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

31 Jan 2005

Volume 86, Issue 5, Articles (05xxxx)

Issue Cover Spotlight Figure

Appl. Phys. Lett. 86, 052504 (2005); http://dx.doi.org/10.1063/1.1855413 (3 pages)

Sang-Koog Kim, Ki-Suk Lee, Byoung-Woo Kang, Kyung-Jin Lee, and J. B. Kortright
Enlarge Image | Read More
Return to All Sections
back to top
RSS Feeds

Role of growth conditions on magnetic properties of AlCrN grown by molecular beam epitaxy

R. M. Frazier, G. T. Thaler, J. Y. Leifer, J. K. Hite, B. P. Gila, C. R. Abernathy, and S. J. Pearton

Appl. Phys. Lett. 86, 052101 (2005); http://dx.doi.org/10.1063/1.1857074 (3 pages) | Cited 32 times

Online Publication Date: 25 January 2005

Full Text: Read Online (HTML) | Download PDF

Show Abstract
AlCrN layers were grown by gas source molecular beam epitaxy with varying amounts of Cr (up to ∼ 3 at. %) under a broad range of Cr cell temperatures and V/III ratio. Magnetic measurements performed in a superconducting quantum interference device magnetometer showed evidence of ferromagnetism up to 350 K in single phase material. Magnetization dependence on dopant cell temperature and V/III was used to optimize the growth conditions of the AlCrN layers. The single-phase material was highly insulating ( ∼ 1010 Ω cm), while the material containing second phases (predominantly Cr2N and AlxCry) was conducting with resistivity of order 1000 Ω cm. High resolution x-ray diffraction rocking curves indicated high crystalline quality in the single phase material.
Show PACS
75.50.Pp Magnetic semiconductors
75.50.Dd Nonmetallic ferromagnetic materials
75.70.Ak Magnetic properties of monolayers and thin films
73.61.Ey III-V semiconductors
81.15.Hi Molecular, atomic, ion, and chemical beam epitaxy
75.60.Ej Magnetization curves, hysteresis, Barkhausen and related effects
68.55.-a Thin film structure and morphology
68.55.Nq Composition and phase identification

Coulomb blockade directional coupler

P. Pingue, V. Piazza, F. Beltram, I. Farrer, D. A. Ritchie, and M. Pepper

Appl. Phys. Lett. 86, 052102 (2005); http://dx.doi.org/10.1063/1.1857078 (3 pages) | Cited 10 times

Online Publication Date: 26 January 2005

Full Text: Read Online (HTML) | Download PDF

Show Abstract
A tunable directional coupler based on Coulomb blockade effect is presented. Two electron waveguides are coupled by a quantum dot to an injector waveguide. Electron confinement is obtained by surface Schottky gates on a single GaAs/AlGaAs heterojunction. Magneto-electrical measurements down to 350 mK are presented and large transconductance oscillations are reported on both outputs up to 4.2 K. Experimental results are interpreted in terms of Coulomb blockade effect and the relevance of the present design strategy for the implementation of an electronic multiplexer is underlined.
Show PACS
85.35.Ds Quantum interference devices
85.35.Be Quantum well devices (quantum dots, quantum wires, etc.)
73.23.Hk Coulomb blockade; single-electron tunneling
75.80.+q Magnetomechanical effects, magnetostriction
73.40.Ns Metal-nonmetal contacts
73.30.+y Surface double layers, Schottky barriers, and work functions

Effect of low-temperature-grown GaN cap layer on reduced leakage current of GaN Schottky diodes

J. K. Sheu, M. L. Lee, and W. C. Lai

Appl. Phys. Lett. 86, 052103 (2005); http://dx.doi.org/10.1063/1.1861113 (3 pages) | Cited 19 times

Online Publication Date: 27 January 2005

Full Text: Read Online (HTML) | Download PDF

Show Abstract
In this study, GaN Schottky barrier diodes (SBDs) were grown by organometallic vapor phase epitaxy (OMVPE). It was found that we could significantly reduce reverse-bias leakage current by introducing a low-temperature-grown (LTG) GaN layer on top of the conventional GaN SBDs. The reduction has a factor of 3–4 in a typical GaN∕Ni∕Au SBD having LTG GaN cap layer. Atomic force microscopy showed that surface pits of threading dislocation (TD) termination did not almost observed as the LTG GaN cap layer was grown to be disposed on a typical high-temperature (HT) GaN layer. Therefore, this reduction in leakage current could be related to the reduction of surface pit densities of threading dislocation termination by using LTG GaN cap layers. This might be due to the suppression of surface states existing in the vicinity of TD terminations.
Show PACS
81.05.Bx Metals, semimetals, and alloys
81.15.Kk Vapor phase epitaxy; growth from vapor phase

Facile fabrication method for p/n-type and ambipolar transport polyphenylenevinylene-based thin-film field-effect transistors by blending C60 fullerene

Y. Hayashi, H. Kanamori, I. Yamada, A. Takasu, S. Takagi, and K. Kaneko

Appl. Phys. Lett. 86, 052104 (2005); http://dx.doi.org/10.1063/1.1861115 (3 pages) | Cited 20 times

