Chemistry - Conference Items

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Adsorption of alkanethiol self-assembled monolayers on sputtered gold substrates for atomic nanolithography applications
(The Electrochemical Society, 2004-01) O'Dwyer, Colm
A detailed study of the self-assembly and coverage by 1-nonanethiol of sputtered Au surfaces using molecular resolution atomic force microscopy (AFM) and scanning tunneling microscopy (STM) is presented. The monolayer self-assembles on a smooth Au surface composed predominantly of {111} oriented grains. The domains of the alkanethiol monolayer are observed with sizes typically of 5-25 nm, and multiple molecular domains can exist within one Au grain. STM imaging shows that the (4 × 2) superlattice structure is observed as a (3 × 2√3) structure when imaged under noncontact AFM conditions. The 1-nonanethiol molecules reside in the threefold hollow sites of the Au{111} lattice and aligned along its [112] lattice vectors. The self-assembled monolayer (SAM) contains many nonuniformities such as pinholes, domain boundaries, and monatomic depressions which are present in the Au surface prior to SAM adsorption. The detailed observations demonstrate limitations to the application of 1-nonanethiol as a resist in atomic nanolithography experiments to feature sizes of ~20 nm.
Anodic behavior of InP: film growth, porous structures and current oscillations.
(Electrochemical Society, 2003-04) Buckley, D. Noel; O'Dwyer, Colm; Harvey, E.; Melly, T.; Sutton, David; Newcomb, Simon B.
We review our recent work on the anodization of InP in KOH electrolytes. The anodic oxidation processes are shown to be remarkably different in different concentrations of KOH. Anodization in 2 - 5 mol dm-3 KOH electrolytes results in the formation of porous InP layers but, under similar conditions in a 1 mol dm-3 KOH, no porous structure is evident. Rather, the InP electrode is covered with a thin, compact surface film at lower potentials and, at higher potentials, a highly porous surface film is formed which cracks on drying. Anodization of electrodes in 2 - 5 mol dm-3 KOH results in the formation of porous InP under both potential sweep and constant potential conditions. The porosity is estimated at ~65%. A thin layer (~ 30 nm) close to the surface appears to be unmodified. It is observed that this dense, near-surface layer is penetrated by a low density of pores which appear to connected it to the electrolyte. Well-defined oscillations are observed when InP is anodized in both the KOH and (NH4)2S. The charge per cycle remains constant at 0.32 C cm-2 in (NH4)2S but increases linearly with potential in KOH. Although the characteristics of the oscillations in the two systems differ, both show reproducible and well-behaved values of charge per cycle.
Anodic oxidation of InP in KOH electrolytes
(Electrochemical Society, 2002-10) O'Dwyer, Colm; Melly, T.; Harvey, E.; Buckley, D. Noel; Cunnane, V. J.; Sutton, David; Serantoni, M.; Newcomb, Simon B.
The anodic behavior of InP in 1 mol dm-3 KOH was investigated and compared with its behavior at higher concentrations of KOH. At concentrations of 2 mol dm-3 KOH or greater, selective etching of InP occurs leading to thick porous InP layers near the surface of the sustrate. In contrast, in 1 mol dm-3 KOH, no such porous layers are formed but a thin surface film is formed at potentials in the range 0.6 V to 1.3 V. The thickness of this film was determined by spectroscopic ellipsometry as a function of the upper potential and the measured film thickness corresponds to the charge passed up to a potential of 1.0 V. Anodization to potentials above 1.5 V in 1 mol dm- 3 KOH results in the growth of thick, porous oxide films (~ 1.2 µm). These films are observed to crack, ex-situ, due to shrinkage after drying in ambient air. Comparisons between the charge density and film thickness measurements indicate a porosity of approximately 77% for such films.
AuxAg1-x alloy seeds: A way to control growth, morphology and defect formation in Ge nanowires
(2012-06) Biswas, Subhajit; Holmes, Justin D.
