Excitation in quantum dots is an important phenomenon. Realizing the importance we investigate the excitation behavior of a repulsive impurity-doped quantum dot induced by simultaneous oscillations of impurity potential and spatial stretch of impurity domain. The impurity potential has been assumed to have a Gaussian nature. The ratio of two oscillations ( ) has been exploited to understand the nature of excitation rate. Indeed it has been found that the said ratio could fabricate the excitation in a remarkable way. The present study also indicates attainment of stabilization in the excitation rate as soon as η surpasses a threshold value regardless of the dopant location. However, within the stabilization zone we also observe maximization in the excitation rate at some typical location of dopant incorporation. The critical analysis of pertinent impurity parameters provides important perception about the physics behind the excitation process. 1. Introduction Nowadays we frequently encounter a plethora of theoretical and experimental researches on impurity states in low-dimensional heterostructures [1]. The advent of so-called low-dimensional structures such as quantum dots (QD) has considerably accelerated the technology-driven demand of miniaturization of semiconductor devices. The quantized properties of quantum dots doped with impurity have generated new perspectives and subtleties in the field of applied physics. This happens because of the interplay between various confinement sources with impurity potentials [2]. Out of various kinds of investigations on impurity doping, control of optoelectronic properties emerges as the central theme [3–15]. Naturally, we find a vast literature comprising of good theoretical studies on impurity states [16–21]. Added to this, there are also some excellent experimental works which include the mechanism and control of dopant incorporation [22, 23]. Driven by the emergence of novel experimental and theoretical techniques along with the existing ones, the research on carrier dynamics in nanodevices has become a ubiquitous field. The internal transitions between impurity-induced states in a QD led to research on carrier dynamics [8, 24]. These transitions depend on the spatial restriction imposed by the impurity. A minute survey of the above dynamical features directs us to explore excitation of electrons strongly confined in QD’s. Analysis on this aspect deems importance since it offers us model systems for use in optoelectronic devices and as lasers. In connection with the technological applications, excitation in
References
[1]
P. M. Koenraad and M. E. Flatté, “Single dopants in semiconductors,” Nature Materials, vol. 10, no. 2, pp. 91–100, 2011.
[2]
J. L. Movilla and J. Planelles, “Off-centering of hydrogenic impurities in quantum dots,” Physical Review B, vol. 71, Article ID 075319, 7 pages, 2005.
[3]
C. P. Poole Jr. and F. J. Owens, Introduction to Nanotechnology, John Wiley & Sons, New York, NY, USA, 2003.
[4]
M. J. Kelly, Low-Dimensional Semiconductors, Oxford University Press, Oxford, UK, 1995.
[5]
W. Xie, “Nonlinear optical properties of an off-center donor in a quantum dot under applied magnetic field,” Solid State Communications, vol. 151, no. 7, pp. 545–549, 2011.
[6]
W. Xie, “Impurity effects on optical property of a spherical quantum dot in the presence of an electric field,” Physica B, vol. 405, no. 16, pp. 3436–3440, 2010.
[7]
R. Khordad, “Diamagnetic susceptibility of hydrogenic donor impurity in a V-groove quantum wire,” European Physical Journal B, vol. 78, no. 3, pp. 399–403, 2010.
[8]
C. A. Duque, N. Porras-Montenegro, Z. Barticevic, M. Pacheco, and L. E. Oliveira, “Effects of applied magnetic fields and hydrostatic pressure on the optical transitions in self-assembled InAs/GaAs quantum dots,” Journal of Physics Condensed Matter, vol. 18, no. 6, pp. 1877–1884, 2006.
[9]
Y. Yakar, B. ？akír, and A. ？zmen, “Calculation of linear and nonlinear optical absorption coefficients of a spherical quantum dot with parabolic potential,” Optics Communications, vol. 283, no. 9, pp. 1795–1800, 2010.
[10]
A. J. Peter, “Polarizabilities of shallow donors in spherical quantum dots with parabolic confinement,” Physics Letters A, vol. 355, no. 1, pp. 59–62, 2006.
