Semiconductor heterojunctions

Margaritondo G (ed) 1988 E/eofro/r/o Structure of Semiconductor Heterojunctions (MWan Kluwer)... 

Structural information on the atomic arrangements at the early stage of formation of metal-metal, metal-semiconductor interfaces and semiconductor-semiconductor heterojunctions is needed along with the determination of the structure of the electron states in order to put on a complete experimental ground the discussion of the formation of solid-solid junctions. Amongst the structural tools that have been applied to the interface formation problem Surface-EXAFS is probably the best... 

Rand BP, Burk DP, Forrest SR (2007) Offset energies at organic semiconductor heterojunctions and their infiuence on the open-circuit voltage of thin-film solar cells. Phys Rev B 75 115327... 

Morteani AC, Sreearunothai P, Herz LM, Friend RH, Silva C (2004) Exciton regeneration at polymeric semiconductor heterojunctions. Phys Rev Lett 92 247402... 

Dupuis RD (2000) III-V semiconductor heterojunction devices grown by metalorganic chemical vapor deposition. leee Journal of Selected Topics in Quantum Electronics 6(6), 1040-1050... 

Although conventional solar cells based on silicon are produced from abundant raw materials, the high-temperature fabrication routes to single-crystal and polycrystalline silicon are energy intensive and expensive. The search for alternative solar cells has therefore focused on thin films composed of amorphous silicon and on other semiconductor heterojunction cells (e.g., cadmium telluride and copper indium... 

Bach et al. have successfully introduced the concept of a solid p-type semiconductor (heterojunction), with the amorphous organic hole-transport material 2,2, 7,7 -tetrakis (, V, V-di-/ -methoxyphcnyl-aminc)9,9 -spirobifluorenc [96]. This hole-conducting material allows the regeneration of the sensitizers after electron injection due to its hole-transport properties. Nevertheless, the incident photon-to-current conversion efficiencies using complex 22 as a charge-transfer sensitizer... 

Experimental determinations of barrier heights on oxide semiconductor interfaces using photoelectron spectroscopy are rarely found in literature and no systematic data on interface chemistry and barrier formation on any oxide are available. So far, most of the semiconductor interface studies by photoelectron spectroscopy deal with interfaces with well-defined substrate surfaces and film structures. Mostly single crystal substrates and, in the case of semiconductor heterojunctions, lattice matched interfaces are investigated. Furthermore, highly controllable deposition techniques (typically molecular beam epitaxy) are applied, which lead to films and interfaces with well-known structure and composition. The results described in the following therefore, for the first time, provide information about interfaces with oxide semiconductors and about interfaces with sputter-deposited materials. Despite the rather complex situation, photoelectron spectroscopy studies of sputter-deposited... 

Dingle, R. Stormer, H.L. Gossard, A.C. Wiegmann, W. Electron mobilities in modulation-doped semiconductor heterojunction superlattices. Appl. Phys. Lett. 1978, 33, 665. 

Photoelectric Properties of Microrelief Organic/Inorganic Semiconductor Heterojunctions... 

Layered nanostructures can be deposited from the electrochemical environment by applying a time dependent voltage program to the working electrode (5) or by using a sequential deposition scheme such as electrochemical atomic layer epitaxy (EC-ALE) (6-10). In EC-ALE, a surface-limited electrochemical reaction, such as underpotential deposition (upd), is used to synthesize a binary compound by successive deposition of each element from its respective solution precursor. EC-ALE is an attractive electrosynthetic alternative to conventional deposition methods that is inexpensive, operates at ambient temperature and pressure and provides precise film thickness control. This technique promises to overcome many problems associated with other electrosynthetic approaches, such as the formation of highly polycrystalline deposits and interfacial interdiffusion. For example, we have recently used EC-ALE to fabricate stable semiconductor heterojunctions with extremely abrupt interfaces (11). 

Recently, Foreman demonstrated that fe-linear terms in semiconductor heterojunctions [47] are enhanced near the interface, and that the associated mixing of Fg hh and Ih states is increased so that it influences the quantum-well Pockels effect. [48] The reduced symmetry in quantum well structures (from Td in the bulk to C2v) increases the optical anisotropy. The work in Ref. [47] shows that the A -linear splitting contributes significantly to this anisotropy because the C coefficients are often an order of magnitude larger in the heterojunctions than in the bulk materials. 

Thus, although the examples are rather limited, it appears that the large amount of interdiffusion which characterizes many metal—semiconductor systems does not occur with semiconductor heterojunctions. This would imply that the mechanism proposed by Spicer et al. [298, 326, 327] in terms of the heat of condensation of the overlayer is not universally applicable. The fundamental difference between semiconductor and metal deposits is that the latter induce instability in the covalent bonding of the semiconductor substrate, perhaps by their ability to screen Coulomb interactions due to their mobile free electrons. 

Tersoff, Theory of semiconductor heterojunctions the role of quantum dipoles, Phys. Rev. B30, 4874 (1984). 

Jishiashvili, Proceedings of the International Conference on the Chemistry of Semiconductors Heterojunction Layer... 

Sharma, B. L. and Purohit, R. K. 1974. Semiconductor Heterojunctions, B. R. Pamplin (ed.). International Series of Monographs in the Science of the Solid State. New York Pergamon Press. 

Hsu, L. and Wang, E.Y. (1972) Photovoltaic properties of In203/ semiconductor heterojunction solar cells, in Proc. 13th Photovoltaic Specialists Conference, IEEE, New York, pp. 536-540. 

Figure 13.2 Schematic energy-level diagram for type I and type II organic semiconductor heterojunctions where and electrodes work function are also indicated. For type II,...

Figure 13.8 Interfacial excitations. Schematic of the lowest excitonic excitations at the heterojunction of the PFB F8BT and the TFB F8BT systems. TFB abbreviates poly(9,9-dioctyl-fluorene-co-U-(4-butylphenyl)diphenylamine) and can be used to fabricate highly efficient OLEDs when blended with F8BT. (Reprinted with permission from Nature Materials, Electronic structures of interfacial states formed at polymeric semiconductor heterojunctions. Nature Materials by Y.-s. Huang, S. Westenhoff, I. Avilov et al., 7, 483-489. Copyright (2008) Macmillan Publishers Ltd)...

R. H. Friend, and D. Beljonne, Electronic structures of interfacial states formed at polymeric semiconductor heterojunctions. Nature Mater., 7,483-489 (2008). 

P. Sreearunothai, A.C. Morteani, I. Avilov, J. Comil, D. Beljonne, R.H. Friend, R.T. Phillips, C. Silva, and L.M. Herz, Influence of copolymer interface orientation on the optical emission of polymeric semiconductor heterojunctions, Phys. Rev. Lett., 96, 117403 (2006). 

Phase boundaries can be like GBs where the adjoining two grains may not only be rotated relative to one another but will also (or instead) be structurally and/or chemically different of course, one or both phases may be a glass, which means the interface is not structured. As with heterojunctions, the word hetero is implied when we say phase boundaries. Semiconductor heterojunctions are examples of PBs heterojunction usually indicates that we are talking about flat interfaces and a thin-film geometry. As is the case with GBs, almost all the detailed studies have been concerned with special PBs. We can summarize this idea and compare some PBs to GBs. 

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