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Top 20 Most Read Articles
April 2007
The 20 articles with the most full-text downloads during the month, in descending order.
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A comprehensive review of ZnO materials and devices J. Appl. Phys. 98, 041301 (2005); http://dx.doi.org/10.1063/1.1992666 (103 pages) Online Publication Date: 30 August 2005
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The semiconductor ZnO has gained substantial interest in the research community in part because of its large exciton binding energy (60 meV) which could lead to lasing action based on exciton recombination even above room temperature. Even though research focusing on ZnO goes back many decades, the renewed interest is fueled by availability of high-quality substrates and reports of p-type conduction and ferromagnetic behavior when doped with transitions metals, both of which remain controversial. It is this renewed interest in ZnO which forms the basis of this review. As mentioned already, ZnO is not new to the semiconductor field, with studies of its lattice parameter dating back to 1935 by
Bunn [Proc. Phys. Soc. London 47, 836 (1935)
], studies of its vibrational properties with Raman scattering in 1966 by
Damen et al. [Phys. Rev. 142, 570 (1966)
], detailed optical studies in 1954 by
Mollwo [Z. Angew. Phys. 6, 257 (1954)
], and its growth by chemical-vapor transport in 1970 by
Galli and Coker [Appl. Phys. Lett. 16, 439 (1970)
]. In terms of devices, Au Schottky barriers in 1965 by
Mead [Phys. Lett. 18, 218 (1965)
], demonstration of light-emitting diodes (1967) by
Drapak [Semiconductors 2, 624 (1968)
], in which Cu2O was used as the p-type material, metal-insulator-semiconductor structures (1974) by
Minami et al. [Jpn. J. Appl. Phys. 13, 1475 (1974)
], ZnO/ZnSe n-p junctions (1975) by
Tsurkan et al. [Semiconductors 6, 1183 (1975)
], and Al/Au Ohmic contacts by
Brillson [J. Vac. Sci. Technol. 15, 1378 (1978)
] were attained. The main obstacle to the development of ZnO has been the lack of reproducible and low-resistivity p-type ZnO, as recently discussed by
Look and Claflin [Phys. Status Solidi B 241, 624 (2004)
]. While ZnO already has many industrial applications owing to its piezoelectric properties and band gap in the near ultraviolet, its applications to optoelectronic devices has not yet materialized due chiefly to the lack of p-type epitaxial layers. Very high quality what used to be called whiskers and platelets, the nomenclature for which gave way to nanostructures of late, have been prepared early on and used to deduce much of the principal properties of this material, particularly in terms of optical processes. The suggestion of attainment of p-type conductivity in the last few years has rekindled the long-time, albeit dormant, fervor of exploiting this material for optoelectronic applications. The attraction can simply be attributed to the large exciton binding energy of 60 meV of ZnO potentially paving the way for efficient room-temperature exciton-based emitters, and sharp transitions facilitating very low threshold semiconductor lasers. The field is also fueled by theoretical predictions and perhaps experimental confirmation of ferromagnetism at room temperature for potential spintronics applications. This review gives an in-depth discussion of the mechanical, chemical, electrical, and optical properties of ZnO in addition to the technological issues such as growth, defects, p-type doping, band-gap engineering, devices, and nanostructures.
