Probing defects at interfaces and interlayers of low-dimensional Si/insulator (HfO_2; LaAlO_3) structures by electron spin resonance

摘要

Electron spin resonance (ESR) spectroscopy enables to assess on atomic scale the nature and structural aspects of interfaces and interlayers in semiconductor/insulator hetero structures. This has been applied to (10 0)/insulator entities with nrn-thin amorphous layers of HfO_2 and LaAlO_3 of high dielectric constant (> 12) grown on clean (100)Si by atomic layer chemical vapor deposition and molecular beam deposition, respectively. Through analysis and monitoring of the occurring embedded paramagnetic point defects, including P_b-type defects, E', and EX, as a function of VUV irradiation and post-deposition heat treatment, basic information as to the nature, quality, and thermal stability of the interface and interfacial regions has been attained. On the basis of the analysis of P_b-type defects (P_(b0), P_(b1)), archetypal for the Si/SiO_2 interface, the (100)Si/LaAlO_3 stack is found to be truly abrupt, i.e., no evidence for an Si/SiO_(2(x))-type transition in contrast with the Si/HfO_2 entity, where the interface is found to be Si/SiO_(2(x))) type in the as-grown state. Analysis as a function of post-deposition heating indicates the Si/LaAlO_3 interface to remain stable and abrupt up to T_(an)～800 ℃, above which an Si/SiO_2-type interface develops, while that in Si/HfO_2 evolves to one of closely standard Si/SiO_2 quality, with an SiO_2 interlayer of good quality. The differences in behavior of the studied Si/insulator stacks are discussed in a comparative analysis.