ISSN:
1089-7550
Source:
AIP Digital Archive
Topics:
Physics
Notes:
Impedance spectroscopy was used to analyze the dielectric properties of reactive ion-etched silicon/liquid junction interfaces for five different plasmas: CHF3 /Ar, CF4 , CClF3 /H2 , CClF3 /H2 +O2 ash, and O2 ash. The results were interpreted in terms of equivalent circuits, which are basically the damaged layer constituents. These elements dominate the impedance spectra and their contributions arise from two different regions inside the treated substrates: a residue overlayer and a Si-damaged layer. We have estimated the thickness of these regions. Except for the CClF3 /H2 treatment, the photoresponse of the cells is very poor. A comparison between these results and those obtained for samples not submitted to the reactive ion etching (RIE) processes in the same electrochemical cell will be presented. The effect of wet etchings, in buffered HF, 2M KOH, and a photoetching in 0.5% HF solutions, on the performance of the photoelectrochemical cells will be discussed. The results indicate that the CHF3 /Ar RIE promotes a deeper damage, compared with the CF4 RIE, and it cannot be removed by the chemical treatments that were used. The observed shifts of the flat-band potential, shown by the RIE-damaged substrates, are associated with the accumulation of positive charges at the semiconductor interface. The O2 ash treatment partially recovers the surface damage by removing these charges but is responsible for the formation of an insulating overlayer.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1063/1.344310
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