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4 Sep 2006

Volume 89, Issue 10, Articles (10xxxx)

Issue Cover Spotlight Figure

Appl. Phys. Lett. 89, 103101 (2006); http://dx.doi.org/10.1063/1.2345352 (3 pages)

F. Hao and P. Nordlander
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Tunable electromagnetic noise suppressor integrated with a magnetic thin film

Jaecheon Sohn, S. H. Han, M. Yamaguchi, and S. H. Lim

Appl. Phys. Lett. 89, 103501 (2006); http://dx.doi.org/10.1063/1.2335389 (3 pages) | Cited 9 times

Online Publication Date: 5 September 2006

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A tunable electromagnetic noise suppressor based on a coplanar waveguide transmission line integrated with a magnetic thin film is presented. High resonance frequencies (above 10 GHz) and good signal attenuation characteristics are observed in the device, making it suitable for high frequency noise suppressors. The main mechanism of the loss generation is found to be the L-C resonance, not ferromagnetic resonance observed in previous similar devices. With the inclusion of a magnetic material, the resonance frequency can be tuned during the operation with an applied magnetic field.
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84.40.Ua Telecommunications: signal transmission and processing; communication satellites
75.70.-i Magnetic properties of thin films, surfaces, and interfaces
84.40.Az Waveguides, transmission lines, striplines

Mechanical strain effect of n-channel polycrystalline silicon thin-film transistors

C.-F. Huang, Y.-J. Yang, C.-Y. Peng, F. Yuan, and C. W. Liu

Appl. Phys. Lett. 89, 103502 (2006); http://dx.doi.org/10.1063/1.2344855 (3 pages) | Cited 3 times

Online Publication Date: 5 September 2006

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The current change of n-channel polycrystalline silicon thin-film transistors is analyzed experimentally and theoretically under different strain conditions. Under the uniaxial strain parallel to the channel, the +6.7% and +5.3% drain current enhancements are achieved in linear and saturation regions, respectively. There are −4.4% (linear) and −4.6% (saturation) drain current degradations when the uniaxial strain is applied perpendicular to the channel. The polycrystalline silicon is mainly composed of (111)-oriented grains, measured by electron diffraction pattern. Phonon-limited mobility is theoretically calculated. There is a qualitative agreement between experiments and theoretical analysis.
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85.30.Tv Field effect devices
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Long-pulse operation of a megawatt-class plasma-assisted slow-wave oscillator

A. G. Shkvarunets, J. Rodgers, Y. Carmel, and G. S. Nusinovich

Appl. Phys. Lett. 89, 103503 (2006); http://dx.doi.org/10.1063/1.2344856 (3 pages) | Cited 9 times

Online Publication Date: 5 September 2006

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Demonstration of a plasma-assisted, helix-based slow-wave 1.2 GHz oscillator (pasotron) operating at megawatt power levels with pulse durations of approximately 0.6 ms and generating about 0.6 kJ of microwave energy per pulse without pulse shortening is presented. This result was achieved in spite of significant voltage and current drop as well as the temporal evolution of the gas pressure in the interaction space during the rf pulse. The conditions for stable operation or mode hopping were studied and experimentally observed. The physical interpretation for this effect, which was caused by drop in the accelerating voltage due to limited energy storage in the power supply, is given. The results indicate that stable, high-efficiency, single mode operation of the pasotron with output energy of 1 kJ/pulse and beyond can be realized.
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52.75.-d Plasma devices
07.57.Hm Infrared, submillimeter wave, microwave, and radiowave sources
84.30.Ng Oscillators, pulse generators, and function generators

Temperature dependence of transient and steady-state gate currents in HfO2 capacitors

Christian Monzio Compagnoni, Alessandro S. Spinelli, Andrea Bianchini, Andrea L. Lacaita, Sabina Spiga, Giovanna Scarel, Claudia Wiemer, and Marco Fanciulli