[11]
K. M. Kumar, A. J. Peter, and C. W. Lee, “Optical properties of a hydrogenic impurity in a confined spherical quantum dot,” Superlattices and Microstructures, vol. 51, no. 1, pp. 184–193, 2012.
[12]
B. ？akir, Y. Yakar, A. ？zmen, M. ？. Sezer, and M. ？ahin, “Linear and nonlinear optical absorption coefficients and binding energy of a spherical quantum dot,” Superlattices and Microstructures, vol. 47, no. 4, pp. 556–566, 2010.
[13]
S. Baskoutas, E. Paspalakis, and A. F. Terzis, “Electronic structure and nonlinear optical rectification in a quantum dot: effects of impurities and external electric field,” Journal of Physics Condensed Matter, vol. 19, no. 39, Article ID 395024, 9 pages, 2007.
[14]
I. Karabulut and S. Baskoutas, “Second and third harmonic generation susceptibilities of spherical quantum dots: effects of impurities, electric field and size,” Journal of Computational and Theoretical Nanoscience, vol. 6, no. 1, pp. 153–156, 2009.
[15]
I. Karabulut and S. Baskoutas, “Linear and nonlinear optical absorption coefficients and refractive index changes in spherical quantum dots: effects of impurities, electric field, size, and optical intensity,” Journal of Applied Physics, vol. 103, Article ID 073512, 5 pages, 2008.
[16]
B. Gulveren, ü. Atav, M. Sahin, and M. Tomak, “A parabolic quantum dot with N electrons and an impurity,” Physica E, vol. 30, pp. 143–149, 2005.
[17]
E. R？s？nen, J. K？nemann, R. J. Haug, M. J. Puska, and R. M. Nieminen, “Impurity effects in quantum dots: toward quantitative modeling,” Physical Review B, vol. 70, no. 11, Article ID 115308, 6 pages, 2004.
[18]
M. Aichinger, S. A. Chin, E. Krotscheck, and E. R？s？nen, “Effects of geometry and impurities on quantum rings in magnetic fields,” Physical Review B, vol. 73, no. 19, Article ID 195310, 8 pages, 2006.
[19]
S. Baskoutas and A. F. Terzis, “Binding energy of hydrogenic impurity states in an inverse parabolic quantum well under static external fields,” European Physical Journal B, vol. 69, no. 2, pp. 237–244, 2009.
[20]
F. J. Betancur, J. Sierra-Ortega, R. A. Escorcia, J. D. González, and I. D. Mikhailov, “Density of impurity states in doped spherical quantum dots,” Physica E, vol. 23, no. 1-2, pp. 102–107, 2004.
[21]
F. J. Betancur, I. D. Mikhailov, and L. E. Oliveira, “Shallow donor states in GaAs-(Ga, Al)As quantum dots with different potential shapes,” Journal of Physics D, vol. 31, p. 3391, 1998.
[22]
S. V. Nistor, M. Stefan, L. C. Nistor, E. Goovaerts, and G. van Tendeloo, “Incorporation and localization of substitutional Mn2+ ions in cubic ZnS quantum dots,” Physical Review B, vol. 81, no. 3, Article ID 035336, 6 pages, 2010.
[23]
S. V. Nistor, L. C. Nistor, M. Stefan et al., “Synthesis and characterization of Mn2+ doped ZnS nanocrystals self-assembled in a tight mesoporous structure,” Superlattices and Microstructures, vol. 46, no. 1-2, pp. 306–311, 2009.
[24]
C. A. Duque, N. Porras-Montenegro, Z. Barticevic, M. Pacheco, and L. E. Oliveira, “Electron-hole transitions in self-assembled InAs/GaAs quantum dots: effects of applied magnetic fields and hydrostatic pressure,” Microelectronics Journal, vol. 36, no. 3–6, pp. 231–233, 2005.
