Band offsets for ultrathin SiO2 and Si3N4 films on Si(111) and Si(100) from photoemission spectroscopy

Abstract

High resolution soft x-ray photoelectron spectroscopy with synchrotron radiation is used to study the interfaces of SiO 2 /Si(111), SiO 2 /Si(100), Si͑111͒/Si 3 N 4 , and SiO 2 /Si 3 N 4 for device-quality ultrathin gate oxides and nitrides. The thin oxides and nitrides were grown by remote plasma deposition at a temperature of 300°C. Aftergrowth samples were further processed by rapid thermal annealing for 30 s at various temperatures from 700 to 950°C. The Si͑111͒/Si 3 N 4 samples were air exposed and formed a thin ϳ6 Å SiO 2 layer with a Si(2p) core-level shift of 3.9 eV, thus allowing us to study both the Si͑111͒/Si 3 N 4 and SiO 2 /Si 3 N 4 interfaces with a single type of sample. We obtain band offsets of 4.54Ϯ0.06 eV for SiO 2 /Si(111) and 4.35Ϯ0.06 eV for SiO 2 /Si(100) with film thicknesses in the range 8-12 Å. The Si͑111͒/Si 3 N 4 nitrides show 1.78Ϯ0.09 eV valence-band offset for 15-21 Å films. This value agrees using the additivity relationship with our independent photoemission measurements of the nitride-oxide valence-band offset of 2.66Ϯ0.14 eV. However, we measure a substantially larger SiO 2 /Si 3 N 4 ⌬E V value of 3.05 eV for thicker ͑ϳ60 Å͒ films, and this indicates substantial differences in core-hole screening for films of different thickness due to additional silicon substrate screening in the thinner ͑15-21 Å͒ films.

First principles investigation of defect energy levels at semiconductor-oxide interfaces: Oxygen vacancies and hydrogen interstitials in the Si–SiO2–HfO2 stack

“…In particular, we obtained a 4.4 eV valence band offset between silicon and amorphous SiO 2 in accord with the measured value. 49,50 For the interface between silicon and monoclinic HfO 2 , we obtained a valence band offset of 2.9 eV, very close to the measured value of 3.0 eV. 51,52 This level of agreement provides confidence for the quantitative determination of defect levels with respect to the silicon band edges.…”

High-Resolution Soft X-ray Photoelectron Spectroscopic Studies and Scanning Auger Microscopy Studies of the Air Oxidation of Alkylated Silicon(111) Surfaces

“…[29][30][31] Previous core photoelectron spectroscopic studies of the Si(111)/SiO 2 interface have shown that Si(I) and Si(III) are more abundant than Si 2+ because disrupting an atomically flat (111) surface through layer-by-layer oxidation will cleave either 1 or 3 Si tetrahedral bonds. 6,14,[32][33][34][35] Two Si bonds will be cleaved only at step edges and etch defects, which are a minor component of Si(111) surfaces prepared in this manner. Additionally, the native oxide that forms on an unpassivated Hor Cl-terminated Si(111) surface covers all available oxidation states of Si, from Si(I) to Si(IV), with the majority of the oxide signal appearing as Si(IV) species.…”

Comparative study of GeO2/Ge and SiO2/Si structures on anomalous charging of oxide films upon water adsorption revealed by ambient-pressure X-ray photoelectron spectroscopy

“…In particular, for the latter system, its origin has been widely discussed on the basis of the final-state effect and charge trapping. [37][38][39][40][41] We calculated the change in the energy difference DE GeO 2 or DE SiO 2 at an elevated RH from that at the lowest RH or in UHV for each sample, which is defined as DE change hereafter. Namely, for both the GeO 2 /Ge and SiO 2 /Si samples…”