Appl. Phys. Lett. 89, 103504 (2006); http://dx.doi.org/10.1063/1.2345237 (3 pages) | Cited 1 time

Online Publication Date: 6 September 2006

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The authors investigated the temperature dependence of transient and steady-state gate currents in HfO2 capacitors from 300 to 75 K. They show that transient currents measured on very thin (5 nm) HfO2 layers keep a power-law time dependence when temperature decreases to 75 K, with only a small reduction in the current amplitude. Instead, the static gate leakage strongly decreases when temperature is reduced, also showing a change in the conduction mechanism. These results clearly demonstrate that transient currents in HfO2 dielectrics do not depend on the steady-state conduction mechanisms and are an issue that must be considered even at low temperatures.
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84.32.Tt Capacitors

Electric-field-induced fluorescence quenching in dye-doped tris(8-hydroxyquinoline) aluminum layers

Yichun Luo, Hany Aziz, Zoran D. Popovic, and Gu Xu

Appl. Phys. Lett. 89, 103505 (2006); http://dx.doi.org/10.1063/1.2337269 (3 pages) | Cited 11 times

Online Publication Date: 6 September 2006

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The authors measured electric-field-induced fluorescence quenching (EFIFQ) in both undoped and fluorescent dye-doped tris(8-hydroxyquinoline)aluminum (AlQ3) layers of organic light-emitting devices. Results show that doped AlQ3 layers demonstrate smaller EFIFQ than undoped ones. The phenomenon is attributed to the narrower energy band gap of the guest molecule relative to that of the host material, which makes it less prone to electric-field-induced dissociation of the excited state. Results also show that increasing the concentration of the guest material or decreasing its band gap leads to a decrease in EFIFQ.
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85.60.Jb Light-emitting devices
73.61.Ph Polymers; organic compounds
61.72.up Other materials
78.66.Qn Polymers; organic compounds
78.60.Fi Electroluminescence

Dielectric charge measurements in capacitive microelectromechanical switches

D. Molinero, R. Comulada, and L. Castañer

Appl. Phys. Lett. 89, 103506 (2006); http://dx.doi.org/10.1063/1.2335799 (3 pages) | Cited 6 times

Online Publication Date: 6 September 2006

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Measurements of transient currents from the discharge of microelectromechanical capacitive switches after charging the dielectric with an ion gun are reported. It is shown that both the charge sign and the charge amount can be independently measured and that the values can be related to the pull-in shift as measured from C-V characteristics. Several capacitive switches of different sizes were fabricated and subjected to charging and discharging experiments. The analysis of the transients shows that several time constants are governing the charge dynamics, one of them is related to the resistivity-permittivity product of the dielectric.
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85.85.+j Micro- and nano-electromechanical systems (MEMS/NEMS) and devices
84.32.Dd Connectors, relays, and switches

Enhanced light emission from one-layered organic light-emitting devices doped with organic salt by simultaneous thermal and electrical annealing

Youn Chan Yim, Jin Ho Park, Sun Woong Kim, Eun Ha Choi, Guang Sup Cho, Yoon Ho Seo, Seung Oun Kang, Byoungchoo Park, Sang Hee Cho, In Tae Kim, S. H. Han, Jongsun Lim, and Hideo Takezoe

Appl. Phys. Lett. 89, 103507 (2006); http://dx.doi.org/10.1063/1.2345375 (3 pages) | Cited 6 times

Online Publication Date: 6 September 2006

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The authors studied the effect of thermal and electrical annealing on light emission of fluorescent one-layered organic light-emitting devices (OLEDs) doped with organic salts. From the annealed OLEDs, we clearly observed homogeneous and enhanced electroluminescent (EL) emission over the whole active area with fast responses. Moreover, improved efficiency was also observed from annealed phosphorescent OLEDs. These improved EL characteristics indicate that simultaneous annealing can induce proper adsorption of charged salt ions at the electrode surfaces, leading to enhanced electroluminescence of one-layered OLEDs due to increased and balanced injection of carriers.
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85.60.Jb Light-emitting devices

