Boston University

Optical Characterization and Nanophotonics Laboratory

Home

About

People

Papers

Research

Facilities

Alumni

Quantum Dot Spectroscopy

Members: M. Selim Ünlü

 

Alumni: Roger Chen, Bennett B. Goldberg, Stephen Bradley Ippolito, Fatih Hakan Koklu, Zhiheng Liu, Yuliya Miretskaya, Hans D. Robinson, Anthony Nickolas Vamivakas, Richard D. Younger, Abdulkadir Yurt

 

Experimental and theorectical investigations of the physics of self-assembled quantum dots (SADs) have focused largely on the nature of the individual dots, independent of their surroundings. However, the coupling of dots to each other, an external microcavity or nearby localized states is an important area of investigation, critical to issues of coherence and quantum information processing. For example, it has been found that the carriers may tunnel through the potential barrier of one QD to another QD via the localized states of the wetting layer(WL). We employ scanning SIL-confocal microscopy combined with time resolved photoluminescence(TRPL) spectroscopy to study small ensembles as well as individiual InGaAs/GaAs SADs. Due to high throughput of our experimental set-up we were able to observe state filling of individual dots. We explored the interaction between QDs and WL as well as the dynamics of the interband radiative recombination and intersublevel thermalization by determining the lifetimes of carriers in QDs and WL and then deduce the mechanism for carrier capture in the QDs.To achieve higher spatial resolution so that we can excite just a few quantum dots and investigate their individual behavior and interactions, we have developed a new subsurface solid immersion microscopy technique that uses the substrate as part of a 3.0 numerical aperture lens, providing ~100nm resolution and thus isolating several dots with very high throughput.

Publications

A. N. Vamivakas, A. Yurt, T. Muller, F. H. Koklu, M. S. Ünlü, and M. Atature, "Coherent light scattering from a buried dipole in a high-aperture optical system ," New Journal of Physics, Vol. 13, No. 053056 , May 2011

F. H. Koklu, A. N. Vamivakas, B. B. Goldberg, and M. S. Ünlü, "Tailoring the Local Environment of Quantum Dots for Enhanced Collection Efficiency," Proceedings of IEEE Lasers and Electro-Optics Society 2008 Annual Meeting, 9 November 2008

A. N. Vamivakas, S. B. Ippolito, A. K. Swan, M. S. Ünlü, M. Dogan, E. R. Behringer, and B. B. Goldberg, "Phase-sensitive detection of dipole radiation in a fiber-based high numerical aperture optical system ," Optics Letters, Vol. 32, No. 8, 15 April 2007, pp. 970-972

A. N. Vamivakas, Z. Liu, S. B. Ippolito, R. P. Mirin, B. B. Goldberg, and M. S. Ünlü, "High Resolution and High Collection Efficiency of Single Quantum Dots," Materials Research Society Proceedings Fall 2005, November 2005

M. S. Ünlü, A. N. Vamivakas, S. B. Ippolito, and B. B. Goldberg, "Numerical aperture increasing lens microscopy for quantum dot and integrated circuit imaging," European Optical Society Topical Meeting: Optical Microsystems, September 2005

Z. Liu, B. B. Goldberg, S. B. Ippolito, A. N. Vamivakas, M. S. Ünlü, and R. P. Mirin, "High resolution, high collection efficiency in numerical aperture increasing lens microscopy of individual quantum dots," Applied Physics Letters, Vol. 87, August 2005, pp. 071905

A. N. Vamivakas, Z. Liu, S. B. Ippolito, R. P. Mirin, B. B. Goldberg, and M. S. Ünlü, "Numerical Aperture Increasing Lens Microscopy for High Resolution and High Collection Efficiency Spectroscopy of Single Quantum Dots," Proceedings of CLEO/QELS 2005, May 2005

B. B. Goldberg, A. K. Swan, L. Moiseev, M. Dogan, W. C. Karl, B. J. Davis, C. R. Cantor, S. B. Ippolito, S. A. Thorne, M. G. Eraslan, Z. Liu, M. B. Goldberg, and Y. Leblebici, "Seeing inside chips and cells: High-resolution subsurface imaging of integrated circuits, quantum dots and subcellular structures," Proceedings of CLEO/QELS 2004, May 2004

M. S. Ünlü, M. G. Eraslan, Z. Liu, A. N. Vamivakas, S. A. Thorne, S. B. Ippolito, and B. B. Goldberg, "Application of Solid Immersion Lens Techniques to High-Resolution Subsurface Microscopy and Thermal Imaging," The 227th ACS National Meeting, March/April 2004

M. S. Ünlü, S. B. Ippolito, Z. Liu, B. B. Goldberg, and L. Novotny, "Immersion Lens Microscopy of Photonic Nano-structures and Quantum Dots," Materials Research Society Proceedings Fall 2002, December 2002

B. B. Goldberg, S. B. Ippolito, L. Novotny, Z. Liu, and M. S. Ünlü, "Immersion Lens Microscopy of Photonic Nanostructures and Quantum Dots," IEEE Journal of Selected Topics in Quantum Electronics, Vol. 8, September/October 2002, pp. 1051 -1059

B. B. Goldberg, Z. Liu, S. B. Ippolito, H. D. Robinson, and M. S. Ünlü, "Time-resolved spectroscopy of individual quantum dots," Proceedings of SPIE: Ultrafast Phenomena in Semiconductors VI, January 2002

H. D. Robinson, B. B. Goldberg, and J. L. Merz, "Observation of excitation transfer among neighboring quantum dots," Physical Review B, Vol. 64, 25 July 2001, pp. 075308

H. D. Robinson, and B. B. Goldberg, "Light induced spectral diffusion in single self-assembled quantum dots," Physical Review B, Vol. 61, No. 8, February 2000, pp. R5086

H. D. Robinson, and B. B. Goldberg, "Interdot carrier transfer and spectral diffusion: Consequences of wetting layer potential fluctuations in self-assembled quantum dots," Physica E, Vol. 6, No. 1-4, February 2000, pp. 444

H. D. Robinson, B. B. Goldberg, and J. L. Merz, "Lateral coupling of self-assembled quantum dots studied by near-field spectroscopy," Materials Research Society Proceedings Spring 1999, Vol. 571, 5-9 April 1999, pp. 89-94

H. D. Robinson, M. G. Müller, B. B. Goldberg, and J. L. Merz, "Local optical spectroscopy of self-assembled quantum dots using a near-field optical fiber probe to induce a localized strain-field," Applied Physics Letters, Vol. 72, No. 17, 27 April 1998, pp. 2081-2083


© 2007 Trustees of Boston University. All rights reserved.  |  Last modified April 16, 2007 at 12:00 AM EDT