The role of second-neighbor effects in photoemission: Are silicon surfaces and interfaces special?

Abstract

A widely used assignment scheme for Si 2p core-level photoemission studies of silicon oxidation relies solely on the formal oxidation state of the silicon. The tacit assumption of this assignment methodology is that second-neighbor effects have no measurable effect on observed Si 2p binding energies. In this letter, new experiments are combined with literature precedents to make the case that the second-neighbor effects play an important role in determining binding energy shifts.

Reflection–absorption infrared investigation of hydrogenated silicon oxide generated by the thermal decomposition of H8Si8O12 clusters

“…The total intensity of the feature derived from H-SiO 3 cluster fragments, centered at ϳϪ3.6 eV, loses over 50% of its original intensity after heating. 19,[42][43][44][45] A new feature, centered at ϳϪ2.7 eV, is also observed that is ϳ60% as intense as the broad feature at Ϫ3.6 eV. The ratio of oxidized silicon to bulk silicon remains constant and the total oxygen ͑measured by the O 1s core level͒ is the same before and after heating.…”

Ultrathin (<4 nm) SiO2 and Si–O–N gate dielectric layers for silicon microelectronics: Understanding the processing, structure, and physical and electrical limits

“…More recently this traditional interpretation has been questioned. 133,136,139,166,167 It has been argued that second nearest neighbor effects can lead to additional shifts of Si 2p levels, making quantitative analysis of suboxide states even more complicated. In either case, current estimates of the total concentration of Si in the suboxide states are between one and two monolayers, whereas an atomically abrupt interface would result in one monolayer of suboxide.…”

“…18, as a Si atom with n (n ϭ1,2,3) O bonds in the first coordination sphere, 122,124,125,130,161 is currently under debate. 133,136,165,167,605 An alternate interpretation derives from experiments illustrated in Fig. 19.…”

Short-range order and luminescence in amorphous silicon oxynitride

“…binding energies of the Si2p, N 1s and 0 1s levels increase with increase in the 0 content. According to the additive effect, the charge transfer per Si-0 bond and Si-N bond should be constant, which is independent of the types of atom other than the nearest neighbour (Pasquarello et al 1995, Zhang et al 1998. That is the binding energies of the N 1s and 0 1s levels should be constant and do not depend on the chemical composition of a-SiO,N,.…”