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High-κ gate dielectrics: Current status and materials properties considerations J. Appl. Phys. 89, 5243 (2001); http://dx.doi.org/10.1063/1.1361065 (33 pages)
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Many materials systems are currently under consideration as potential replacements for SiO2 as the gate dielectric material for sub-0.1 μm complementary metal–oxide–semiconductor (CMOS) technology. A systematic consideration of the required properties of gate dielectrics indicates that the key guidelines for selecting an alternative gate dielectric are (a) permittivity, band gap, and band alignment to silicon, (b) thermodynamic stability, (c) film morphology, (d) interface quality, (e) compatibility with the current or expected materials to be used in processing for CMOS devices, (f) process compatibility, and (g) reliability. Many dielectrics appear favorable in some of these areas, but very few materials are promising with respect to all of these guidelines. A review of current work and literature in the area of alternate gate dielectrics is given. Based on reported results and fundamental considerations, the pseudobinary materials systems offer large flexibility and show the most promise toward successful integration into the expected processing conditions for future CMOS technologies, especially due to their tendency to form at interfaces with Si (e.g. silicates). These pseudobinary systems also thereby enable the use of other high-κ materials by serving as an interfacial high-κ layer. While work is ongoing, much research is still required, as it is clear that any material which is to replace SiO2 as the gate dielectric faces a formidable challenge. The requirements for process integration compatibility are remarkably demanding, and any serious candidates will emerge only through continued, intensive investigation. © 2001 American Institute of Physics. |
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Surface-state related luminescence in ZnO nanocrystals J. Appl. Phys. 101, 073506 (2007); http://dx.doi.org/10.1063/1.2718290 (4 pages) Online Publication Date: 4 April 2007
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We investigate the optical properties of four different samples of ZnO nanocrystals, with a particle size average varying from 70 up to 380 nm. The photoluminescence (PL) of all samples shows at low temperature an emission band around 3.31 eV, which is several orders of magnitude stronger compared to the PL of bulk ZnO at this energy. This band shows a clear dependence on the surface to volume ratio of the nanocrystals and is therefore assigned to surface states. Temperature dependent measurements reveal that this band plays a major role up to room temperature for all examined ZnO powders. Additionally, intensity dependent measurements display that the origin of this emission band can be assigned to bound exciton complexes (BECs). Compared to the well known shallow BECs the measured lifetimes of these relatively strong bound excitons states are much longer.
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Band parameters for III–V compound semiconductors and their alloys J. Appl. Phys. 89, 5815 (2001); http://dx.doi.org/10.1063/1.1368156 (61 pages)
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We present a comprehensive, up-to-date compilation of band parameters for the technologically important III–V zinc blende and wurtzite compound semiconductors: GaAs, GaSb, GaP, GaN, AlAs, AlSb, AlP, AlN, InAs, InSb, InP, and InN, along with their ternary and quaternary alloys. Based on a review of the existing literature, complete and consistent parameter sets are given for all materials. Emphasizing the quantities required for band structure calculations, we tabulate the direct and indirect energy gaps, spin-orbit, and crystal-field splittings, alloy bowing parameters, effective masses for electrons, heavy, light, and split-off holes, Luttinger parameters, interband momentum matrix elements, and deformation potentials, including temperature and alloy-composition dependences where available. Heterostructure band offsets are also given, on an absolute scale that allows any material to be aligned relative to any other. © 2001 American Institute of Physics. |
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J. Appl. Phys. 97, 011101 (2005); http://dx.doi.org/10.1063/1.1819976 (28 pages) Online Publication Date: 9 December 2004
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This article reviews the history and current progress in high-mobility strained Si, SiGe, and Ge channel metal-oxide-semiconductor field-effect transistors (MOSFETs). We start by providing a chronological overview of important milestones and discoveries that have allowed heterostructures grown on Si substrates to transition from purely academic research in the 1980’s and 1990’s to the commercial development that is taking place today. We next provide a topical review of the various types of strain-engineered MOSFETs that can be integrated onto relaxed Si1−xGex, including surface-channel strained Si n- and p-MOSFETs, as well as double-heterostructure MOSFETs which combine a strained Si surface channel with a Ge-rich buried channel. In all cases, we will focus on the connections between layer structure, band structure, and MOS mobility characteristics. Although the surface and starting substrate are composed of pure Si, the use of strained Si still creates new challenges, and we shall also review the literature on short-channel device performance and process integration of strained Si. The review concludes with a global summary of the mobility enhancements available in the SiGe materials system and a discussion of implications for future technology generations.
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Plasmonics: Localization and guiding of electromagnetic energy in metal/dielectric structures J. Appl. Phys. 98, 011101 (2005); http://dx.doi.org/10.1063/1.1951057 (10 pages) Online Publication Date: 11 July 2005
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We review the basic physics of surface-plasmon excitations occurring at metal/dielectric interfaces with special emphasis on the possibility of using such excitations for the localization of electromagnetic energy in one, two, and three dimensions, in a context of applications in sensing and waveguiding for functional photonic devices. Localized plasmon resonances occurring in metallic nanoparticles are discussed both for single particles and particle ensembles, focusing on the generation of confined light fields enabling enhancement of Raman-scattering and nonlinear processes. We then survey the basic properties of interface plasmons propagating along flat boundaries of thin metallic films, with applications for waveguiding along patterned films, stripes, and nanowires. Interactions between plasmonic structures and optically active media are also discussed.
