Prof. Mahendra K. Sunkara Profile

Prof. Mahendra K. Sunkara

Professor of Chemical Engineering at Univ of Louisville

SPIE Involvement:

Author

Publications (4)

Proceedings Article | 15 September 2007 Paper

The role of surface states in a-axis GaN nanowires

Alan Chin, Tai Ahn, Hongwei Li, Sreeram Vaddiraju, Christopher Bardeen, Cun-Zheng Ning, Mahendra Sunkara

Proceedings Volume 6639, 663908 (2007) https://doi.org/10.1117/12.732222

KEYWORDS: Gallium nitride, Luminescence, Picosecond phenomena, Ultraviolet radiation, Gallium, Crystals, Glasses, Edge emitting semiconductor lasers, Nanowires, Oxidation

Read Abstract +

Proceedings Article | 3 March 2006 Paper

Direction dependent homoepitaxial growth and bandgap of GaN nanowires

Mahendra Sunkara, Hongwei Li, Alan Chin

Proceedings Volume 6121, 61210I (2006) https://doi.org/10.1117/12.658050

KEYWORDS: Gallium nitride, Gallium, Plasma, Crystals, Diffusion, Nitrogen, Quartz, Hydrogen, Atmospheric plasma, Nanowires

Read Abstract +

Proceedings Article | 29 December 2004 Paper

Carbon nanopipettes and microtubes for electrochemical sensing and microfluidics

Radhika Mani, Gopinath Bhimarasetti, Randall Lowe, Mahendra Sunkara

Proceedings Volume 5593, (2004) https://doi.org/10.1117/12.571363

KEYWORDS: Carbon, Gallium, Electrodes, Oxygen, Carbon nanotubes, Plasma, Nanostructures, Platinum, Nitrogen, Microfluidics

Read Abstract +

We present the synthesis of two novel morphologies for carbon tubular structures: Nanopipettes and Micropipes. The synthesis procedures for both these structures are both unique and different from each other and the conventional methods used for carbon nanotubes. Carbon nanopipettes, open at both ends, are made up of a central nanotube (~10-20 nm) surrounded by helical sheets of graphite. Thus nanopipettes have an outer conical structure, with a base size of about a micron, that narrows down to about 10-20 nm at the tip. Due to their unique morphology, the outer walls of the nanopipettes continuously expose edge planes of graphite, giving a very stable and reversible electrochemical response for detecting neurological compounds such as dopamine. The synthesis of carbon nanopipettes is based on high temperature nucleation and growth of carbon nanotubes under conditions of hydrogen etching during growth. Carbon micropipes, on the other hand, are tubular structures whose internal diameters range from a few nanometers to a few microns with a constant wall thickness of 10-20 nm. In addition to tuning the internal diameters, the conical angles of these structures could also be changed during synthesis. Due to their larger inner diameters and thin walls, both the straight and conical micro-tubular structures are suitable for microfluidic devices such as throttle valves, micro-reactors, and distribution channels. The synthesis of carbon micro-tubular structures is based on the wetting behavior of gallium with carbon during growth. The contact angle between gallium and the carbon wall determines the conical angle of the structure. By varying the contact angle, one can alter the conical angles from 400 to -150, and synthesize straight tubes using different N₂/O₂ dosing compositions. An 'n-step' dosing sequence at various stages of growth resulted in 'n-staged' morphologies for carbon micro-tubular structures such as funnels, tube-on-cone, Y-junctions and dumbbells.

Proceedings Article | 29 December 2004 Paper

Chemical design of inorganic nanowires, nanotubes and nanowire networks

Mahendra Sunkara, S. Vaddiraju, Gopinath Bhimarasetti, H. Chandrasekaran, H. Li, R. Bogale, T. Powers, R. Thurman

Proceedings Volume 5593, (2004) https://doi.org/10.1117/12.571424

KEYWORDS: Metals, Gallium, Oxides, Silicon, Tungsten, Hydrogen, Scanning electron microscopy, Oxygen, Plasma, Nanowires

Read Abstract +

View contact details

UPDATE YOUR PROFILE

Is this your profile? Update it now.

Sign into your SPIE.org account

Don’t have a profile and want one?

Create an account on SPIE.org

Keywords/Phrases

Search In:

Publication Years