Chemically modified Si(111) surfaces simultaneously demonstrating hydrophilicity, resistance against oxidation, and low trap state densities

Abstract

Chemically modified Si(111) surfaces have been prepared through a series of wet chemical surface treatments that simultaneously show resistance towards surface oxidation, selective reactivity towards chemical reagents, and areal defect densities comparable to unannealed thermal oxides. Specifically, grazing angle attenuated total reflectance infrared and X-ray photoelectron (XP) spectroscopy were used to characterize allyl-, 3,4-methylenedioxybenzene-, or 4-[bis(trimethylsilyl)amino]phenyl-terminated surfaces and the subsequently hydroxylated surfaces. Hydroxylated surfaces were confirmed through reaction with 4-(trifluoromethyl)benzyl bromide and quantified by XP spectroscopy. Contact angle measurements indicated all surfaces remained hydrophilic, even after secondary backfilling with CH 3-groups. Surface recombination velocity measurements by way of microwave photoconductivity transients showed the relative defectcharacter of as-prepared and aged surfaces. The relative merits for each investigated surface type are discussed.

Decoupling Effects of Surface Recombination and Barrier Height on p-Si(111) Photovoltage in Semiconductor|Liquid Junctions via Molecular Dipoles and Metal Oxides

“…The long lifetimes observed for both p-nitrophenyl (S = 36 ± 9 cm s −1 ) and the purely methylated sample (22 ± 2 cm s −1 ) are indicative of high-fidelity, low-defect-density Si(111) surfaces, as reported previously. 46,48 Indeed, S values for intrinsic Si(111) wafers uniformly functionalized with bulky hydrocarbons, 49 thienyl, 42 and aromatic amines 50 have exhibited S values in the range of 20−190 cm s −1 indicating a minimal number of surface defects. Conversely, the mdinitrophenyl substrate exhibited a very high S value (4004 ± 51 cm s −1 ), consistent with the surface oxidation (SiO x ) observed in the XP spectrum.…”

Silicon – single molecule – silicon circuits

“…Utilising control over both the properties of the silicon contacts and the bridging molecule, 8,28,[30][31][32][33] applications can be envisaged to field-effect transistors 25,30,34,35 perhaps for biomedical applications, 29 electrochemical applications 36,37 including sensing, 38 polymer engineering, 39 hydrophobicity, 40 quantum-dot photonics, 41 photoluminescence, 42 light harvesting and usage, 43,44 bioimaging, biosensing, and cancer treatment, 45,46 as well as molecular-electronics applications. 31,36,[47][48][49][50][51] Silicon-molecule-metal junctions can also be envisaged and would have useful properties, by analogy to results found for GaAs-molecule-Au junctions.…”

Spontaneous S–Si bonding of alkanethiols to Si(111)–H: towards Si–molecule–Si circuits

“…E-mail: nadim.darwish@ curtin.edu.au application, SAMs could replace SiO 2 as the insulating material in eld-effect transistors and other devices, providing better structural and chemical control, 27,[31][32][33] leading even to biomedical applications. 34 Devices in which the interface forms a critical component 10 include: quantum-dot photonics, 35 light harvesting and usage, 36,37 photoluminescence, 38 general electrochemical applications 39 including sensing, 40 polymer engineering, 41 hydrophobicity, 42 general electrochemical sensors, 43 bioimaging, biosensing, and cancer treatment, 44,45 as well as molecular-electronics applications. 26,39,[46][47][48][49][50] Mostly the strategies used for making covalent bonds to silicon 51 have involved conditions considered harsh for silicon engineering, including: radical initiators, 30,52,53 Lewis acids, 54 Grignard reagents, 29,55 electrograing, 56 and microwave 57 or UV-visible irradiation, [58][59][60] with many processes also requiring signicant heating.…”