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Ferroelectric thin films: Review of materials, properties, and applications J. Appl. Phys. 100, 051606 (2006); http://dx.doi.org/10.1063/1.2336999 (46 pages) Online Publication Date: 12 September 2006
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An overview of the state of art in ferroelectric thin films is presented. First, we review applications: microsystems’ applications, applications in high frequency electronics, and memories based on ferroelectric materials. The second section deals with materials, structure (domains, in particular), and size effects. Properties of thin films that are important for applications are then addressed: polarization reversal and properties related to the reliability of ferroelectric memories, piezoelectric nonlinearity of ferroelectric films which is relevant to microsystems’ applications, and permittivity and loss in ferroelectric films—important in all applications and essential in high frequency devices. In the context of properties we also discuss nanoscale probing of ferroelectrics. Finally, we comment on two important emerging topics: multiferroic materials and ferroelectric one-dimensional nanostructures.
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Magnetoresistance and anomalous Hall effect in magnetic ZnO films J. Appl. Phys. 101, 063918 (2007); http://dx.doi.org/10.1063/1.2715846 (5 pages) Online Publication Date: 29 March 2007
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Magnetotransport measurements were performed on n-type conducting Co-doped ZnO and Mn-doped ZnO films prepared by pulsed laser deposition on a-plane sapphire substrates, and positive magnetoresistance (MR) was observed at low temperature. The positive MR decreases drastically with the free electron concentration n exceeding 1019 cm−3 and reveals almost the same dependency on n for Co-doped ZnO and Mn-doped ZnO. This hints towards a similar s-d exchange constant in both types of magnetic ZnO films. For Co-doped ZnO, the saturated anomalous Hall resistivity increases with decreasing electron concentration. No anomalous Hall effect was observed in Mn-doped ZnO. Within a free electron approximation the positive MR may be related with the spin polarization of conducting electrons due to s-d exchange interactions. The modeled spin splitting of the conduction band is smaller than 10 meV.
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J. Appl. Phys. 101, 044505 (2007); http://dx.doi.org/10.1063/1.2495754 (7 pages) Online Publication Date: 21 February 2007
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The role of order and disorder on the electronic performances of n-type ionic oxides such as zinc oxide, gallium zinc oxide, and indium zinc oxide used as active (channel) or passive (drain/source) layers in thin film transistors (TFTs) processed at room temperature are discussed, taking as reference the known behavior observed in conventional covalent semiconductors such as silicon. The work performed shows that while in the oxide semiconductors the Fermi level can be pinned up within the conduction band, independent of the state of order, the same does not happen with silicon. Besides, in the oxide semiconductors the carrier mobility is not bandtail limited and so disorder does not affect so strongly the mobility as it happens in covalent semiconductors. The electrical properties of the oxide films (resistivity, carrier concentration, and mobility) are highly dependent on the oxygen vacancies (source of free carriers), which can be controlled by changing the oxygen partial pressure during the deposition process and/or by adding other metal ions to the matrix. In this case, we make the oxide matrix less sensitive to the presence of oxygen, widening the range of oxygen partial pressures that can be used and thus improving the process control of the film resistivity. The results obtained in fully transparent TFT using polycrystalline ZnO or amorphous indium zinc oxide (IZO) as channel layers and highly conductive poly/nanocrystalline ZGO films or amorphous IZO as drain/source layers show that both devices work in the enhancement mode, but the TFT with the highest electronic saturation mobility and on/off ratio 49.9 cm2/V s and 4.3×108, respectively, are the ones in which the active and passive layers are amorphous. The ZnO TFT whose channel is based on polycrystalline ZnO, the mobility and on/off ratio are, respectively, 26 cm2/V s and 3×106. This behavior is attributed to the fact that the electronic transport is governed by the s-like metal cation conduction bands, not significantly affected by any type of angular disorder promoted by the 2p O states related to the valence band, or small amounts of incorporated metal impurities that lead to a better control of vacancies and of the TFT off current.
