@misc{bocian_lindsey_liu_yesseri_misra_zhao_li_surthi_loewe_2007, title={High temperature attachment of organic molecules to substrates}, volume={7,223,628}, number={2007 May 29}, publisher={Washington, DC: U.S. Patent and Trademark Office}, author={Bocian, D. F. and Lindsey, J. and Liu, Z. and Yesseri, A. A. and Misra, V. and Zhao, Q. and Li, Q. and Surthi, S. and Loewe, R. S.}, year={2007} }
 @article{gowda_mathur_li_surthi_misra_2006, title={Hybrid silicon/molecular FETs: A study of the interaction of redox-active molecules with silicon MOSFETs}, volume={5}, ISSN={["1941-0085"]}, DOI={10.1109/TNANO.2006.874046}, abstractNote={Redox-active molecular monolayers were incorporated in silicon MOSFETs to obtain hybrid silicon/molecular FETs. Cyclic voltammetry and FET characterization techniques were used to study the properties of these hybrid devices. The redox-active molecules have tunable charge states, which are quantized at room temperature and can be accessed at relatively low voltages. The discrete molecular states were manifested in the drain current and threshold voltage characteristics of the device, confirming the presence of distinct energy levels within the molecules at room temperature. This study demonstrates the modulation of Si-MOSFETs' drain currents via redox-active molecular monolayers. The single-electron functionality provided by the redox-active molecules is ultimately scalable to molecular dimensions, and this approach can be extended to nanoscale field-effect devices including those based on carbon nanotubes. The molecular states coupled with CMOS devices can be utilized for low-voltage, multiple-state memory and logic applications and can extend the impact of silicon-based technologies.}, number={3}, journal={IEEE TRANSACTIONS ON NANOTECHNOLOGY}, author={Gowda, Srivardhan and Mathur, Guru and Li, Qiliang and Surthi, Shyam and Misra, Veena}, year={2006}, month={May}, pages={258–264} }
 @article{gowda_mathur_li_surthi_misra_2005, title={Approach for investigating lateral conduction in self-assembled monolayers}, volume={87}, ISSN={["1077-3118"]}, DOI={10.1063/1.2152112}, abstractNote={Lateral conductivity within a monolayer is a key factor in the implementation of emerging dense molecular memory devices since it determines the degree of cross talk between cells. Lateral interactions within a monolayer could also lead to loss of charge through defective sites. Existing characterization techniques are limited to probing the electrical communication between molecules and attached electrodes. In this paper we demonstrate a test structure consisting of n type and p type doped silicon islands to isolate vertical conduction from lateral conduction. This structure is a useful characterization tool for tailoring the intrinsic properties of the molecules for information storage.}, number={26}, journal={APPLIED PHYSICS LETTERS}, author={Gowda, S and Mathur, G and Li, Q and Surthi, S and Misra, V}, year={2005}, month={Dec} }
 @article{mathur_gowda_li_surthi_zhao_misra_2005, title={Properties of functionalized redox-active monolayers on thin silicon dioxide - A study of the. dependence of retention time on oxide thickness}, volume={4}, ISSN={["1941-0085"]}, DOI={10.1109/TNANO.2004.842056}, abstractNote={Self-assembled monolayers of redox-active molecules were formed on varying thickness of silicon dioxide (SiO/sub 2/). Cyclic voltammetry (CyV) and impedance spectroscopy (capacitance-voltage and conductance-voltage) techniques were used to characterize these structures. The charge retention properties of these molecule-oxide-silicon capacitor structures were studied by applying oxidizing voltages in two successive CyV scans without applying a reducing voltage in between the two scans. A variation of this technique, wherein a reducing voltage is applied in the second scan, was also employed. The wait time between the two scans was varied from 0 to 300 s. The number of molecules oxidized (or reduced) in the second scan increased (or decreased) with increasing wait time, which is attributed to increasing charge leakage with increasing time. The retention properties of these structures were studied and correlated to increasing oxide thickness. It was observed that the retention times increased with increasing oxide thickness if the voltage applied during the wait time was in between the oxidation and reduction peak voltages. The molecular scalability and ability to tune the retention times by varying the oxide thickness make these Si/molecular hybrid devices attractive candidates for next-generation memory applications.}, number={2}, journal={IEEE TRANSACTIONS ON NANOTECHNOLOGY}, author={Mathur, G and Gowda, S and Li, QL and Surthi, S and Zhao, Q and Misra, V}, year={2005}, month={Mar}, pages={278–283} }