Punchthrough effects on the electrostatic discharge robustness of ultrathin silicon films on insulator devices

Jam-Wem Lee and Howard Tang

Appl. Phys. Lett. 89, 103508 (2006); http://dx.doi.org/10.1063/1.2345377 (3 pages) | Cited 4 times

Online Publication Date: 6 September 2006

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Physical mechanisms that dominate the electrostatic discharge (ESD) robustness of silicon-on-insulator (SOI) devices are theoretically and experimentally investigated here. The authors experimentally find that the ESD robustness depends strongly on the device geometry correlated turn on mechanism. Moreover, the punchthrough mechanism is theoretically demonstrated to be the unsuitable turn on mechanism that causes a nonuniform current distribution and a low ESD strength. The punchthrough mechanism, according to their theoretical analysis, will occur in scaled down structure and reduce the benefits arising from sizing down. Therefore, optimization of a device structure is necessary to prevent nanoscaled SOI devices from the punchthrough induced ESD robustness degradation.
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85.30.Tv Field effect devices

Bias polarity dependent data retention of resistive random access memory consisting of binary transition metal oxide

K. Kinoshita, T. Tamura, M. Aoki, Y. Sugiyama, and H. Tanaka

Appl. Phys. Lett. 89, 103509 (2006); http://dx.doi.org/10.1063/1.2339032 (3 pages) | Cited 89 times

Online Publication Date: 6 September 2006

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The authors investigated the data retention properties of NiOy resistors exposed to sputtered particles and found that they depended on the bias polarity used to program the data. Only the data in the high resistance state programmed by applying positive bias to the top electrode were easily damaged. This suggests that the “reset” process can take place when the anodic side of the conductive filaments, which were formed during the “forming” process, is insulated. In addition, the data retention test for thermal stress suggests that the reset process can take place thermally.
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84.30.Sk Pulse and digital circuits
84.32.Ff Conductors, resistors (including thermistors, varistors, and photoresistors)

Study of hole concentration of 1,4-bis[N-(1-naphthyl)-N′-phenylamino]-4,4′ diamine doped with tungsten oxide by admittance spectroscopy

Ming-Ta Hsieh, Chan-Ching Chang, Jenn-Fang Chen, and Chin H. Chen

Appl. Phys. Lett. 89, 103510 (2006); http://dx.doi.org/10.1063/1.2345610 (3 pages) | Cited 21 times

Online Publication Date: 6 September 2006

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The effect of tungsten oxide (WO3) incorporation into 1,4-bis[N-(1-naphthyl)-N′-phenylamino]-4,4′ diamine (NPB) layer is investigated in NPB-tris(8-hydroxyquinoline)aluminium heterojunction organic light-emitting diodes. The admittance spectroscopy studies show that increasing the WO3 volume percentage from 0% to 16% can increase the hole concentration of the NBP layer from 1.97×1014 to 1.90×1017 cm−3 and decrease the activation energy of the resistance of the NPB layer from 0.354 to 0.176 eV. Thus, this incorporation reduces the Ohmic loss and increases the band bending in the NBP layer near the interface, resulting in an improved hole injection via tunneling through a narrow depletion region.
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72.20.Fr Low-field transport and mobility; piezoresistance
73.40.Lq Other semiconductor-to-semiconductor contacts, p-n junctions, and heterojunctions
61.72.uf Ge and Si
85.60.Jb Light-emitting devices
73.40.Gk Tunneling

Highly efficient and color-tuning electrophosphorescent devices based on CuI complex

Guangbo Che, Zisheng Su, Wenlian Li, Bei Chu, Mingtao Li, Zhizhi Hu, and Zhiqiang Zhang

Appl. Phys. Lett. 89, 103511 (2006); http://dx.doi.org/10.1063/1.2345826 (3 pages) | Cited 45 times