Germanium (Ge) nanowires are of current research interest for high speed nanoelectronic devices due to the lower band gap and high carrier mobility compatible with high K-dielectrics and larger excitonic Bohr radius ensuing a more pronounced quantum confinement effect [1-6]. A general way for the growth of Ge nanowires is to use liquid or a solid growth promoters in a bottom-up approach which allow control of the aspect ratio, diameter, and structure of 1D crystals via external parameters, such as precursor feedstock, temperature, operating pressure, precursor flow rate etc [3, 7-11]. The Solid-phase seeding is preferred for more control processing of the nanomaterials and potential suppression of the unintentional incorporation of high dopant concentrations in semiconductor nanowires and unrequired compositional tailing of the seed-nanowire interface [2, 5, 9, 12]. There are therefore distinct features of the solid phase seeding mechanism that potentially offer opportunities for the controlled processing of nanomaterials with new physical properties. A superior control over the growth kinetics of nanowires could be achieved by controlling the inherent growth constraints instead of external parameters which always account for instrumental inaccuracy. The high dopant concentrations in semiconductor nanowires can result from unintentional incorporation of atoms from the metal seed material, as described for the Al catalyzed VLS growth of Si nanowires [13] which can in turn be depressed by solid-phase seeding. In addition, the creation of very sharp interfaces between group IV semiconductor segments has been achieved by solid seeds [14], whereas the traditionally used liquid Au particles often leads to compositional tailing of the interface [15] . Korgel et al. also described the superior size retention of metal seeds in a SFSS nanowire growth process, when compared to a SFLS process using Au colloids [12]. Here in this work we have used silver and alloy seed particle with different compositions to manipulate the growth of nanowires in sub-eutectic regime. The solid seeding approach also gives an opportunity to influence the crystallinity of the nanowires independent of the substrate. Taking advantage of the readily formation of stacking faults in metal nanoparticles, lamellar twins in nanowires could be formed.
Branched PEI capped gold nanoparticles in water for siRNA delivery to cancer cells
(TechConnect, 2017-05) Rahme, Kamil; Guo, Jianfeng; Biswas, Subhajit; O'Driscoll, Caitríona M.; Holmes, Justin D.; Science Foundation Ireland; Conseil National de la Recherche Scientifique
Herein we describe a simple method for the synthesis of different sizes of polyethylenimine-capped gold nanoparticles (AuNPs-PEI) in water and assess their potential to deliver siRNA or other therapeutic agents to cancer cells. AuNP-PEI with diameters ranging between 25-150 nm have been synthesised in aqueous solutions using PEI (25 KD and 2KD) as capping ligands and using hydroxylamine-O-sulfonic acid or ascorbic acid as reducing agents. Different parameters were found to affect the final size of nanoparticles core (i.e. gold salt concentrations, PEI molecular weight/concentrations, and temperature). The obtained AuNP-PEIs were fully characterized using UV-visible spectroscopy, Electron Microscopy (EM), and Dynamic Light Scattering (DLS). UV-visible spectra clearly showed that the synthesized particles have size dependent optical properties with a plasmon band shift to longer wavelengths, as the size of the AuNP core was increased. In addition, DLS analysis indicated that all samples were nearly monodisperse with one size distribution and a polydispersity index (PDI) of about 0.15 (Std 0.03). EM analysis indicated that AuNPs-PEI were nearly spherical in shape. Zeta (ζ) potential measurements showed that all AuNPs-PEI samples were positively charged with a ζ-potential in the range of 38 (Std 5 mV), leading to a very high stability of the colloidal solution for several months when stocked at 4 C. Furthermore, the potential application of AuNP-PEIs in siRNA delivery to PC-3 prostate cancer cells was investigated. The ability of AuNP-PEIs to complex siRNA was analysed by gel electrophoresis. Results indicated that AuNP-PEI 2KD and AuNP-PEI 25KD could complex siRNA at MR0.5 and MR0.25 onwards, respectively, suggesting that AuNP-PEI 25KD has a better siRNA binding capacity than AuNP-PEI 2KD. Cellular uptakes were also performed using PC-3 cancer cells. Results following 24 h incubation indicated that AuNP-PEI 25KD achieved significantly higher fluorescein-positive cells (~ 98%) relative to that of AuNP-PEI 2KD (~ 5%), suggesting that AuNP-PEI 25KD, but not AuNP-PEI 2KD, could deliver siRNA into cells. Finally, we have also demonstrated that the surface of AuNPs-PEI can be further conjugated with thiolated polyethylene glycol (SH-PEG) onto AuNPs surface. Moreover, we have previously showed that covalently bonded targeting ligand (such as Anisic Acid or Folic acid) could be also chemically grafted on PEI, leading therefore to a multifunctional nanoparticle that may be promising in the field of Nanobiotechnology and Nanomedicine.