 @article{zhao_luo_surthi_li_mathur_gowda_larson_johnson_misra_2005, title={Redox-active monolayers on nano-scale silicon electrodes}, volume={16}, ISSN={["1361-6528"]}, DOI={10.1088/0957-4484/16/2/013}, abstractNote={Uniform arrays of nano-scale electrolyte–molecule–silicon capacitors have been successfully fabricated. This was done by a combination of reactive ion etch and a selective wet etch through an anodic aluminium oxide mask to form nano-holes in silicon oxide/silicon nitride insulator layers on silicon. Self-assembled monolayers of 4-ferrocenylbenzyl alcohol were then attached to the exposed silicon surfaces at the bottom of the nano-holes. Characterization by conventional capacitance and conductance techniques showed very high capacitance and conductance peaks near −0.6 V, that were attributed to the charging and discharging of electrons into and from discrete levels in the monolayer owing to the presence of the redox-active ferrocenes.}, number={2}, journal={NANOTECHNOLOGY}, author={Zhao, Q and Luo, Y and Surthi, S and Li, QL and Mathur, G and Gowda, S and Larson, PR and Johnson, MB and Misra, V}, year={2005}, month={Feb}, pages={257–261} }
 @article{li_mathur_gowda_surthi_zhao_yu_lindsey_bocian_misra_2004, title={Multibit memory using self-assembly of mixed ferrocene/porphyrin monolayers on silicon}, volume={16}, ISSN={["1521-4095"]}, DOI={10.1002/adma.200305680}, abstractNote={An alternative strategy for achieving multi‐bit functionality, which uses mixed self‐assembled monolayers of a benzyl alcohol‐tethered ferrocene (Fc‐BzOH) and a benzyl alcohol‐tethered porphyrin (Por‐BzOH) on silicon surfaces to achieve a four‐state (2‐bit) memory element, is presented. The four states include the neutral state and three distinct cationic states obtained upon oxidation of Fc‐BzOH (monopositive) and Por‐BzOH (monopositive, dipositive) molecules. Conventional cyclic voltammetry, capacitance, and conductance methods have been used to characterize the mixed monolayer.}, number={2}, journal={ADVANCED MATERIALS}, author={Li, QL and Mathur, G and Gowda, S and Surthi, S and Zhao, Q and Yu, LH and Lindsey, JS and Bocian, DF and Misra, V}, year={2004}, month={Jan}, pages={133-+} }
 @article{li_surthi_mathur_gowda_zhao_sorenson_tenent_muthukumaran_lindsey_misra_2004, title={Multiple-bit storage properties of porphyrin monolayers on SiO2}, volume={85}, ISSN={["1077-3118"]}, DOI={10.1063/1.1782254}, abstractNote={Hybrid molecule-silicon capacitors have been fabricated by the self-assembly of a monolayer of porphyrin molecules on a silicon oxide surface. The porphyrin employed [5-(4-dihydroxyphosphorylphenyl)-10,15,20-trimesitylporphinatozinc(II)] attaches to silicon oxide via a phosphonate linkage. Cyclic voltammetry current and capacitance/conductance measurements have been used to characterize the capacitors. The presence of multiple distinct peaks in current density and capacitance/conductance measurements are associated with oxidation and reduction of the molecular monolayer. The charge-storage states of the capacitor indicate applicability for use in multiple-bit memory devices.}, number={10}, journal={APPLIED PHYSICS LETTERS}, author={Li, QL and Surthi, S and Mathur, G and Gowda, S and Zhao, Q and Sorenson, TA and Tenent, RC and Muthukumaran, K and Lindsey, JS and Misra, V}, year={2004}, month={Sep}, pages={1829–1831} }