[25]
E. Paspalakis and A. F. Terzis, “Controlled excitonic population transfer in a quantum dot system interacting with an electromagnetic field: local field effects,” in Proceedings of the 5th International Conference on Microelectronics, Nanoelectronics and Optoelectronics, pp. 44–49, Prague, Czech Republic, 2006.
[26]
A. Fountoulakis, A. F. Terzis, and E. Paspalakis, “Coherent single-electron transfer in coupled quantum dots,” Journal of Applied Physics, vol. 106, no. 7, Article ID 074305, 8 pages, 2009.
[27]
N. K. Datta and M. Ghosh, “Oscillatory impurity potential induced dynamics of doped quantum dots: analysis based on coupled influence of impurity coordinate and impurity influenced domain,” Chemical Physics, vol. 372, no. 1–3, pp. 82–88, 2010.
[28]
N. K. Datta and M. Ghosh, “The randomly fluctuating impurity strength initiated excitation in doped quantum dots,” Superlattices and Microstructures, vol. 51, no. 5, pp. 690–698, 2012.
[29]
N. K. Datta, S. Pal, and M. Ghosh, “Influence of relative confinement oscillation and concomitant oscillatory impurity domain on excitation profile of doped quantum dots,” Chemical Physics, vol. 400, pp. 44–50, 2012.
[30]
N. K. Datta, S. Pal, and M. Ghosh, “Influence of impurity propagation and concomitant enhancement of impurity spread on excitation profile of doped quantum dots,” Journal of Applied Physics, vol. 112, no. 1, Article ID 014324, 8 pages, 2012.
[31]
L. Jacak, P. Hawrylak, and A. Wojos, Quantum Dots, Springer, Berlin, Germany, 1998.
[32]
T. Chakraborty, Quantum Dots-A Survey of the Properties of Artificial Atoms, Elsevier, Amsterdam, The Netherlands, 1999.
[33]
W. Xie and J. Gu, “Exciton bound to a neutral donor in parabolic quantum dots,” Physics Letters A, vol. 312, no. 5-6, pp. 385–390, 2003.
[34]
S. Baskoutas, A. F. Terzis, and E. Voutsinas, “Binding energy of donor states in a quantum dot with parabolic confinement,” Journal of Computational and Theoretical Nanoscience, vol. 1, no. 3, pp. 317–321, 2004.
[35]
V. Halonen, P. Hyv？nen, P. Pietil？inen, and T. Chakraborty, “Effects of scattering centers on the energy spectrum of a quantum dot,” Physical Review B, vol. 53, no. 11, pp. 6971–6974, 1996.
[36]
V. Halonen, P. Pietil？inen, and T. Chakraborty, “Optical-absorption spectra of quantum dots and rings with a repulsive scattering centre,” Europhysics Letters, vol. 33, no. 5, pp. 377–382, 1996.
[37]
J. Adamowski, A. Kwa？niowski, and B. Szafran, “LO-phonon-induced screening of electron-electron interaction in centres and quantum dots,” Journal of Physics Condensed Matter, vol. 17, no. 28, pp. 4489–4500, 2005.
[38]
S. Bednarek, B. Szafran, K. Lis, and J. Adamowski, “Modeling of electronic properties of electrostatic quantum dots,” Physical Review B, vol. 68, no. 15, Article ID 155333, 9 pages, 2003.
[39]
B. Szafran, S. Bednarek, and J. Adamowski, “Parity symmetry and energy spectrum of excitons in coupled self-assembled quantum dots,” Physical Review B, vol. 64, no. 12, Article ID 125301, 10 pages, 2001.
[40]
A. Gharaati and R. Khordad, “A new confinement potential in spherical quantum dots: modified gaussian potential,” Superlattices and Microstructures, vol. 48, no. 3, pp. 276–287, 2010.
[41]
W. Xie, “Excited state absorptions of an exciton bound to an ionized donor impurity in quantum dots,” Optics Communications, vol. 284, no. 24, pp. 5730–5733, 2011.
