Vv. Afanasev et A. Stesmans, ANALYSIS OF NEAR-INTERFACIAL SIO2 TRAPS USING PHOTON-STIMULATED ELECTRON-TUNNELING, Microelectronic engineering, 36(1-4), 1997, pp. 149-152
Semiconductor/insulator interface states with energy levels above the
semiconductor bandgap have so far escaped direct detection. From exper
iments on the photon stimulated tunneling of electrons at the interfac
es of SiO2 with Si and SiC, direct evidence is provided for the presen
ce of defects with electron binding energy of 2.8 eV relative to the S
iO2 conduction band edge - well above the silicon bandgap. The defects
are located in the near interfacial oxide layer, their density being
sensitive to the silicon enrichment of SiO2. A remarkable correlation
is observed between the optically stimulated tunneling transitions and
the dark conductivity for various oxide layers, revealing the defects
discovered as the common origin of trap-assisted electron injection p
henomena in SiO2.