APL Nameplate
  • Volume/Page
  • Keyword
  • DOI
  • Citation
  • Advanced
   
 
 
 

Flickr Twitter iResearch App Facebook

BROWSE VOLUMES

Year Range: 
Search Issue | RSS Feeds RSS
Previous Issue Next Issue

4 Apr 2005

Volume 86, Issue 14, Articles (14xxxx)

Issue Cover Spotlight Figure

Appl. Phys. Lett. 86, 142101 (2005); http://dx.doi.org/10.1063/1.1895476 (3 pages)

M. Hanke, T. Boeck, A.-K. Gerlitzke, F. Syrowatka, F. Heyroth, and R. Köhler
Enlarge Image | Read More
Return to All Sections
back to top
RSS Feeds

Efficiency enhancement of an organic light-emitting diode with a cathode forming two-dimensional periodic hole array

C. Liu, V. Kamaev, and Z. V. Vardeny

Appl. Phys. Lett. 86, 143501 (2005); http://dx.doi.org/10.1063/1.1895481 (3 pages) | Cited 53 times

Online Publication Date: 28 March 2005

Full Text: Read Online (HTML) | Download PDF

Show Abstract
We fabricated an organic light-emitting diode using a π-conjugated polymer emissive layer sandwiched between two semitransparent electrodes: an optically thin gold film anode, whereas the cathode was in the form of an optically thick aluminum (Al) film with patterned periodic subwavelength two-dimensional hole array that showed anomalous transmission in the spectral range of the polymer photoluminescence band. At similar current densities, we obtained a sevenfold electroluminescence efficiency enhancement with the patterned Al device compared with a control device based on unperforated Al electrode.
Show PACS
85.60.Jb Light-emitting devices
78.60.Fi Electroluminescence
81.15.Lm Liquid phase epitaxy; deposition from liquid phases (melts, solutions, and surface layers on liquids)
78.55.Kz Solid organic materials
78.66.Qn Polymers; organic compounds
81.16.-c Methods of micro- and nanofabrication and processing
68.55.A- Nucleation and growth

Self-heated fiber Bragg grating sensors

Kevin P. Chen, Ben McMillen, Michael Buric, Chuck Jewart, and Wei Xu

Appl. Phys. Lett. 86, 143502 (2005); http://dx.doi.org/10.1063/1.1895485 (3 pages) | Cited 10 times

Online Publication Date: 28 March 2005

Full Text: Read Online (HTML) | Download PDF

Show Abstract
This letter demonstrates an approach for tuning fiber Bragg grating sensors with optical energy carried in the same optical fiber. Optical energy carried in the optical fiber was used to heat in-fiber Bragg gratings in order to alter the grating’s optical response to surrounding media. The functional enhancement of optically heated Bragg gratings as sensor devices is demonstrated by a dual-function Bragg grating temperature and level sensing array for liquid at room and cryogenic temperatures.
Show PACS
42.81.Pa Sensors, gyros
42.79.Dj Gratings

Hybrid light-emitting polymer device fabricated on a metallic nanowire array

A. E. Strevens, A. Drury, S. M. Lipson, M. Kröll, W. J. Blau, and H. H. Hörhold

Appl. Phys. Lett. 86, 143503 (2005); http://dx.doi.org/10.1063/1.1891297 (3 pages) | Cited 5 times

Online Publication Date: 28 March 2005

Full Text: Read Online (HTML) | Download PDF

Show Abstract
An electrode comprised of a copper nanowire array, fabricated by electrodeposition into a porous alumina membrane, is incorporated into a single-layer organic light-emitting device. The 48-nm-diameter copper nanowires form an array of electrical nanocontacts. Current–voltage and electroluminescence data for this device type are presented and compared with an equivalent planar copper electrode device. The nanowire array electrode device sustained a higher operating current density. The results show that such an array electrode can be used to inject charge in a polymer light-emitting diode, opening up the possibility of producing arrays of nanosized light sources using this approach.
Show PACS
85.60.Jb Light-emitting devices
85.35.-p Nanoelectronic devices
81.15.Pq Electrodeposition, electroplating
78.60.Fi Electroluminescence
73.63.Rt Nanoscale contacts