Characterization of resistivity of Sb2S3 semiconductor nanowires by conductive AFM and in-situ methods
(Trans Tech Publications, 2011-04) Bukins, J.; Kunakova, Gunta; Birjukovs, P.; Prikulis, Juris; Varghese, Justin M.; Holmes, Justin D.; Erts, Donats; Medvids, Arturs
Conductive AFM and in situ methods were used to determine contact resistance and resistivity of individual Sb2S3 nanowires. Nanowires were deposited on oxidized Si surface for in situ measurements and on Si surface with macroelectrodes for conductive AFM (C-AFM) measurements. Contact resistance was determined by measurement of I(V) characteristics at different distances from the nanowire contact with the macroelectrode and resistivity of nanowires was determined. Sb2S3 is a soft material with low adhesion force to the surface and therefore special precautions were taken during measurements.
Comparison of oscillatory behavior on InP electrodes in KOH solutions
(Electrochemical Society, 2002-10) O'Dwyer, Colm; Melly, T.; Harvey, E.; Buckley, D. Noel; Cunnane, V. J.; Sutton, David; Newcomb, Simon B.
The observation of current oscillations under potential sweep conditions when an n-InP electrode is anodized in a KOH electrolyte is reported and compared to the oscillatory behavior noted during anodization in an (NH4)2S electrolyte. In both cases oscillations are observed above 1.7 V (SCE). The charge per cycle was found to increase linearly with potential for the InP/KOH system but was observed to be independent of potential for the InP/(NH4)2S system. The period of the oscillations in the InP/KOH was found to increase with applied potential. In this case the oscillations are asymmetrical and the rising and falling segments have a different dependence on potential. Although the exact mechanism is not yet know for either system, transmission electron microscopy studies show that in both cases, the electrode is covered by a thick porous film in the oscillatory region.
Dendrigraft poly-L-lysine (d-PLL) coated gold nanoparticles in water for siRNA delivery to prostate cancer cells
(TechConnect, 2018-05) Rahme, Kamil; Minassian, G.; Ghanem, Esther; Souaid, Eddy; Guo, Jianfeng; O'Driscoll, Caitríona M.; Holmes, Justin D.; National Council for Scientific Research
Herein we describe a simple method for the synthesis of dendrigraft poly-L-lysine (d-PLL) coated different sizes gold nanoparticles in water (AuNPs-d-PLL) as potential to delivery vehicles of siRNA to PC-3 prostate cancer cells. AuNPs-d-PLL with diameters ranging between 50-120 nm have been synthesised in aqueous solutions using d-PLL (7 KD) as a capping ligand, and ascorbic acid as a reducing agent. The size of the resulting AuNPs was found to depend on several parameters (i.e. the concentrations of the gold salt, ascorbic d-PLL and temperature). The obtained AuNPs-d-PLL were characterized using UV-visible spectroscopy (UV-vis), Scanning Electron Microscopy (SEM), and Dynamic Light Scattering (DLS). The ability to PEGylate the AuNPs-d-PLL with SH-PEG-OCH3 and SH-PEG-Folate was demonstrated via DLS and zeta potential mesurements, their capacity to complex siRNA was verified (DLS, gel electrophoresis), and transfer of AuNPs-d-PLL-PEG-FA.siRNA to PC-3 cells was investigated.
Development of an electrochemical caffeine sensor for PAT application in the food and beverage industry
(Institute of Electrical and Electronics Engineers (IEEE), 2017-10) Scanlon, Shauna; Messina, Walter; Moore, Eric; Rothwell, Sharon; Harrison, Scott; Irish Research Council; PepsiCo
This work reports on the development of an electrochemical sensor for on-line caffeine detection using screen printed graphite electrodes. The effects of solution pH and pre-treatment procedures on electrode performance have been discussed, as well as the modification of the electrode surface for increased electrode sensitivity. Successful caffeine determination in soft drink samples is described. The results indicate the potential of electrochemical sensors to compare and compete with the current off-line methods of caffeine analysis, such as HPLC, allowing for both a reduction in time and cost of product quality analysis. The successful performance of the screen printed electrode, as well as its low cost and small dimensions, will allow for efficient integration into a multi-parameter device for on-line quality control analysis.
Electrochemical pore formation on InP in alkaline solutions
(Electrochemical Society, 2001-09) Harvey, E.; O'Dwyer, Colm; Melly, T.; Buckley, D. Noel; Cunnane, V. J.; Sutton, David; Newcomb, Simon B.; Chu, S. N. G.