Online Publication Date: 6 September 2006

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Highly efficient electrophosphorescence from organic light-emitting devices based on a CuI complex, [Cu(DPEphos)(Dicnq)]BF4 (DPEphos = bis[2-(diphenylphosphino)phenyl]ether and Dicnq = 6,7-Dicyanodipyrido[2,2-d:2′,3′-f] quinoxaline), doped into 4,4′-N,N′-dicarbazole-biphenyl is demonstrated. The performances of these devices fabricated by vacuum vapor deposition technique are among the best reported for devices incorporating CuI complexes as emitters. A low turn-on voltage of 4 V, a maximum current efficiency up to 11.3 cd/A, and a peak brightness of 2322 cd/m2 were achieved, respectively. The phosphorescent operating mechanism of organic light-emitting devices based on CuI complex was discussed. Electroluminescent colors can be tuned ranging from green-yellow to orange-red region, and its band tail at longer wavelength can cover near infrared.
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85.60.Jb Light-emitting devices
81.15.-z Methods of deposition of films and coatings; film growth and epitaxy

Effect of space charge polarization in radio frequency microelectromechanical system capacitive switch dielectric charging

G. J. Papaioannou, M. Exarchos, V. Theonas, J. Psychias, G. Konstantinidis, D. Vasilache, A. Muller, and D. Neculoiu

Appl. Phys. Lett. 89, 103512 (2006); http://dx.doi.org/10.1063/1.2347278 (3 pages) | Cited 4 times

Online Publication Date: 6 September 2006

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The letter presents the investigation of the temperature dependence of the charging mechanism of dielectric layer in radio frequency microelectromechanical system switch. The accumulated charge kinetics are monitored through the transient response of device capacitance when a bias greater than pull-in is applied. The capacitance transient response is shown to follow a stretched exponential law. The “time scale” of the stretched exponential process is found to be thermally activated, with an activation energy that is determined from Arrhenius plot.
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85.85.+j Micro- and nano-electromechanical systems (MEMS/NEMS) and devices
84.32.Dd Connectors, relays, and switches

Voltage tunable surface acoustic wave phase shifter using semiconducting/piezoelectric ZnO dual layers grown on r-Al2O3

Jun Zhu, Ying Chen, Gaurav Saraf, Nuri W. Emanetoglu, and Yicheng Lu

Appl. Phys. Lett. 89, 103513 (2006); http://dx.doi.org/10.1063/1.2347695 (3 pages) | Cited 8 times

Online Publication Date: 7 September 2006

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A voltage tunable surface acoustic wave phase shifter is made of a ZnO based semiconducting/piezoelectric dual-layer structure on an r-Al2O3 substrate by using a hybrid growth technology. Piezoelectric and semiconducting ZnO layers are used for acoustic wave excitation and n-type conducting channel, while SiO2 serves as the gate insulator. The acoustic velocity of the device is tuned by changing the n-channel conductance with a dc bias. The in-plane anisotropy of the piezoelectric ZnO/r-Al2O3 structure enables multimode operations. Sezawa and Love wave modes are used to get high effective coupling coefficients, which result in large phase shifts.
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85.50.-n Dielectric, ferroelectric, and piezoelectric devices
84.30.Qi Modulators and demodulators; discriminators, comparators, mixers, limiters, and compressors

Analysis and control of the active area scaling effect on white organic light emitting diodes towards lighting applications

C. Piliego, M. Mazzeo, M. Salerno, R. Cingolani, G. Gigli, and A. Moro

Appl. Phys. Lett. 89, 103514 (2006); http://dx.doi.org/10.1063/1.2347698 (3 pages) | Cited 11 times

Online Publication Date: 7 September 2006

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The authors investigate the scaling of the performances on white organic light emitting diode in devices having active regions ranging from 0.25 to 9 cm2. They observe a drop in the luminance and in the current density with increasing active area of the devices. A model where both these effects are ascribed to the spread of the current leakage on the indium tin oxide surface is proposed. To limit the consequences of these effects on the device performances, they insert a pattern of metal stripes onto the anode contact. This results in a device with a maximum luminance of 1800 cd/m2 on a surface of 9 cm2.
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85.60.Jb Light-emitting devices

