Flatband Potential Studies at the n‐Si/Electrolyte Interface by Electroreflectance and C‐V Measurements

Abstract

The properties of the n-St electrode in both aqueous and organic solution for nonstabilizing conditions were studied by the electrorefleetance and capacitance techniques. A shift of the flatband potential in the anodic direction up to 0 VseE has been observed for both solutions and was more pronounced for the aqueous one. The strong influence of polarization under anodic potentials on the properties of the St/electrolyte junction is shown. It is demonstrated that the flatband potential shifts for solutions without a stabilizing agent is caused by the slow oxidation process and related interface state evolution. Anomalously high electroreflectanee signals have been observed for the potentials where a capacitance peak associated with the interface states is detected. We suppose the interaction of hydrogen-related species in a subsurface Si layer with interface states to be responsible for this specific electrorefleetance modulation.

A Novel Composite Anode: The Electrooxidation of Organic Molecules via Formation of Highly Energetic Holes

“…The complex electrode structure makes it difficult to predict the detailed potential distribution within the electrode with any degree of certainty. For the isolated components, n -Si and n -TiO 2 , the flat-band potentials are both close to 0.1 V , and the work function of gold is ca. 0.6 V (taking the potential of the SHE as 4.44 eV versus vacuum) .…”

The Role of the Flat-Band Potential in Porous Silicon Formation

“…Unfortunately, the direct determination of the flatband potential for p-type silicon is a difficult exercise, with the Mott-Schottky technique yielding inconsistent values as the silicon/electrolyte interface deviates from ideal behavior. 2 Alternative methods to determine the flatband potential include electroreflectance measurements [3][4][5] and high frequency resistrometry with and without illumination. 2,6 Although potentially more reliable than capacitance measurements these techniques are experimentally more challenging to conduct, which when combined with the safety hazards of working with HF means that their use has been restricted to dilute solutions (typically 1 wt%).…”

Structure–Property Relationships in Redox-Derivatized Metal–Insulator–Semiconductor (MIS) Photoanodes

“…and NiRu Prussian blue (NiRuPB) analogs can undergo rapid and reversible redox transfer at formal potential (E 0' ) values of approximately 0.45 and 0.90 V vs saturated calomel electrode (SCE), respectively, 27,28 which are typically more positive than the flat-band potential of n-Si. 29 If their immobilization at the MIS surface can increase the Schottky barrier at the MIS interface, they could be useful for their electrocatalytic properties as Co, Fe, Ru, and Ni have been considered as excellent active sites for the OER reaction. 30 In particular, CoFePB has been regarded as a promising OER catalyst 31,32 and has been coupled with several photoanodes such as BiVO 4 , [33][34][35][36] α-Fe 2 O 3 37 , TiO 2 , 38 , and Si nanowires.…”

“…Prussian blue (PB) analogues have been recognized as one type of coordination polymers constituted of transition-metal cations bridged via cyanide ions . CoFe Prussian blue (CoFePB) and NiRu Prussian blue (NiRuPB) analogues can undergo rapid and reversible redox transfer at formal potential ( E 0′ ) values of approximately 0.45 and 0.90 V vs saturated calomel electrode (SCE), respectively, , which are typically more positive than the flat-band potential of n-Si . If their immobilization at the MIS surface might influence the Schottky barrier at the MIS interface, they may be useful for their electrocatalytic properties as Co, Fe, Ru, and Ni have been considered as excellent active sites for the OER reaction .…”