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J. Appl. Phys. 101, 073101 (2007); http://dx.doi.org/10.1063/1.2714003 (4 pages) Online Publication Date: 4 April 2007
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We investigate the effect of the properties of an intracavity diamond heat spreader on the lasing performance of vertical-external-cavity surface-emitting lasers. We compared two intracavity diamonds with different average birefringences. When a polarization selective element is inserted into the cavity, the infrared output powers are reduced by 13% and 7%, respectively, for the samples with higher and lower average birefringences. The pump-power limited maximum green output powers were changed from 3 to 5.2 W by rotating the samples with lower average birefringence. In order to explain the variation in green output power, the additional round-trip loss caused by diamond birefringence was analyzed theoretically and experimentally. We found that the loss can be reduced when axes of the birefringence are aligned to the axes of the polarization selective element.
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J. Appl. Phys. 101, 064504 (2007); http://dx.doi.org/10.1063/1.2710297 (4 pages) Online Publication Date: 19 March 2007
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Electronic structures of organic/organic (O/O) heterojunctions have been studied by photoemission spectroscopy. We showed that vacuum level alignment is only valid for certain O/O heterojunctions rather than a general rule for organic junctions. The mode of energy level alignment is found to depend on the Fermi level position in the organic energy gap. In general, when the Fermi level is near the midgap position, vacuum level alignment at the O/O heterojunction is observed, whereas when the Fermi level is close to the edge of the lowest unoccupied or highest occupied molecular orbital level, Fermi level pinning accompanied by molecular orbital level bending is observed at the O/O heterojunction.
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Microcavity enhanced spontaneous emission from silicon nanocrystals J. Appl. Phys. 101, 073108 (2007); http://dx.doi.org/10.1063/1.2715839 (4 pages) Online Publication Date: 11 April 2007
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An approach fully based on the rf magnetron sputtering of a pure silica target has been developed to deposit a silicon nanocrystal based optical planar microcavity. Tunable narrow emission bands, directionality of the radiation pattern along the normal of the cavity surface, and resonant enhancement of the luminescence intensity have been demonstrated. Time resolved photoluminescence measurements also confirmed an increase of the spontaneous emission rate of silicon nanocrystals when they are embedded inside the optical resonator. These results are attributed to the anisotropic redistribution of the optical density of states induced by the resonator.
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The structural and luminescence properties of porous silicon J. Appl. Phys. 82, 909 (1997); http://dx.doi.org/10.1063/1.366536 (57 pages)
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A large amount of work world-wide has been directed towards obtaining an understanding of the fundamental characteristics of porous Si. Much progress has been made following the demonstration in 1990 that highly porous material could emit very efficient visible photoluminescence at room temperature. Since that time, all features of the structural, optical and electronic properties of the material have been subjected to in-depth scrutiny. It is the purpose of the present review to survey the work which has been carried out and to detail the level of understanding which has been attained. The key importance of crystalline Si nanostructures in determining the behaviour of porous Si is highlighted. The fabrication of solid-state electroluminescent devices is a prominent goal of many studies and the impressive progress in this area is described. © 1997 American Institute of Physics. |
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J. Appl. Phys. 101, 074102 (2007); http://dx.doi.org/10.1063/1.2713934 (9 pages) Online Publication Date: 3 April 2007
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We studied theoretically the influence of the progressive strain relaxation and the depolarizing-field effect on the thickness dependence of the out-of-plane dielectric response of epitaxial ferroelectric thin films sandwiched between extended metal electrodes. The calculations show that the inverse of the measured capacitance varies with the film thickness almost linearly in the most part of the thickness range at the majority of temperatures. Extrapolation of this linear dependence to zero thickness usually gives considerable nonzero intercept even in the absence of nonferroelectric interfacial layers. Remarkably, such apparent “interfacial capacitance” in a certain temperature range becomes negative. The physical meaning of the effective dielectric constant, which can be extracted from the slope of the reciprocal capacitance thickness dependence, is also analyzed. The theoretical predictions are compared with the experimental data obtained for single-crystalline SrRuO3/Ba0.7Sr0.3TiO3/SrRuO3 and Pt/Ba0.7Sr0.3TiO3/SrRuO3 thin-film capacitors.