The surface properties of InP electrodes were examined following anodization in (NH4)2S and KOH electrolytes. In both solutions, the observation of current peaks in the cyclic voltammetric curves was attributed to selective etching of the substrate and a film formation process. AFM images of samples anodized in the sulfide solution, revealed surface pitting and TEM micrographs revealed the porous nature of the film formed on top of the pitted substrate. After anodization in the KOH electrolyte, TEM images revealed that a porous layer extending 500 nm into the substrate had been formed. Analysis of the composition of the anodic products indicates the presence of In2S3 in films grown in (NH4)2S and an In2O3 phase within the porous network formed in KOH.
Formation and characterization of porous InP layers in KOH Solutions
(Electrochemical Society, 2002-10) O'Dwyer, Colm; Buckley, D. Noel; Cunnane, V. J.; Sutton, David; Serantoni, M.; Newcomb, Simon B.
Porous InP layers were formed electrochemically on (100) oriented n-InP substrates in various concentrations of aqueous KOH under dark conditions. In KOH concentrations from 2 mol dm-3 to 5 mol dm-3, a porous layer is obtained underneath a dense near-surface layer. The pores within the porous layer appear to propagate from holes through the near-surface layer. Transmission electron microscopy studies of the porous layers formed under both potentiodynamic and potentiostatic conditions show that both the thickness of the porous layer and the mean pore diameter decrease with increasing KOH concentration. The degree of porosity, estimated to be 65%, was found to remain relatively constant for all the porous layers studied.
Formation of nanoporous InP by electrochemical anodization
(The Electrochemical Society, 2004-01) Buckley, D. Noel; O'Dwyer, Colm; Lynch, Robert P.; Newcomb, Simon B.
Porous InP layers can be formed electrochemically on (100) oriented n- InP substrates in aqueous KOH. A nanoporous layer is obtained underneath a dense near-surface layer and the pores appear to propagate from holes through the near-surface layer. In the early stages of the anodization transmission electron microscopy (TEM) clearly shows individual porous domains which appear to have a square-based pyramidal shape. Each domain appears to develop from an individual surface pit which forms a channel through this near-surface layer. We suggest that the pyramidal structure arises as a result of preferential pore propagation along the <100> directions. AFM measurements show that the density of surface pits increases with time. Each of these pits acts as a source for a pyramidal porous domain. When the domains grow, the current density increases correspondingly. Eventually, the domains meet forming a continuous porous layer, the interface between the porous and bulk InP becomes relatively flat and its total effective surface area decreases resulting in a decrease in the current density. Numerical models of this process have been developed. Current-time curves at constant potential exhibit a peak and porous layers are observed to form beneath the electrode surface. The density of pits formed on the surface increases with time and approaches a plateau value.
Formation of sub-7 nm feature size PS-b-P4VP block copolymer structures by solvent vapour process
(SPIE, 2014-03-27) Chaudhari, Atul; Ghoshal, Tandra; Shaw, Matthew T.; Cummins, Cian; Borah, Dipu; Holmes, Justin D.; Morris, Michael A.; Wallow, Thomas I.; Hohle, Christoph K.
The nanometer range structure produced by thin films of diblock copolymers makes them a great of interest as templates for the microelectronics industry. We investigated the effect of annealing solvents and/or mixture of the solvents in case of symmetric Poly (styrene-block-4vinylpyridine) (PS-b-P4VP) diblock copolymer to get the desired line patterns. In this paper, we used different molecular weights PS-b-P4VP to demonstrate the scalability of such high χ BCP system which requires precise fine-tuning of interfacial energies achieved by surface treatment and that improves the wetting property, ordering, and minimizes defect densities. Bare Silicon Substrates were also modified with polystyrene brush and ethylene glycol self-assembled monolayer in a simple quick reproducible way. Also, a novel and simple in situ hard mask technique was used to generate sub-7nm Iron oxide nanowires with a high aspect ratio on Silicon substrate, which can be used to develop silicon nanowires post pattern transfer.
Growth and characterization of anodic Films on InP in KOH and (NH4)2S
(Electrochemical Society, 2001-03) Harvey, E.; O'Dwyer, Colm; Melly, T.; Buckley, D. Noel; Cunnane, V. J.; Sutton, David; Newcomb, Simon B.