Measurement of single electron spin with submicron Hall magnetometer

Jinshuang Jin and Xin-Qi Li

Appl. Phys. Lett. 86, 143504 (2005); http://dx.doi.org/10.1063/1.1895484 (3 pages) | Cited 9 times

Online Publication Date: 30 March 2005

Full Text: Read Online (HTML) | Download PDF

Show Abstract
Submicron Hall magnetometry has been demonstrated as an efficient technique to probe extremely weak magnetic fields. In this letter, we analyze the possibility of employing it to detect single electron spin. Signal strength and readout time are estimated and discussed with respect to a number of practical issues.
Show PACS
07.55.Jg Magnetometers for susceptibility, magnetic moment, and magnetization measurements
85.30.Fg Bulk semiconductor and conductivity oscillation devices (including Hall effect devices, space-charge-limited devices, and Gunn effect devices)
75.30.Cr Saturation moments and magnetic susceptibilities

Gate current leakage and breakdown mechanism in unpassivated AlGaN/GaN high electron mobility transistors by post-gate annealing

Hyeongnam Kim, Jaesun Lee, Dongmin Liu, and Wu Lu

Appl. Phys. Lett. 86, 143505 (2005); http://dx.doi.org/10.1063/1.1899255 (3 pages) | Cited 15 times

Online Publication Date: 30 March 2005

Full Text: Read Online (HTML) | Download PDF

Show Abstract
Gate leakage/breakdown mechanism in unpassivated AlGaN/GaN high electron mobility transistors (HEMTs) is investigated by performing temperature-dependent pulsed current–voltage (I–V) and current transient measurements of AlGaN/GaN HEMTs without and with annealing after Schottky gate formation. After post-gate annealing, the devices exhibited significantly smaller gate leakage current and higher breakdown voltage even without any gate dielectrics or passivation layer. The temperature-dependent current transient measurements show that the current dispersion in the unannealed HEMTs is attributed to traps with an emission time constant (tE) of ∼ 0.5 μs at 295 K and an activation energy of ∼ 38 meV. On the contrary, the 20-min annealed devices have traps with tE of 21.6 μs at 295 K and an activation energy of ∼ 0.31 eV. The results suggest that the post-gate annealing removes shallow traps, and creates or activates deeper traps. We propose that the breakdown and gate leakage current is mainly due to the emission current from shallow traps in unpassivated AlGaN/GaN HEMTs. The breakdown voltage improvement after the post-gate annealing is due to the removal of shallow traps near the Schottky gate metal/AlGaN interface.
Show PACS
85.30.Tv Field effect devices
61.72.Cc Kinetics of defect formation and annealing
73.50.Gr Charge carriers: generation, recombination, lifetime, trapping, mean free paths
73.20.Hb Impurity and defect levels; energy states of adsorbed species
68.55.Ln Defects and impurities: doping, implantation, distribution, concentration, etc.

Temperature dependence of the negative bias temperature instability in the framework of dispersive transport

B. Kaczer, V. Arkhipov, R. Degraeve, N. Collaert, G. Groeseneken, and M. Goodwin

Appl. Phys. Lett. 86, 143506 (2005); http://dx.doi.org/10.1063/1.1897046 (3 pages) | Cited 13 times

Online Publication Date: 31 March 2005

Full Text: Read Online (HTML) | Download PDF

Show Abstract
Negative bias temperature instability (NBTI) is studied in multiple-gate field-effect transistors with an ultrathin gate oxide. It is observed that the threshold voltage shift in these devices follows a power-law function of time, with the exponent depending linearly on temperature. An analytic model is proposed that explains this temperature dependence by dispersive diffusion of hydrogen in the bulk of the gate oxide. Based on both the experimental data and the model, it is concluded that NBTI is an inherently non-Arrhenius process.
Show PACS
81.40.Gh Other heat and thermomechanical treatments
81.70.Pg Thermal analysis, differential thermal analysis (DTA), differential thermogravimetric analysis