Improving the stability of organic light-emitting devices by using a thin Mg anode buffer layer

Hany Aziz, Yichun Luo, Gu Xu, and Zoran D. Popovic

Appl. Phys. Lett. 89, 103515 (2006); http://dx.doi.org/10.1063/1.2345242 (3 pages) | Cited 8 times

Online Publication Date: 7 September 2006

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Introducing a thin Mg layer at the hole injection contact of organic light-emitting devices remarkably improves their operational stability. Devices in which a ∼ 2.5 nm thick Mg layer is inserted between the indium tin oxide anode and a tetrafluoro-tetracyanoquinodimethane-doped hole transport material layer exhibit a significantly longer lifetime compared to similar devices without the Mg layer. After 600 h of operation at a current density of 62.5 mA/cm2 with a 50% duty cycle, the luminance of devices containing the Mg layer decreases by only ∼ 10% of the initial value. The stability enhancement resulting from using the Mg layer is attributed to improved balance in charge injection at the anode and cathode contacts.
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85.60.Jb Light-emitting devices

Electric tempest in a teacup: The tea leaf analogy to microfluidic blood plasma separation

Leslie Y. Yeo, James R. Friend, and Dian R. Arifin

Appl. Phys. Lett. 89, 103516 (2006); http://dx.doi.org/10.1063/1.2345590 (3 pages) | Cited 10 times

Online Publication Date: 7 September 2006

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In a similar fashion to Einstein’s tea leaf paradox, the rotational liquid flow induced by ionic wind above a liquid surface can trap suspended microparticles by a helical motion, spinning them down towards a bottom stagnation point. The motion is similar to Batchelor [Q. J. Mech. Appl. Math. 4, 29 (1951)] flows occurring between stationary and rotating disks and arises due to a combination of the primary azimuthal and secondary bulk meridional recirculation that produces a centrifugal and enhanced inward radial force near the chamber bottom. The technology is thus useful for microfluidic particle trapping/concentration; the authors demonstrate its potential for rapid erythrocyte/blood plasma separation for miniaturized medical diagnostic kits.
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87.80.-y Biophysical techniques (research methods)
87.17.-d Cell processes
47.85.Np Fluidics
47.32.Ef Rotating and swirling flows
47.65.-d Magnetohydrodynamics and electrohydrodynamics
47.60.-i Flow phenomena in quasi-one-dimensional systems

Bias-crafted magnetic tunnel junctions with bistable spin-dependent states

M. Bowen, J.-L. Maurice, A. Barthélémy, P. Prod’homme, E. Jacquet, J.-P. Contour, D. Imhoff, and C. Colliex

Appl. Phys. Lett. 89, 103517 (2006); http://dx.doi.org/10.1063/1.2345592 (3 pages) | Cited 11 times

Online Publication Date: 7 September 2006

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The authors have observed stable, reversible two-resistance states with substantial tunneling magnetoresistances of opposite signs in La0.7Sr0.3MnO3/SrTiO3/Co1−xCrx junctions. Electron energy loss spectroscopy studies reveal the segregation and oxidation of electrochemically reactive chromium at that interface, resulting in oxygen vacancies in the oxide barrier. Bias-induced switching between the two junction states is argued to reflect the incidence of these barrier defects at and near the electrically unstable SrTiO3/Co1−xCrx interface. This affirms bias crafting as an additional lever in spintronic research across semiconducting spacers.
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75.70.Cn Magnetic properties of interfaces (multilayers, superlattices, heterostructures)
75.47.-m Magnetotransport phenomena; materials for magnetotransport
75.60.-d Domain effects, magnetization curves, and hysteresis
64.75.-g Phase equilibria
81.65.Mq Oxidation