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J. Appl. Phys. 101, 073902 (2007); http://dx.doi.org/10.1063/1.2715841 (4 pages) Online Publication Date: 2 April 2007
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Room temperature ferromagnetic Zn0.95Co0.05O thin film with (002) preferential orientation has been deposited by pulsed laser deposition at different substrate temperatures on n-type (100) silicon substrate. A maximum saturation magnetization of 0.86μB/Co was achieved at room temperature. High-resolution transmission electron microscope and x-ray photoelectron spectroscopy results indicate that this ferromagnetism behavior is not due to Co microclusters in the thin film. Zinc interstitials, oxygen vacancies, and lattice defects induced by low substrate deposition temperature show a significant effect on ferromagnetic behavior. By changing the substrate deposition temperature to control the amount of zinc interstitials, oxygen vacancies, and lattice defects, ferromagnetism can be tuned significantly as well, which is a direct evidence that these defects contributed to the ferromagnetism in ZnO:Co thin films.
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J. Appl. Phys. 101, 074108 (2007); http://dx.doi.org/10.1063/1.2715513 (6 pages) Online Publication Date: 6 April 2007
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BiFeO3 (BFO) thin films were fabricated on Pt(111)/Ti/SiO2/Si substrates by using a polymeric precursor solution under appropriate crystallization conditions. The capacitance dependence on voltage is strongly nonlinear, confirming the ferroelectric properties of the films resulting from the domain switching. The leakage current density increases with annealing temperature. The polarization electric field curves could be obtained in BFO films annealed at 500 °C, free of secondary phases. X-ray photoelectron spectroscopy spectra of films annealed at 500 °C indicated that the oxidation state of Fe was purely 3+, demonstrating that our films possess stable chemical configurations.
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The role of oxygen vacancies in epitaxial-deposited ZnO thin films J. Appl. Phys. 101, 053106 (2007); http://dx.doi.org/10.1063/1.2437122 (8 pages) Online Publication Date: 7 March 2007
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ZnO thin films were epitaxial deposited on sapphire (0001) substrates at various temperatures by using the pulsed laser deposition (PLD) technique. An x-ray diffractometer (XRD) was used to investigate the structural properties of the thin film. It was found that all of the thin films were (0002) oriented and the intensity of (0002) peak increased with the increasing growth temperature. The ϕ-scans for the thin films indicated that the thin film grown at a temperature higher than 400 °C had an epitaxial relation with the substrate. An atomic force microscope (AFM) was used to investigate the surface morphologies of the thin films. The surface roughness and grain size of the thin films increased with increasing growth temperature. A double-beam spectrophotometer was used to measure the transmittances of the thin films. The band gap energies of the thin films were calculated by linear fitting the absorption edges for high-quality thin films. A spectrometer was used to investigate the photoluminescent (PL) properties of the thin films. It was discovered that all of the thin films showed two emissions. One was the near band edge (NBE) emission; the other was the broad deep-level (DL) emission. After checking the PL of the thin films on a different date, the aging effect of the ZnO thin film on the sapphire substrate deposited by PLD was observed. It was revealed that, the NBE emissions were enhanced and the DL emissions were decreased with time. To find the reason why the DL emission decreased with time, the as-deposited thin films were annealed at 800 °C in a N2 and O2 atmosphere for 30 min, respectively. The surface morphologies and the transmittances of the annealed thin films were investigated by the AFM and spectrophotometer. The surface roughness and the transmittance decreased much after annealing. The PL measurements for the annealed thin films indicated that, the DL emission of the thin film annealed in N2 was enhanced and that annealed in O2 was quenched. It was suggested that the oxygen vacancies, instead of zinc interstitials, played the most important role for DL emissions in ZnO thin films deposited by PLD.