First-principles studies of the intrinsic effect of nitrogen atoms on reduction in gate leakage current through Hf-based high-k dielectrics

N. Umezawa, K. Shiraishi, T. Ohno, H. Watanabe, T. Chikyow, K. Torii, K. Yamabe, K. Yamada, H. Kitajima, and T. Arikado

Appl. Phys. Lett. 86, 143507 (2005); http://dx.doi.org/10.1063/1.1899232 (3 pages) | Cited 57 times

Online Publication Date: 31 March 2005

Full Text: Read Online (HTML) | Download PDF

Show Abstract
The atomistic effects of N atoms on the leakage current through HfO2 high-k gate dielectrics have been studied from first-principles calculations within the framework of a generalized gradient approximation (GGA). It has been found that the intrinsic effects of N atoms drastically reduce the electron leakage current. N atoms couple favorably with oxygen vacancies (VO) in HfO2 and extract electrons from VO. As a result, VO energy levels are drastically elevated due to the charged-state change in VO from neutral (VO0) to positively charged (VO2+). Accordingly, N incorporation removes the electron leakage path mediated by VO related gap states.
Show PACS
77.22.-d Dielectric properties of solids and liquids

Surface roughness in sulfur ion-implanted InP with molecular beam epitaxy regrown double-heterojunction bipolar transistor layers

Ting-Chen Hu, M. F. Chang, Nils Weimann, Jianxin Chen, and Young-Kai Chen

Appl. Phys. Lett. 86, 143508 (2005); http://dx.doi.org/10.1063/1.1891270 (3 pages) | Cited 1 time

Online Publication Date: 31 March 2005

Full Text: Read Online (HTML) | Download PDF

Show Abstract
We report on deep ion-implantation of sulfur into InP substrates to replace the epitaxial subcollector layer of double-heterojunction bipolar transistors. Using optimized implantation conditions of 350 keV energy and 1×1015 cm−2 dose, we achieved a subcollector sheet resistance of 15 Ω/square. Under well-controlled regrowth conditions a root-mean-square roughness of 12 Å is measured from DHBT epitaxial layers grown on implanted InP substrates, comparable to DHBT epitaxial layers grown on n+ epiready unimplanted substrates. We observe a pronounced increase in surface roughness of epitaxial layer beyond a threshold ion dose, depending on implantation energy. Large-area DHBT devices result with sulfur-ion implanted subcollector shows similar characteristics compared to devices fabricated on n+-doped InP substrates.
Show PACS
85.30.Pq Bipolar transistors
61.72.uj III-V and II-VI semiconductors
68.35.B- Structure of clean surfaces (and surface reconstruction)
81.15.Hi Molecular, atomic, ion, and chemical beam epitaxy
73.20.At Surface states, band structure, electron density of states
68.55.Ln Defects and impurities: doping, implantation, distribution, concentration, etc.
68.55.A- Nucleation and growth
68.55.-a Thin film structure and morphology

Fullerene-doped hole transport molecular films for organic light-emitting diodes

Y. Yuan, D. Grozea, and Z. H. Lu

Appl. Phys. Lett. 86, 143509 (2005); http://dx.doi.org/10.1063/1.1899241 (3 pages) | Cited 14 times