 @article{muthukumaran_loewe_ambroise_tamaru_li_mathur_bocian_misra_lindsey_2004, title={Porphyrins bearing arylphosphonic acid tethers for attachment to oxide surfaces}, volume={69}, ISSN={["0022-3263"]}, DOI={10.1021/jo034945l}, abstractNote={Synthetic molecules bearing phosphonic acid groups can be readily attached to oxide surfaces. As part of a program in molecular-based information storage, we have developed routes for the synthesis of diverse porphyrinic compounds bearing phenylphosphonic acid tethers. The routes enable (1) incorporation of masked phosphonic acid groups in precursors for use in the rational synthesis of porphyrinic compounds and (2) derivatization of porphyrins with masked phosphonic acid groups. The precursors include dipyrromethanes, monoacyldipyrromethanes, and diacyldipyrromethanes. The tert-butyl group has been used to mask the dihydroxyphosphoryl substituent. The di-tert-butyloxyphosphoryl unit is stable to the range of conditions employed in syntheses of porphyrins and multiporphyrin arrays yet can be deprotected under mild conditions (TMS-Cl/TEA or TMS-Br/TEA in refluxing CHCl(3)) that do not cause demetalation of zinc or magnesium porphyrins. The porphyrinic compounds that have been prepared include (1) A(3)B-, trans-AB(2)C-, and ABCD-porphyrins that bear a single phenylphosphonic acid group, (2) a trans-A(2)B(2)-porphyrin bearing two phenylphosphonic acid groups, (3) a chlorin that bears a single phenylphosphonic acid group, and (4) a porphyrin dyad bearing a single phenylphosphonic acid group. For selected porphyrin-phosphonic acids, the electrochemical characteristics have been investigated for molecules tethered to SiO(2) surfaces grown on doped Si. The voltammetric behavior indicates that the porphyrin-phosphonic acids form robust, electrically well-behaved monolayers on the oxide surface.}, number={5}, journal={JOURNAL OF ORGANIC CHEMISTRY}, author={Muthukumaran, K and Loewe, RS and Ambroise, A and Tamaru, SI and Li, QL and Mathur, G and Bocian, DF and Misra, V and Lindsey, JS}, year={2004}, month={Mar}, pages={1444–1452} }
 @article{loewe_ambroise_muthukumaran_padmaja_lysenko_mathur_li_bocian_misra_lindsey_2004, title={Porphyrins bearing mono or tripodal benzylphosphonic acid tethers for attachment to oxide surfaces}, volume={69}, ISSN={["1520-6904"]}, DOI={10.1021/jo034946d}, abstractNote={The ability to attach redox-active molecules to oxide surfaces in controlled architectures (distance, orientation, packing density) is essential for the design of a variety of molecular-based information storage devices. We describe the synthesis of a series of redox-active molecules wherein each molecule bears a benzylphosphonic acid tether. The redox-active molecules include zinc porphyrins, a cobalt porphyrin, and a ferrocene-zinc porphyrin. An analogous tripodal tether has been prepared that is based on a tris[4-(dihydroxyphosphorylmethyl)phenyl]-derivatized methane. A zinc porphyrin is linked to the methane vertex by a 1,4-phenylene unit. The tripodal systems are designed to improve monolayer stability and ensure vertical orientation of the redox-active porphyrin on the electroactive surface. For comparison purposes, a zinc porphyrin bearing a hexylphosphonic acid tether also has been prepared. The synthetic approaches for introduction of the phosphonic acid group include derivatization of a bromoalkyl porphyrin or use of a dimethyl or diethyl phosphonate substituted precursor in a porphyrin-forming reaction. The latter approach makes use of dipyrromethane building blocks bearing mono or tripodal dialkyl phosphonate groups. The zinc porphyrin-tripodal compound bearing benzylphosphonic acid legs tethered to a SiO(2) surface (grown on doped Si) was electrically well-behaved and exhibited characteristic porphyrin oxidation/reduction waves. Collectively, a variety of porphyrinic molecules can now be prepared with tethers of different length, composition, and structure (mono or tripodal) for studies of molecular-based information storage on oxide surfaces.}, number={5}, journal={JOURNAL OF ORGANIC CHEMISTRY}, author={Loewe, RS and Ambroise, A and Muthukumaran, K and Padmaja, K and Lysenko, AB and Mathur, G and Li, QL and Bocian, DF and Misra, V and Lindsey, JS}, year={2004}, month={Mar}, pages={1453–1460} }