The current-voltage characteristics of InP were investigated in (NH4)2S and KOH electrolytes. In both solutions, the observation of current peaks in the cyclic voltammetric curves was attributed to the growth of passivating films. The relationship between the peak currents and the scan rates suggests that the film formation process is diffusion controlled in both cases. The film thickness required to inhibit current flow was found to be much lower on samples anodized in the sulphide solution. Focused ion beam (FIB) secondary electron images of the surface films show that film cracking of the type reported previously for films grown in (NH4)2S is also observed for films grown in KOH. X-ray and electron diffraction measurements indicate the presence of In2O3 and InPO4 in films grown in KOH and In2S3 in films grown in (NH4)2S.
Highly stable PEGylated gold nanoparticles in water: applications in biology and catalysis
(NSTI-Nanotech, 2012-08) Rahme, Kamil; Nolan, Marie-Therese; Doody, Timothy; McGlacken, Gerard P.; O'Driscoll, Caitríona M.; Holmes, Justin D.
Gold nanoparticles (Au NPs) with diameters ranging between 5-60 nm have been synthesised in water, and further stabilized with polyethylene glycol-based thiol polymers (mPEG-SH). Successful PEGylation of the Au NPs was confirmed by Dynamic Light scattering (DLS) and Zeta potential measurements. PEG coating of the Au NPs is the key of their colloidal stabilty, and its successful applications. Catalytic efficiency testing of the PEG-AuNPs were carried out on homocoupling of boronic acid. PEG-Au NPs with AuNps diameter < 30 nm were useful as catalyst in water. Finally, the PEG-Au NPs were also shown to be stable in biological fluid and not cytotoxic on B16.F10 cell line, making them attractive for further studies.
Hydroxylamine-O-sulfonic acid as a new reducing agent for the formation of nearly monodisperse gold nanoparticles in water: synthesis, characterisation and bioconjugation
(2014-06) Rahme, Kamil; Holmes, Justin D.
Gold nanoparticles (Au NPs) with diameters ranging between 15 and 150 nm have been synthesised in water. 15 and 30 nm Au NPs were obtained by the Turkevich and Frens method using sodium citrate as both a reducing and stabilising agent at high temperature (Au NPs-citrate), while 60, 90 and 150 nm Au NPs were formed using hydroxylamine-o-sulfonic acid (HOS) as a reducing agent for HAuCl4 at room temperature. This new method using HOS is an extension of the approaches previously reported for producing Au NPs with mean diameters above 40 nm by direct reduction. Functionalised polyethylene glycol-based thiol polymers were used to stabilise the pre-synthesised Au NPs. The nanoparticles obtained were characterised using uv-visible spectroscopy, dynamic light scattering (DLS) and transmission electron microscopy (TEM). Further bioconjugation on 15, 30 and 90 nm PEGylated Au NPs were performed by grafting Bovine Serum Albumin, Transferrin and Apolipoprotein E (ApoE).
Low resistivity Pt interconnects developed by electron beam assisted deposition using novel gas injector system
(IOP Publishing, 2012-07-02) Dias, R. J.; O'Regan, Colm; Thrompenaars, P.; Romano-Rodriguez, A.; Holmes, Justin D.; Mulder, J. J. L.; Petkov, Nikolay; Vol. 371; Science Foundation Ireland
Electron beam-induced deposition (EBID) is a direct write process where an electron beam locally decomposes a precursor gas leaving behind non-volatile deposits. It is a fast and relatively in-expensive method designed to develop conductive (metal) or isolating (oxide) nanostructures. Unfortunately the EBID process results in deposition of metal nanostructures with relatively high resistivity because the gas precursors employed are hydrocarbon based. We have developed deposition protocols using novel gas-injector system (GIS) with a carbon free Pt precursor. Interconnect type structures were deposited on preformed metal architectures. The obtained structures were analysed by cross-sectional TEM and their electrical properties were analysed ex-situ using four point probe electrical tests. The results suggest that both the structural and electrical characteristics differ significantly from those of Pt interconnects deposited by conventional hydrocarbon based precursors, and show great promise for the development of low resistivity electrical contacts.
A mechanistic study of anodic formation of porous InP
(The Electrochemical Society, 2003-01) O'Dwyer, Colm; Buckley, D. Noel; Sutton, David; Newcomb, Simon B.; Serantoni, M.