Online Publication Date: 1 April 2005

Full Text: Read Online (HTML) | Download PDF

Show Abstract
C60-doped N,N′-bis(l-naphthyl)-N, N′-diphenyl-1, 1′-biphenyl-4, 4′-diamine(NPB) film is studied as hole injection layer between indium tin oxide (ITO) and NPB. The doped films on ITO substrates were found to be thermally stable after being annealed at temperatures up to 120 °C. This was attributed to a strong interaction between NPB and C60 providing a dipole force crosslinking NPB molecules, similar to a crosslinked thermoset polymer networks. Furthermore, the C60-doped NPB p-type hole injection layers yield devices having better efficiency and low driving voltage as compared with standard devices with CuPc as the hole injection layers.
Show PACS
85.60.Jb Light-emitting devices
73.61.Ph Polymers; organic compounds
73.50.Dn Low-field transport and mobility; piezoresistance
61.72.Cc Kinetics of defect formation and annealing
61.48.-c Structure of fullerenes and related hollow and planar molecular structures
68.55.-a Thin film structure and morphology
85.65.+h Molecular electronic devices
68.60.Dv Thermal stability; thermal effects

Near- and far-infrared p‐GaAs dual-band detector

G. Ariyawansa, M. B. M. Rinzan, D. G. Esaev, S. G. Matsik, G. Hastings, A. G. U. Perera, H. C. Liu, B. N. Zvonkov, and V. I. Gavrilenko

Appl. Phys. Lett. 86, 143510 (2005); http://dx.doi.org/10.1063/1.1899242 (3 pages) | Cited 10 times

Online Publication Date: 1 April 2005

Full Text: Read Online (HTML) | Download PDF

Show Abstract
A dual-band homojunction interfacial workfunction internal photoemission infrared detector that responds in both near- and far-infrared (NIR and FIR) regions is reported. In the p+‐i‐p+ detector structure, the emitter is carbon doped to 1.5×1019 cm−3, and a 1 μm thick GaAs layer acts as the barrier, followed by another highly p-doped GaAs contact layer. The NIR response is due to the interband transition in GaAs barrier layer and the threshold wavelength observed at 0.82 μm is in good agreement with the 1.51 eV band gap of GaAs at 4.2 K. The intraband transition giving rise to FIR response is observed up to 70 μm. Interband responsivity was (under 100 mV reverse bias at 20 K) ∼ 8 A/W at 0.8 μm, while the intraband responsivity was ∼ 7 A/W. The detector has peak detectivities D* ∼ 6×109 and 5×109 cm Hz1/2/W at 0.8 and 57 μm wavelengths, respectively, under 100 mV reverse bias at 20 K.
Show PACS
85.60.Gz Photodetectors (including infrared and CCD detectors)
07.57.Kp Bolometers; infrared, submillimeter wave, microwave, and radiowave receivers and detectors

Ohmic cathode for low-voltage organic light-emitting diodes

X. D. Feng, C. J. Huang, V. Lui, R. S. Khangura, and Z. H. Lu

Appl. Phys. Lett. 86, 143511 (2005); http://dx.doi.org/10.1063/1.1899766 (3 pages) | Cited 29 times

Online Publication Date: 1 April 2005

Full Text: Read Online (HTML) | Download PDF

Show Abstract
It is found that voltage-current characteristics of Al/C60 interfaces are fundamentally altered from a strong rectifying junction to an Ohmic junction where a LiF interlayer is used. Al/LiF/C60 has been used as an Ohmic cathode for organic light-emitting diode (OLED). The Ohmic cathode together with a high electron mobility of the fullerene layer have lead to a drastic reduction in the driving voltage and consequently a significant increase in the power efficiency of OLED.
Show PACS
85.60.Jb Light-emitting devices

High-power AlGaN/InGaN/AlGaN/GaN recessed gate heterostructure field-effect transistors

R. S. Qhalid Fareed, X. Hu, A. Tarakji, J. Deng, R. Gaska, M. Shur, and M. A. Khan

Appl. Phys. Lett. 86, 143512 (2005); http://dx.doi.org/10.1063/1.1886902 (3 pages) | Cited 6 times