 @article{liu_yasseri_loewe_lysenko_malinovskii_zhao_surthi_li_misra_lindsey_et al._2004, title={Synthesis of porphyrins bearing hydrocarbon tethers and facile covalent attachment to Si(100)}, volume={69}, ISSN={["0022-3263"]}, DOI={10.1021/jo049439q}, abstractNote={The use of redox-active molecules as the active storage elements in memory chips requires the ability to attach the molecules to an electroactive surface in a reliable and robust manner. To explore the use of porphyrins tethered to silicon via carbosilane linkages, 17 porphyrins have been synthesized. Fourteen porphyrins bear a tether at a single meso site, and three porphyrins bear functional groups at two beta sites for possible two-point attachment. Two high-temperature processing methods (400 degrees C under inert atmosphere) have been developed for rapid (minutes), facile covalent attachment to Si platforms. The high-temperature processing conditions afford attachment either by direct deposition of a dilute solution (1 microM-1 mM) of the porphyrin sample onto the Si substrate or sublimation of a neat sample onto the Si substrate. The availability of this diverse collection of porphyrins enables an in-depth examination of the effects of the tether (length, composition, terminal functional group, number of tethers) and steric bulk of nonlinking substituents on the information-storage properties of the porphyrin monolayers obtained upon attachment to silicon. Attachment proceeds readily with a wide variety of hydrocarbon tethers, including 2-(trimethylsilyl)ethynyl, vinyl, allyl, or 3-butenyl directly appended to the porphyrin and iodo, bromomethyl, 2-(trimethylsilyl)ethynyl, ethynyl, vinyl, or allyl appended to the 4-position of a meso-phenyl ring. No attachment occurs with substituents such as phenyl, p-tolyl, mesityl, or ethyl. Collectively, the studies show that the high-temperature attachment procedure (1) has broad scope encompassing diverse functional groups, (2) tolerates a variety of arene substituents, and (3) does not afford indiscriminate attachment. The high-temperature processing conditions are ideally suited for use in fabrication of hybrid molecular/semiconductor circuitry.}, number={17}, journal={JOURNAL OF ORGANIC CHEMISTRY}, author={Liu, ZM and Yasseri, AA and Loewe, RS and Lysenko, AB and Malinovskii, VL and Zhao, Q and Surthi, S and Li, QL and Misra, V and Lindsey, JS and et al.}, year={2004}, month={Aug}, pages={5568–5577} }
 @article{li_surthi_mathur_gowda_misra_sorenson_tenent_kuhr_tamaru_lindsey_et al._2003, title={Electrical characterization of redox-active molecular monolayers on SiO2 for memory applications}, volume={83}, ISSN={["0003-6951"]}, DOI={10.1063/1.1584088}, abstractNote={Hybrid silicon capacitors have been successfully fabricated by attaching monolayers of redox-active molecules via self-assembly to ultrathin silicon dioxide layers. Capacitance, conductance, and cyclic voltammetric measurements have been used to characterize these capacitors. The presence of distinct capacitance and conductance peaks associated with oxidation and reduction of the monolayers at low gate voltages indicates discrete electron storage states for these capacitors, suggesting their feasibility in memory devices. The inherent molecular scalability and low-power operation coupled with existing silicon technology support the approach of hybrid molecule-silicon devices as a strong candidate for next generation electronic devices.}, number={1}, journal={APPLIED PHYSICS LETTERS}, author={Li, QL and Surthi, S and Mathur, G and Gowda, S and Misra, V and Sorenson, TA and Tenent, RC and Kuhr, WG and Tamaru, S and Lindsey, JS and et al.}, year={2003}, month={Jul}, pages={198–200} }
 @article{li_mathur_homsi_surthi_misra_malinovskii_schweikart_yu_lindsey_liu_et al._2002, title={Capacitance and conductance characterization of ferrocene-containing self-assembled monolayers on silicon surfaces for memory applications}, volume={81}, ISSN={["0003-6951"]}, DOI={10.1063/1.1500781}, abstractNote={Self-assembled monolayers of 4-ferrocenylbenzyl alcohol attached to silicon provided the basis for electrolyte-molecule-silicon capacitors. Characterization by conventional capacitance and conductance techniques showed very high capacitance and conductance peaks near ∼0.6 V associated with charging and discharging of electrons into and from discrete levels in the monolayer owing to the presence of the redox-active ferrocenes. The reversible charge trapping of these molecules suggest their potential application in memory devices. Due to the molecular scalability and low-power operation, molecular-silicon hybrid devices may be strong candidates for next-generation electronic devices.}, number={8}, journal={APPLIED PHYSICS LETTERS}, author={Li, QL and Mathur, G and Homsi, M and Surthi, S and Misra, V and Malinovskii, V and Schweikart, KH and Yu, LH and Lindsey, JS and Liu, ZM and et al.}, year={2002}, month={Aug}, pages={1494–1496} }