Optofluidic third order distributed feedback dye laser

Morten Gersborg-Hansen and Anders Kristensen

Appl. Phys. Lett. 89, 103518 (2006); http://dx.doi.org/10.1063/1.2345602 (3 pages) | Cited 22 times

Online Publication Date: 7 September 2006

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This letter describes the design and operation of a polymer-based third order distributed feedback (DFB) microfluidic dye laser. The device relies on light confinement in a nanostructured polymer film where an array of nanofluidic channels is filled by capillary action with a liquid dye solution which has a refractive index lower than that of the polymer. In combination with a third order DFB grating, formed by the array of nanofluidic channels, this yields a low threshold for lasing. The laser is straightforward to integrate on lab-on-a-chip microsystems where coherent, tunable light in the visible range is desired.
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42.55.Mv Dye lasers
42.60.By Design of specific laser systems
85.85.+j Micro- and nano-electromechanical systems (MEMS/NEMS) and devices
47.85.Np Fluidics
42.82.Bq Design and performance testing of integrated-optical systems

Observation of a multilayer planar in-grown stacking fault in 4H-SiC p-i-n diodes

Joshua D. Caldwell, P. B. Klein, Mark E. Twigg, Robert E. Stahlbush, Orest J. Glembocki, Kendrick X. Liu, Karl D. Hobart, and Fritz Kub

Appl. Phys. Lett. 89, 103519 (2006); http://dx.doi.org/10.1063/1.2346135 (3 pages) | Cited 6 times

Online Publication Date: 7 September 2006

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In-grown stacking faults (IGSFs) are planar defects that do not propagate under either an applied optical or electrical bias; however, their effect upon the electrical characteristics of diodes is not well understood. We present evidence for a multilayered IGSF and discuss its electrical and optical characteristics. These IGSFs, despite similar electroluminescence signatures, were observed to act as either a current barrier or as a short between the p+ and n+ layers, causing increases in the leakage current in p-i-n diodes. The difference in conduction behavior is attributed to the nucleation location of the IGSF within the diode drift region.
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85.30.Kk Junction diodes

Metal Schottky diodes on Zn-polar and O-polar bulk ZnO

M. W. Allen, M. M. Alkaisi, and S. M. Durbin

Appl. Phys. Lett. 89, 103520 (2006); http://dx.doi.org/10.1063/1.2346137 (3 pages) | Cited 46 times

Online Publication Date: 7 September 2006

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Planar Pd, Pt, Au, and Ag Schottky diodes with low ideality factors were fabricated on the Zn-polar (0001) and O-polar (000math) faces of bulk, single crystal ZnO wafers. The diodes were characterized by current-voltage and capacitance-voltage measurements. A polarity effect was observed for Pt and Pd diodes with higher quality barriers achieved on the O-polar face. No significant polarity effect was observed for Au or Ag diodes. The highest barriers were achieved with Ag as the Schottky metal with barrier heights varying between 0.77 and 1.02 eV. This is possibly due to varying degrees of oxidation of the Ag contacts.
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85.30.Kk Junction diodes
85.30.Hi Surface barrier, boundary, and point contact devices

Model to determine the self-resonant frequency of micromachined spiral inductors

C. C. Chen, Cheng-De Lin, and Y. T. Cheng

Appl. Phys. Lett. 89, 103521 (2006); http://dx.doi.org/10.1063/1.2346371 (3 pages)

Online Publication Date: 7 September 2006

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This letter presents an approach to characterize electron behaviors within polygonal micromachined spiral inductors in which self-resonance occurs. Combining with the concepts of anomalous dispersion, standing wave, and field scattering, the self-resonant frequency of the microinductors can be calculated by means of an associated analytical model. According to this model the self-resonant frequency (SRF) can be derived as the “free electron” frequency of the inductor material. Simulation and measurement results validate that the model can provide a satisfactory prediction to the SRF of polygonal micromachined spiral inductors.
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84.32.Hh Inductors and coils; wiring
41.20.Jb Electromagnetic wave propagation; radiowave propagation

