Sarah Sambasivan | Suffolk County Community College (original) (raw)

Papers by Sarah Sambasivan

Langmuir, Mar 16, 2007

We measured the molecular order of poly(3-alkylthiophene) chains in thin films before and after m... more We measured the molecular order of poly(3-alkylthiophene) chains in thin films before and after melting through the combination of several polarized photon spectroscopies: infrared (IR) absorption, variable angle spectroscopic ellipsometry (SE), and near-edge X-ray absorption fine structure (NEXAFS). The data from the various techniques can be uniformly treated in the context of the dielectric constant tensor for the film. The combined spectroscopies allow determination of the orientation distribution of the main-chain axis (SE and IR), the conjugated π system normal (NEXAFS), and the side-chain axis (IR). We find significant improvement in the backbone order of the films after recrystallization of the material at temperatures just below the melting temperature. Less aggressive thermal treatments are less effective. IR studies show that the changes in backbone structure occur without significant alteration of the structure of the alkyl side chains. The data indicate that the side chains exhibit significant disorder for all films regardless of the thermal history of the sample.

Proceedings of SPIE, Jun 11, 2003

We utilize near edge X-ray absorption fine structure spectroscopy (NEXAFS) to provide detailed ch... more We utilize near edge X-ray absorption fine structure spectroscopy (NEXAFS) to provide detailed chemical insight into two interfacial problems facing sub-100 nm patterning. First, chemically amplified photo-resists are sensitive to surface phenomenon, which causes deviations in the pattern profile near the interface. Striking examples include T-topping, closure, footing, and undercutting. NEXAFS was used to examine surface segregation of a photo-acid generator at the resist/air interface and to illustrate that the surface extent of deprotection in a model resist film can be different than the bulk extent of deprotection. Second, line edge roughness becomes increasingly critical with shrinking patterns, and may be intimately related to the line edge deprotection profile. A NEXAFS technique to surface depth profile for compositional gradients is described with the potential to provide chemical information about the resist line edge.

$Research paper thumbnail of Hole State Density of La1-xSrxCoO^d3-{Δ} (0{less then or equal to}x{less then or equal to}0.5) Across the Insulator/Metal Phase Boundary | NIST$

Small, 2006

We have demonstrated near-edge X-ray absorption fine structure (NEXAFS) spectroscopy as a particu... more We have demonstrated near-edge X-ray absorption fine structure (NEXAFS) spectroscopy as a particularly useful and effective technique for simultaneously probing the surface chemistry, surface molecular orientation, degree of order, and electronic structure of carbon nanotubes and related nanomaterials. Specifically, we employ NEXAFS in the study of single-walled carbon nanotube and multi-walled carbon nanotube powders, films, and arrays, as well as of boron nitride nanotubes. We have focused on the advantages of NEXAFS as an exciting, complementary tool to conventional microscopy and spectroscopy for providing chemical and structural information about nanoscale samples.

John Wiley & Sons, Inc. eBooks, Mar 28, 2008

Biomaterials, Jan 25, 2000

With the increasing drive towards smaller feature sizes in integrated circuits and the consequent... more With the increasing drive towards smaller feature sizes in integrated circuits and the consequent use of shorter exposure wavelengths, the imaging resist layer and underlying bottom anti-reflective coating (BARC) layer are becoming thinner. At this scale, the performance of chemically amplified resists can be adversely affected by the BARC-resist interfacial interactions. These interactions can cause distortion of resist profiles and lead to footing, undercut, or pattern collapse. -BARC components can immensely influence the deprotection and dissolution properties of the resist. A thorough understanding of the physico-chemical interactions at these interfaces is essential to design and develop new material platforms with minimal adverse interactions and maximum compatibility between BARC and resist. Results are reported from studies of (A) surface versus bulk chemistry of BARC materials as a function of cure temperature, (B) the dependence of the thickness and composition of the res...

CRC Press eBooks, Jun 4, 2008

... 33. Delongchamp, D., Sambasivan, S., Fischer, DA, Lin, EK, Chang, P., Murphy, AR, Fréchet, JM... more ... 33. Delongchamp, D., Sambasivan, S., Fischer, DA, Lin, EK, Chang, P., Murphy, AR, Fréchet, JMJ, and Subramanian, V. 2005. Adv. ... 17: 2334. 34. Genzer, J., Efimenko, K., and Fischer, DA 2002. ... Srinivasan, G., Pursch, M., Sander, LC, and Muller, KH 2004. Langmuir 20: 1746. ...

EDULEARN19 Proceedings, 2019

Submitted for the MAR05 Meeting of The American Physical Society Correlating structure developmen... more Submitted for the MAR05 Meeting of The American Physical Society Correlating structure development to performance enhancement in organic semiconductor films ERIC LIN, DEAN DELONGCHAMP, SHARADHA SAMBASIVAN, DANIEL FISCHER, National Institute of Standards and Technology-Measuring the structural development of organic semiconductor films and correlating it to the electrical characteristics of organic field effect transistors (OFETs) is a critical steppingstone to commercialization. Synchrotron-based Near-Edge X-ray Absorption Fine Structure (NEXAFS) spectroscopy is a powerful tool that can non-destructively reveal the structure and chemistry of thin organic films. The density of bonds involving carbon, nitrogen, oxygen, and fluorine can be quantified, a composition depth profile can be developed for the top (2-10) nm of the film, and bond orientation can be determined. We employ NEXAFS to investigate chemistry, molecular orientation, and defects in thin organic semiconductor films. These quantities are then correlated to OFET performance. Examples will include classical model systems such as pentacene and regioregular poly(3-hexylthiophene), as well as new molecules. Thermal processing-induced increases in molecular orientation will be described. Structure and performance enhancement by hydrophobic substrate modification will be discussed. Finally, the role of the semiconductor chemical structure itself will be considered. NEXAFS provides excellent correlation of processing to structure to performance, illuminating fruitful development vectors for next-generation materials.

ACS Symposium Series, 2004

Control of the shape, critical dimension (CD), and roughness is critical for the fabrication of s... more Control of the shape, critical dimension (CD), and roughness is critical for the fabrication of sub 100 nm features, where the CD and roughness budget are approaching the molecular dimension of the resist polymers 1. Here we utilize near edge X-ray absorption fine structure (NEXAFS) to provide detailed chemical insight into two interfacial problems facing sub-100 nm patterning. First, chemically amplified photoresists are prone to surface phenomenon, which causes deviations in the pattern profile near the interface. Striking examples include T-topping, closure, footing, and undercutting. NEXAFS was used to illustrate that the surface extent of deprotection in a model resist film can be different than the bulk deprotection. Second, line edge roughness becomes increasingly critical with shrinking patterns, and may be intimately related to the line edge deprotection profile. A NEXAFS technique to surface depth profile for compositional gradients is described with the potential to provide detailed chemical information about the resist line edge.

Surfactants in Tribology, 2008

Journal of the American Ceramic Society, 2005

... Al2O3–Y2O3 System Tai-Il Mah,*,† Kristin A. Keller,*,† Sankar Sambasivan,*,‡ and Ronald J. Ke... more ... Al2O3–Y2O3 System Tai-Il Mah,*,† Kristin A. Keller,*,† Sankar Sambasivan,*,‡ and Ronald J. Kerans* ... 2T. Mah, K. Keller, TA Parthasarathy, and J. Guth, “Fugitive Interface Coating in Oxide–Oxide Composites: A Viability Study,” Ceram. Eng. Sci. ...