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Small molecular weight organic thin-film photodetectors and solar cells J. Appl. Phys. 93, 3693 (2003); http://dx.doi.org/10.1063/1.1534621 (31 pages) Online Publication Date: 21 March 2003
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In this review, we discuss the physics underlying the operation of single and multiple heterojunction, vacuum-deposited organic solar cells based on small molecular weight thin films. For single heterojunction cells, we find that the need for direct contact between the deposited electrode and the active organics leads to quenching of excitons. An improved device architecture, the double heterojunction, is shown to confine excitons within the active layers, allowing substantially higher internal efficiencies to be achieved. A full optical and electrical analysis of the double heterostructure architecture leads to optimal cell design as a function of the optical properties and exciton diffusion lengths of the photoactive materials. Combining the double heterostructure with novel light trapping schemes, devices with external efficiencies approaching their internal efficiency are obtained. When applied to an organic photovoltaic cell with a power conversion efficiency of 1.0%±0.1% under 1 sun AM1.5 illumination, devices with external power conversion efficiencies of 2.4%±0.3% are reported. In addition, we show that by using materials with extended exciton diffusion lengths LD, highly efficient double heterojunction photovoltaic cells are obtained, even in the absence of a light trapping geometry. Using C60 as an acceptor material, double heterostructure external power conversion efficiencies of 3.6%±0.4% under 1 sun AM1.5 illumination are obtained. Stacking of single heterojunction devices leads to thin film multiple heterojunction photovoltaic and photodetector structures. Thin bilayer photovoltaic cells can be stacked with ultrathin (∼5 Å), discontinuous Ag layers between adjacent cells serving as efficient recombination sites for electrons and holes generated in the neighboring cells. Such stacked cells have open circuit voltages that are n times the open circuit voltage of a single cell, where n is the number of cells in the stack. In optimized structures, the short circuit photocurrent remains approximately constant upon stacking thin cells, leading to higher achievable power conversion efficiencies, as confirmed by modelling optical interference effects and exciton migration. A 2.5%±0.3% power efficiency under 100 mW/cm2 AM1.5 illumination conditions is obtained by stacking two ∼1% efficient devices. Alternatively, when the contact layers between the stacked cells are eliminated, a multilayer structure consisting of alternating films of donor and acceptor-type materials is obtained. Since the thicknesses of the individual layers (∼5 Å) can be substantially smaller than the exciton diffusion length, nearly 100% of the photogenerated excitons are dissociated, and the resulting free charges are detected. In addition, the ultrathin organic layers facilitate electron and hole transport through the multilayer stack by tunneling. When these devices are operated as photodetectors under applied fields >106 V/cm, the carrier collection efficiency reaches 80%, leading to external quantum efficiencies of 75%±1% across the visible spectrum in cells containing the thinnest layers. We find that due to the fast carrier tunneling process, the temporal response of these multilayer detectors is a direct measure of exciton dynamics. Response times of 720±50 ps are achieved, leading to a 3 dB bandwidth of 430±30 MHz. A summary of representative results obtained for both polymer and small molecule photovoltaic cells and photodetectors is included in this review. Prospects for further improvements in organic solar cells and photodetectors are considered. © 2003 American Institute of Physics. |
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Influence of defects on the magnetism of Mn-doped ZnO J. Appl. Phys. 101, 09H101 (2007); http://dx.doi.org/10.1063/1.2709411 (3 pages) Online Publication Date: 23 March 2007
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The properties of dilute magnetic semiconductors are usually strongly influenced by the defects present in the system. Ab initio calculations may provide valuable insight for the microscopic understanding of the interactions with defects. Here, we present studies of Mn-doped ZnO in the presence of several defects by a combined approach of ab initio electronic structure calculations using Korringa-Kohn-Rostoker-coherent potential approximation and Monte Carlo simulations (MCSs). Electronic structure and magnetic interactions have similar trends for wurtzite and zinc-blende crystal structures. A weak antiferromagnetic interaction has been found for 5% Mn doping in defect-free ZnO. Defects such as O vacancies and Zn interstitials lead to antiferromagnetic interactions between the Mn atoms, while Zn vacancies and oxygen substitution by nitrogen yield ferromagnetic interactions. As the concentration of Mn is low and the exchange interactions are short ranged, MCSs show small values of Curie temperatures (not more than 50 K). However, for a few cases with codoping of Mn and defects, we obtained higher Curie temperatures (around 130 K). Estimates of the Curie temperatures, assuming an average separation of the Mn atoms in the mean-field solution of Heisenberg model, are in very good agreement with the results obtained from MCS.
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Biocatalytic growth of semiconductor nanowires J. Appl. Phys. 101, 074306 (2007); http://dx.doi.org/10.1063/1.2720102 (5 pages) Online Publication Date: 11 April 2007
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A synthetic protocol using DNA as a biocatalyst has been described to electrodeposit HgTe-DNA nanowires (NWs). As evidenced from transmission electron microscopy, Fourier-transform infrared and optical absorption studies, the growth of HgTe NWs is ascribed to the electroactive aggregation of respective cations with DNA followed by cathodic deposition and surface diffusion. The choice of biocatalyst is shown to play an important role for NW growth, which is confirmed with the choice of two different DNA sequences. Additional confirmation of NW growth has been established for a different system, CdSe NW synthesized using the similar principle.
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