Voltage drop in an (AlxGa1−x)0.5In0.5P light-emitting diode probed by Kelvin probe force microscopy

Kl.-D. Katzer, W. Mertin, G. Bacher, A. Jaeger, and K. Streubel

Appl. Phys. Lett. 89, 103522 (2006); http://dx.doi.org/10.1063/1.2347184 (3 pages) | Cited 6 times

Online Publication Date: 7 September 2006

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The authors report on quantitative investigations of the voltage drop across the heterostructure layer sequence of an operating AlGaInP light-emitting diode via Kelvin probe force microscopy for different external biases between −2.0 and +1.86 V. In the low voltage regime, most of the voltage drops in the active layer. For bias voltages above +1.5 V, however, they found an additional voltage drop on the p side of the device, which reduces the power efficiency of the light-emitting diode.
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85.60.Jb Light-emitting devices

High permittivity quaternary metal (HfTaTiOx) oxide layer as an alternative high-κ gate dielectric

Hong-Jyh Li, J. Price, Mark Gardner, Nan Lu, and Dim-Lee Kwong

Appl. Phys. Lett. 89, 103523 (2006); http://dx.doi.org/10.1063/1.2347281 (3 pages) | Cited 5 times

Online Publication Date: 7 September 2006

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The authors investigated the optical and electrical properties of the high permittivity (κ) metal oxides, HfTiO and HfTaTiO, using HfO2 as a reference and compared their material properties against their electrical performance. HfTiO has a higher κ value but its band offset is relatively smaller and, therefore, it has greater gate leakage current than HfO2. HfTaTiO has an even higher κ value which compensates for the impact of its small band offset. In addition, HfO2 was found to have more defect states than the other two films, which caused a larger hysteresis in the capacitance-voltage scan and degraded channel mobility.
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77.84.Bw Elements, oxides, nitrides, borides, carbides, chalcogenides, etc.
77.55.-g Dielectric thin films
77.22.Ch Permittivity (dielectric function)
77.80.Dj Domain structure; hysteresis
71.55.Ht Other nonmetals

Bulk heterojunction organic photovoltaic devices based on phenyl-cored thiophene dendrimers

Nikos Kopidakis, William J. Mitchell, Jao van de Lagemaat, David S. Ginley, Garry Rumbles, Sean E. Shaheen, and William L. Rance

Appl. Phys. Lett. 89, 103524 (2006); http://dx.doi.org/10.1063/1.2337859 (3 pages) | Cited 58 times

Online Publication Date: 8 September 2006

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Bulk heterojunction organic photovoltaic devices have been fabricated by blending phenyl-cored thiophene dendrimers with a fullerene derivative. A power conversion efficiency of 1.3% under simulated AM1.5 illumination is obtained for a four-arm dendrimer, despite its large optical band gap of 2.1 eV. The devices exhibit an increase in short-circuit current and power conversion efficiency as the length of the arm is increased. The fill factors of the devices studied are characteristically low, which is attributed to overly uniform mixing of the blend.
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85.60.-q Optoelectronic devices

Metal-insulator-semiconductor-type organic light-emitting transistor on plastic substrate

Kenji Nakamura, Takuya Hata, Atsushi Yoshizawa, Katsunari Obata, Hiroyuki Endo, and Kazuhiro Kudo

Appl. Phys. Lett. 89, 103525 (2006); http://dx.doi.org/10.1063/1.2347152 (3 pages) | Cited 6 times

Online Publication Date: 8 September 2006

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The authors report the characteristics of novel metal-insulator-semiconductor-type organic light-emitting transistors (MIS-OLETs). The drain current and luminescent intensity of the MIS-OLET can be controlled by changing hole injection carriers by applying a gate bias voltage. In addition, the high performance (400 cd/m2 at VD = −8 V) of MIS-OLETs fabricated on a plastic substrate as well as on a glass substrate is demonstrated and described.
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85.30.Tv Field effect devices
85.60.Jb Light-emitting devices
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