examined in relation to the theoretical results, and preliminary chemisorption data will be presented. Strong surface-charging effects are observed in UPS and XPS which take the form of rigid shifts of the spectra by 1 eV or more with adsorption and with x-ray or VUV irradiation. These will be examined in the context of electron and hole trap states in the band gap. Brief mention will also be made of IR internal-reflection studies of wet-chemical processing of β-Si₃N₄ films.