Band-edge electronic structures, and pre-existing defects in remote plasma deposited (RPD) non-crystalline (nc-) SiO_2 and GeO_2

摘要

Three inter-related topics are addressed: (i) ray spectroscopy (XAS) studies of remote plasma deposited (RPD) nc-SiO_2 and nc-GeO_2 emphasizing (a) band-edge states and (b) pre-existing bonding defects: (ii) interpretation of X-ray absorption and photoemission spectra based on many electron theory, and (iii) band-edge electronic structure and intrinsic defects in nc-SiO_2 and nc-GeO_2 thin films and their respective interfaces with Si and Ge substrates. The most significant result is the identification of local atomic structure and medium range order (MRO) cluster in which pre-existing defects are embedded. The defects are vacated 0-atom sites in which O-atoms have never been resident. They are confined to 1 nm scale chemically-ordered clusters distributed aperiodically in quartz-structured 4-fold coordinated Si(Ce) and 2-fold coordinated 0 clusters comprised of 12-atom Si-0 and Ge-0 regular rings. The vacated site defects are formed during processing and annealing, reducing macroscopic strain. Finally, they are qualitatively different, and therefore readily distinguished from defects introduced by electrical stressing, and by X-ray, γ-ray or high energy electron stressing.