Quantum dot array

A QD array structure enables electronic and optical interaction between neighboring QDs. Recently, exciton interactions between QDs have become desirable for certain novel devices [42]. In normal SK growth, the 3D islands are randomly deposited on a surface. However, the self-formation of arranged QDs can be achieved by modification of the underlying layers. In this section, the self-arrangement of vertical and in-plane InAs/GaAs QDs is described. 

1 Vertical Array of InAs/GaAs Quantum Dots 

2 In-Plane Arrays ofInAs/GaAs Quantum Dots 

3 InAs QDs on GaAs b InAs QDs on GaAs/InGaAs/GaAs 

Bimbetg, M. Grundmann, N.N. Ledentsov, in chapter 4, Growth and Structural Characterization cif Self-Organized quantum dots. Quantum Dot Heterostiuctuies (Wiley, New York, 1999) 

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A key issue is the improvement of solar light harvesting. New active materials with high optical absorption in the visible and good photostability are needed. Implementation of carrier multiplication through impact ionization in quantum dots arrays could mitigate the losses related to carrier thermalization. The alternative approach is the development of vertically stacked tandem systems of increasing band gap active materials, which effect H+ reduction and water oxidation on opposite sides. 

D. Novikov, M. Drndic, L. Levitov, M. Kastner, M. Jarosz, and M. Bawendi, Anomalous transport in quantum dot arrays, cond-mat/0307031 (2003). 

The method of templated self assembly has been recently successfully implemented for the growth of ordered arrays of InAs as well as Ge islands in 2-and 3-dimensional arrays and quantum dot crystals [1] by molecular beam epitaxy (MBE). The quantum dot arrays fabricated by templated self-assembly exhibit narrow size distributions and perfect ordering [2]. Thus, this technology enables fabrication of nanodevices requiring exact positioning of quantum dots [3] and offers a suitable path for the demonstration of spintronics and manipulation of qubits [4]. 

Kim YT, Han JH, Hong BH, Kwon YU (2010) Electroehemieal synthesis of CdSe quantum-dot arrays on a graphene basal plane using mesoporous silica thin-film templates. Adv Mater 22 515... 

Nozik AJ, Beard MC, Luther JM, Law M, Ellingson RJ, Johnson JC (2010) Scaniconductra quantum dots and quantum dot arrays and applications of multiple exciton goieration to third generation photovoltaic solar cells. Chem Rev 110 6873-6890... 

Fu, Y., Willander, M., Ivchenko, E. L. (2000). Photonic dispersions of semiconductor-quantum-dot-array-based photonic crystals in primitive and face-centered cubic lattices. Superlattices and Microstructures, 27, 255-264. 

Semiconductor NCs have been incorporated into solar cells in different configurations, for example (a) photoelectrodes composed of quantum dot arrays, (b) metal-semiconductor photovoltaic cells,(c) NC-polymer solar cells and (d) quantum dot sensitized solar cells. This field has been the focus of intense research in recent years because of the possibility that quantum dot-based solar cells can overcome the Shockley-Queisser photoconversion limit. This possibility relies on two feasible processes hot carrier extraction and multiple exciton generation (MEG). 

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