Online Publication Date: 1 April 2005

Full Text: Read Online (HTML) | Download PDF

Show Abstract
We demonstrate the use of high-quality thin InGaN films as the reactive ion etching (RIE) stop layer for fabrication of recessed gate high-microwave-power AlGaN/InGaN/AlGaN/GaN heterostructure field-effect transistors. We used migration-enhanced-metalorganic-chemical-vapor-deposition grown InGaN layer sandwiched in AlGaN barrier yields better than 10 times RIE selectivity of AlGaN and InGaN compared to our conventional standard AlGaN/GaN high electron mobility transistors. The fabricated devices exhibited a 50% increase in the breakdown voltage, which is attributed primarily due to the improved electric field distribution at the gate edge and to the increased distance between the AlGaN surface and the device channel. The continuous wave microwave power was measured at the drain bias as high as 60 V. The maximum output power and power added efficiency were 8.9 W/mm and 40%, respectively. The obtained results demonstrate a potential of this technique for development of the next-generation high-power transistors.
Show PACS
85.30.Tv Field effect devices
84.30.Jc Power electronics; power supply circuits
84.40.-x Radiowave and microwave (including millimeter wave) technology
81.15.Gh Chemical vapor deposition (including plasma-enhanced CVD, MOCVD, ALD, etc.)
81.65.Cf Surface cleaning, etching, patterning
73.40.Kp III-V semiconductor-to-semiconductor contacts, p-n junctions, and heterojunctions
81.15.Kk Vapor phase epitaxy; growth from vapor phase

Ambipolar organic field-effect transistor using gate insulator hysteresis

Eriko Mizuno, Masateru Taniguchi, and Tomoji Kawai

Appl. Phys. Lett. 86, 143513 (2005); http://dx.doi.org/10.1063/1.1899773 (3 pages) | Cited 8 times

Online Publication Date: 1 April 2005

Full Text: Read Online (HTML) | Download PDF

Show Abstract
An organic field-effect transistor based on a copper-phthalocyanine and cyanoethylpullulan gate insulator showed ambipolar operation using gate insulator hysteresis, which appeared at less than 1 mHz. The gate insulator possesses spontaneous polarization of 1.6 μC/cm2 and a coercive electric field of 50 kV/cm. After poling in an effort to obtain a large amount of accumulated charge, the field-effect mobilities of the hole and electron were 4.1×10−3 and 3.5×10−6 cm2/Vs, respectively. The on∕off ratio at VSG = ±10 V was 6×104 for the p type and 70 for the n type.
Show PACS
85.30.Tv Field effect devices
77.22.Ej Polarization and depolarization
77.80.Dj Domain structure; hysteresis

Stacked metal cathode for high-contrast-ratio polymeric light-emitting devices

S. H. Li, H. Liem, C. W. Chen, E. H. Wu, Z. Xu, and Y. Yang

Appl. Phys. Lett. 86, 143514 (2005); http://dx.doi.org/10.1063/1.1897440 (3 pages) | Cited 19 times

Online Publication Date: 1 April 2005

Full Text: Read Online (HTML) | Download PDF

Show Abstract
An extremely high optical absorbing film made of alternating aluminum–silver layers was used as cathode in polymeric light-emitting devices (PLEDs). Physical properties of the cathodes were characterized by I–V measurement, atomic force microscopy, and x-ray photoemission spectroscopy. As a result of the slow evaporation rate, each pair of the aluminum–silver layer was shown to be in the form of aluminum–aluminum oxide nanoclusters embedded in an amorphous charge conducting network of silver. The nanoclusters helped to absorb and scatter the ambient light effectively. The use of four alternating layers structure in conventional PLEDs demonstrated 126% enhancement of contrast under 1000 lx ambient illumination. The I–V characteristics of the black cathode PLEDs remained intact when compared with reference PLEDs. This technology offers precise control of the cathode quality in terms of its reflectivity and conductivity.
Show PACS
85.60.Jb Light-emitting devices
Return to All Sections
Close

Google Calendar

ADVERTISEMENT

Go to AIP Home   © AIP Publishing LLC
close