Influences of Doping and Crystal Orientation on Surface Roughening upon Alcohol Grafting onto Silicon Hydride

Joline Tung,Yit Khung

doi:10.3390/app7080859

Joline Tung, Yit Khung

Open Access

https://doi.org/10.3390/app7080859

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Abstract

An alcohol bearing alkyne was thermally grafted to both p-type and n-type silicon (111) and (100) substrate of comparable doping levels and surface flatness. The surface topography as well as the surface chemistry was examined via atomic force microscopy (AFM), X-ray photoelectron spectroscopy (XPS) and water contact angle measurements. P-type silicon (111) was observed to experience roughening on the surface upon functionalization while n-type silicon (111) surfaces remained relatively unchanged. When the alcohol was grafted onto silicon (100) surface, the roughening effect was found to be even more profound for the p-type while the effects were marginal for the n-type surfaces. Both roughening effects were attributed to the differential weakening of the Si–Si backbond induced by majority carriers in p- and n-type silicon while (111) was observed to be able to resist the roughening effect better and this was explained by the notion of its denser adatom surface packing as well as the presence of surface defects.

Highlights

Hydrosilylation on silicon surface remains a relatively useful technique for the passivation of silicon surface with organic monolayers but the process is extremely sensitive towards water contamination due to the susceptibility of water molecules reacting with surface radicals [1,2,3]
Si–C linkage can proceed at lower temperatures (
We established that alcohol interfacing at elevated temperatures to the silicon surface might induce surface roughening that is highly dependent on the doping as well as the crystal orientation of the substrate

Summary

Introduction

Hydrosilylation on silicon surface remains a relatively useful technique for the passivation of silicon surface with organic monolayers but the process is extremely sensitive towards water contamination due to the susceptibility of water molecules reacting with surface radicals [1,2,3]. It was increasingly clear that even at temperatures above 150 ◦ C, the nominal silicon hydride homolysis may not be the initiating process on silicon surfaces as described by Coletti et al and there might be the contention of surface silicon dimerization, especially in ultra high vacuum conditions [13]. Such a description may not be fully accepted within the scientific community currently. With regards to UV photoionization, the process has been under some

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