Current research

I am currently a member of the Senior Professional Staff of Johns Hopkins University Applied Physics Laboratory working with RF-photonic systems.

Past research

Optoelectronic oscillators and photonic phase noise measurement systems

As a postdoctoral research associate at the University of Maryland Baltimore County I studied optoelectronic oscillators. Reduced spurious oscillating modes by 60 dB. Studied phase noise sources and minimization techniques. Improved ultra-low phase noise measurement system sensitivity to -140 dBc/Hz at 1 kHz. Automated data acquisition with LabVIEW. Wrote proposal for a $2 million research program. Advisor: Gary M. Carter

Real-time observation of oxidation kinetics at the bond level

Developed a technique for measuring real-time oxidation kinetics of (111) oriented silicon on a bond-by-bond basis using a combination of second-harmonic generation and spectroscopic ellipsometry. This technique can be used to study real-time chemical and structural changes in many materials. Advisor: Kenan Gundogdu

Epitaxial growth of zinc oxide by metal-organic chemical vapor deposition

Developed a process for epitaxial growth of dense two-dimensional zinc oxide via MOCVD. Filed four invention disclosures and two patent applications on this process. Used real-time spectroscopic ellipsometry for in-situ diagnostics and control. Responsible for all aspects of MOCVD system including setup, maintenance, hardware and software process control. Advisor: David E. Aspnes

Atomic scale theory of nonlinear optics

Performed spectroscopic optical second-harmonic-generation measurements on silicon with various dielectric overlayers using ultrafast Ti:Sapphire laser. Developed the anisotropic bond model of nonlinear optics. Dissertation title: "Anisotropic Bond Model of Nonlinear Optics and Applications to Silicon and Silicon-Dielectric Interfaces". Advisor: David E. Aspnes.

Papers

Field amplifications in surface-enhanced Raman scattering, E. J. Adles, D. E. Aspnes, and S. Franzen, 2011, manuscript in preparation.

Developing an epitaxial growth process for ZnO by MOCVD using real-time spectroscopic ellipsometry, Thin Solid Films, (2011) (in press).

Measurement and control of in-plane surface chemistry during the oxidation of H-terminated (111) Si, B. Gokce, E. J. Adles, K. Gundogdu, D. E. Aspnes, PNAS 107, 17503 (2010). [PDF] [DOI]

Spurious-mode suppression in optoelectronic oscillators, O. Okusaga, E. J. Adles, W. Zhou, C. Menyuk, G. Carter, E. Levy, M. Horowitz, Proceedings of 2010 IEEE International Frequency Control Symposium. [PDF] [DOI]

Loop-length dependent sources of phase noise in optoelectronic oscillators, E. J. Adles, A. Docherty, C. Menyuk, G. Carter, O. Okusaga, W. Zhou, E. Levy, A. David, M. Horowitz, Proceedings of 2010 IEEE International Frequency Control Symposium [PDF] [DOI]

Chemical-etch assisted growth of eptiaxial zinc-oxide, E. J. Adles, D. E. Aspnes, J. Vac. Sci. Tech. A, 28, 728 (2010). [PDF] [DOI]

The anisotropic bond model of nonlinear optics, E. J. Adles and D. E. Aspnes, Phys. Status Solidi A 205, 728 (2008). [PDF] [DOI]

Application of the anisotropic bond model to second-harmonic generation from amorphous media, E. J. Adles and D. E. Aspnes, Phys. Rev. B. 77, 165102 (2008). [PDF] [DOI]

Relative bulk and interface contributions to optical second-harmonic generation in silicon, H. J. Peng, E. J. Adles, J. F. T. Wang, and D. E. Aspnes, Phys. Rev. B 72, 205203 (2005). [PDF] [DOI]

Presentations

Use of real-time ellipsometry to understand and control the chemistry of ZnO growth by MOCVD, Int. Conf. Spectroscopic Ellipsometry, 2010 (invited)

Loop-length Dependent Phase Noise in Optoelectronic Oscillators, Int. Freq. Cont. Symp., June 2010.

Observation of Realtime Oxidation of Si(111) Surfaces using Second Harmonic Generation, AVS 56th International Symposium, San Jose, CA, November 2009.

Cyclic In-Situ Deposition and Etching for Growth of High-Quality Zinc Oxide by Metalorganic Chemical Vapor Deposition, AVS 56th International Symposium, San Jose, CA, November 2009.

Field Amplification in Surface-Enhanced Raman Scattering, AVS 56th International Symposium, San Jose, CA, November 2009.

Virtual Sources in OMCVD Growth of ZnO: The importance of real-time diagnostics for process development. 75th Annual Meeting of the Southeastern Section of APS, Raleigh, NC, October 2008.

Application of the Anisotropic Bond Model to a Single Bond Attached to a Sphere. 75th Annual Meeting of the Southeastern Section of APS, Raleigh, NC, October 2008.

Demonstration of mastery: The future of exams. Invited member of discussion panel, 2007 AAPT Summer Meeting, Greensboro, NC, July 2007.

Anisotropic bond model of nonlinear optics: Application to Si-dielectric interfaces. 4th International Conference on Spectroscopic Ellipsometry, Stockholm, Sweden, June 2007.

Origin of second-harmonic-generation from silicon nanoinclusions in glass. 2007 APS March Meeting, Denver, CO, March 2007.

Second-harmonic generation from Si nanocrystals: Field-gradient effects in the anisotropic bond model. 34th Conference on the Physics and Chemistry of Semiconductor Interfaces, Salt Lake City, UT, January 2007.

Isolation of bulk and surface contributions to second-harmonic generation in centro-symmetric silicon using the simplified bond-hyperpolarizability model (SBHM). 32nd Conference on the Physics and Chemistry of Semiconductor Interfaces, Bozeman, MT, January 2005.

Patents

Applications and disclosures

U.S. Provisional Application No. 61/230,414, July 31, 2009, Methods of forming zinc oxide layers by sublimating zinc particles in advance of zinc oxide deposition.

U.S. Provisional Application No. 61/166,082, April 2, 2009, Epitaxial growth of zinc oxide by metalorganic chemical vapor deposition.

Method for preparation of zinc oxide, NC State University, 2008.

Optical diagnostics for zinc oxide (ZnO) process development and control, NC State University, 2008.

Method and device for generating molecular zinc oxide, NC State University, 2008.

Method for chemical-etch assisted growth of epitaxial zinc oxide, NC State University, 2009.

Granted

7,213,967, May 8, 2007, Method and system for conservative evaluation and monitoring of thermal processing.

7,004,620, February 28, 2006, Method and system for conservative evaluation and monitoring of thermal processing.

6,776,523, August 17, 2004, Method and system for conservative evaluation and monitoring of thermal processing.

Service

President, Graduate Physics Student Association, North Carolina State University, 2003-2004

Administrator for Linux server and content management system for the Graduate Physics Student Association, North Carolina State University, 2003-2006.