The Chemical Origin of Defects on Silicon Dioxide Exposed to Ethanol

Abstract

The adsorption and reaction of ethanol on the metal-free, pure silicon dioxide surface have been studied as a model system to explore the chemical origin of the defects which are detrimental in the gate oxide exposed to chemical vapors. In addition to molecular adsorption, ethanol decomposed to the extent that a variety of species including ethyl, ethoxy, and hydroxyl were produced even at the surface temperature of 115 K. The silicon dioxide surface was selective for the formation of acetaldehyde through cleavage of the C-H bond. The bare surface, however, was more selective for ethanol conversion to ethylene than the surface covered by fragments and products. Comparison of static secondary ion mass spectra taken from the surface exposed to deuterated and nondeuterated ethanol, respectively, showed that the C-H, Et-OH, and EtO-H bonds were disrupted during the surface decomposition of ethanol. Hydroxyl hydrogen of ethanol readily exchanged with silanol hydrogen of the surface. The formation of Si-H and SiO-H bonds suggests that hydrogen concentration will increase on the metal-free silicon dioxide surface exposed to organic vapors. Its implication to the generations of defects in the silicon dioxide framework and of the stress-induced leakage current will be discussed.

Electrostatic Limit of Detection of Nanowire‐Based Sensors

“…This negatively charged layer acts as a molecular gate causing depletion in the n‐doped region and resulting in a more positive CPD (more p‐type) of the nanowire. The highly complex interaction of ethanol with an SiO 2 surface was studied in previous works, e.g., by Chang and Shu . KPFM measurements are supported by I D – V D characteristics of the EFN device (Figure c) showing the decrease in I D following ethanol adsorption.…”

Silica Surface Features and Their Role in the Adsorption of Biomolecules: Computational Modeling and Experiments

“…193,194 Work comparing SIMS and XPS and using chemical derivatization has shown that the m/e = 45 (SiOH + ) SIMS peak may be used to quantify total silanol surface densities, which was thus measured at 2.6 nm -2 in Ref. 194 Reflection attenuation IR also allowed to observe S2R sites. 142 SiO x films on silicon can grow up to at least 1 micrometer thick while still allowing the use of surface techniques such as specular x-ray reflectivity and SANS (small-angle neutron scattering), 195 and this would be expected to remove the structural influence of the substrate.…”

Mechanistic Study on the Lewis Acid Catalyzed Synthesis of 1,3-Butadiene over Ta-BEA Using Modulated Operando DRIFTS-MS

“…1710 cm −1 is present when pure CA is adsorbed on Ta-BEA (Figure S10) and none more redshifted at 1690 cm −1 , indicating that EtOH, either from the gasphase or preadsorbed, is needed to form the latter species and that it could originate from a reaction intermediate. 44 Additionally, we performed a modulation experiment, where the catalyst was first saturated with EtOH, followed by periodically switching to pure CA. The MS signals (Figure S11) reveal similar but more pronounced patterns than those in Figure 5.…”