When porous InP is anodically formed in KOH electrolytes, a thin layer ~40 nm in thickness, close to the surface, appears to be unmodified. We have investigated the earlier stages of the anodic formation of porous InP in 5 mol dm-3 KOH. TEM clearly shows individual porous domains which appear triangular in cross-section and square in plan view. The crosssections also show that the domains are separated from the surface by a ~40 nm thick, dense InP layer. It is concluded that the porous domains have a square-based pyramidal shape and that each one develops from an individual surface pit which forms a channel through this near-surface layer. We suggest that the pyramidal structure arises as a result of preferential pore propagation along the <100> directions. AFM measurements show that the density of surface pits increases with time. Each of these pits acts as a source for a pyramidal porous domain, and these domains eventually form a continuous porous layer. This implies that the development of porous domains beneath the surface is also progressive in nature. Evidence for this was seen in plan view TEM images. Merging of domains continues to occur at potentials more anodic than the peak potential, where the current is observed to decrease. When the domains grow, the current density increases correspondingly. Eventually, domains meet, the interface between the porous and bulk InP becomes relatively flat and its total effective surface area decreases resulting in a decrease in the current density. Quantitative models of this process are being developed.
A miniaturised autonomous sensor based on nanowire materials platform: the SiNAPS mote
(Society of Photo-optical Instrumentation Engineers (SPIE), 2013-05-17) Koshro Pour, Naser; Kayal, M.; Jia, G.; Eisenhawer, B.; Falk, F.; Nightingale, Adrian M.; DeMello, John C.; Georgiev, Yordan M.; Petkov, Nikolay; Holmes, Justin D.; Nolan, Michael; Fagas, Gíorgos; European Commission; Seventh Framework Programme
A micro-power energy harvesting system based on core(crystalline Si)-shell(amorphous Si) nanowire solar cells together with a nanowire-modified CMOS sensing platform have been developed to be used in a dust-sized autonomous chemical sensor node. The mote (SiNAPS) is augmented by low-power electronics for power management and sensor interfacing, on a chip area of 0.25mm2. Direct charging of the target battery (e.g., NiMH microbattery) is achieved with end-to-end efficiencies up to 90% at AM1.5 illumination and 80% under 100 times reduced intensity. This requires matching the voltages of the photovoltaic module and the battery circumventing maximum power point tracking. Single solar cells show efficiencies up to 10% under AM1.5 illumination and open circuit voltages, Voc, of 450-500mV. To match the battery’s voltage the miniaturised solar cells (~1mm2 area) are connected in series via wire bonding. The chemical sensor platform (mm2 area) is set up to detect hydrogen gas concentration in the low ppm range and over a broad temperature range using a low power sensing interface circuit. Using Telran TZ1053 radio to send one sample measurement of both temperature and H2 concentration every 15 seconds, the average and active power consumption for the SiNAPS mote are less than 350nW and 2.1 μW respectively. Low-power miniaturised chemical sensors of liquid analytes through microfluidic delivery to silicon nanowires are also presented. These components demonstrate the potential of further miniaturization and application of sensor nodes beyond the typical physical sensors, and are enabled by the nanowire materials platform.
Molecular layer doping: non-destructive doping of silicon and germanium
(IEEE, 2014-06) Long, Brenda; Verni, Giuseppe A.; O'Connell, John; Holmes, Justin D.; Shayesteh, Maryam; O'Connell, Dan; Duffy, Ray
This work describes a non-destructive method to introduce impurity atoms into silicon (Si) and germanium (Ge) using Molecular Layer Doping (MLD). Molecules containing dopant atoms (arsenic) were designed, synthesized and chemically bound in self-limiting monolayers to the semiconductor surface. Subsequent annealing enabled diffusion of the dopant atom into the substrate. Material characterization included assessment of surface analysis (AFM) and impurity and carrier concentrations (ECV). Record carrier concentration levels of arsenic (As) in Si (~5Ã 10^20 atoms/cm3) by diffusion doping have been achieved, and to the best of our knowledge this work is the first demonstration of doping Ge by MLD. Furthermore due to the ever increasing surface to bulk ratio of future devices (FinFets, MugFETs, nanowire-FETS) surface packing spacing requirements of MLD dopant molecules is becoming more relaxed. It is estimated that a molecular spacing of 2 nm and 3 nm is required to achieve doping concentration of 10^20 atoms/cm3 in a 5 nm wide fin and 5 nm diameter nanowire respectively. From a molecular perspective this is readily achievable.

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