Online Publication Date: 27 January 2005

Full Text: Read Online (HTML) | Download PDF

Show Abstract
We have demonstrated the solution-processed p- and n-type transports including ambipolar transport organic thin-film transistors (OTFTs), required for complementary thin-film integrated circuit technology, by a facile method of blending the n-type C60 and the p-type [poly(2-methoxy-5-[2’-ethyl-hexyloxy]-1,4-phenylene vinylene] (MEH-PPV). The carrier transport of PPV-based thin-film field-effect transistors with various C60 compositions are investigated by using the field-effect gated structure. One of the important findings is that tunable electronic properties of OTFTs are achieved by controlling C60 composition using a simple and an inexpensive spin-cast technology. The mobility increases with increase in the C60 composition in both n- and p-type OTFTs. Temperature measurements on n-type OTFTs revealed that transport follows a thermally activated hopping transport model with small activation energy.
Show PACS
82.45.Mp Thin layers, films, monolayers, membranes
82.20.Wt Computational modeling; simulation

Minority carrier diffusion length in GaN: Dislocation density and doping concentration dependence

K. Kumakura, T. Makimoto, N. Kobayashi, T. Hashizume, T. Fukui, and H. Hasegawa

Appl. Phys. Lett. 86, 052105 (2005); http://dx.doi.org/10.1063/1.1861116 (3 pages) | Cited 33 times

Online Publication Date: 27 January 2005

Full Text: Read Online (HTML) | Download PDF

Show Abstract
We investigated the minority carrier diffusion length in p- and n-GaN by performing electron-beam-induced current measurements of GaN p–n junction diodes. Minority electron diffusion length in p-GaN strongly depended on the Mg doping concentration for relatively low dislocation density below 108 cm−2. It increased from 220 to 950 nm with decreasing Mg doping concentration from 3×1019 to 4×1018 cm−3. For relatively high dislocation density above 109 cm−2, it was less than 300 nm and independent of the Mg doping concentration. On the other hand, the minority hole diffusion length in n-GaN was shorter than 250 nm and less affected by the dislocation density and Si doping concentration. We discuss the doping-concentration and dislocation-density dependence of minority carrier diffusion length.
Show PACS
66.30.Fq Self-diffusion in metals, semimetals, and alloys
66.30.Xj Thermal diffusivity

Force/displacement detection using quantum transport in InAs/AlGaSb two-dimensional heterostructures

H. Yamaguchi, Y. Hirayama, S. Miyashita, and S. Ishihara

Appl. Phys. Lett. 86, 052106 (2005); http://dx.doi.org/10.1063/1.1861124 (3 pages) | Cited 10 times

Online Publication Date: 28 January 2005

Full Text: Read Online (HTML) | Download PDF

Show Abstract
We fabricated a piezoresistive microelectromechanical cantilever that contains an InAs/Al0.5Ga0.5Sb quantum well and measured the piezoresistance as a function of perpendicular magnetic field at 2.0 K. The magneto-piezoresistance shows the feature of Schvnikov–de Haas oscillation, indicating a strong quantum effect on the piezoresistance. At the magnetic field that gives the largest piezoresistance, displacement and force sensitivities of 10−11 m/math and 10−12 N/math, respectively, were obtained.
Show PACS
85.85.+j Micro- and nano-electromechanical systems (MEMS/NEMS) and devices
73.63.Hs Quantum wells
72.20.Fr Low-field transport and mobility; piezoresistance
07.10.Pz Instruments for strain, force, and torque

Recombination kinetics of Te isoelectronic centers in ZnSTe

X. D. Yang, Z. Y. Xu, Z. Sun, B. Q. Sun, G. H. Li, I. K. Sou, and W. K. Ge

Appl. Phys. Lett. 86, 052107 (2005); http://dx.doi.org/10.1063/1.1861128 (3 pages) | Cited 1 time

Online Publication Date: 28 January 2005

Full Text: Read Online (HTML) | Download PDF

Show Abstract
The recombination kinetics of Te isoelectronic centers in ZnS1−xTex (0.0065 ⩽ x ⩽ 0.85) alloys is studied by time-resolved photoluminescence (TRPL) at low temperature. The measured radiative recombination lifetimes of different Te bound exciton states are quite different, varying from a few nanoseconds to tens of nanosecond. As the bound exciton state evolves from a single Te impurity (Te1) to larger Te clusters (Ten,n = 2,3,4), the recombination lifetime increases. It reaches maximum ( ∼ 40 ns) for the Te4 bound states at x = 0.155. The increase of the exciton lifetime is attributed to the increasing exciton localization effect caused by larger localization potential. In the large Te composition range (x>0.155), the exciton recombination lifetime decreases monotonically with Te composition. It is mainly due to the hybridization between the Te localized states and the host valence band states. The composition dependences of the exciton binding energy and the photoluminescence (PL) line width show the similar tendency that further support the localization picture obtained from the TRPL measurement.
Show PACS
78.66.Hf II-VI semiconductors
73.50.Gr Charge carriers: generation, recombination, lifetime, trapping, mean free paths
71.35.Cc Intrinsic properties of excitons; optical absorption spectra

Highly efficient vertical laser-liftoff GaN-based light-emitting diodes formed by optimization of the cathode structure

D. W. Kim, H. Y. Lee, M. C. Yoo, and G. Y. Yeom

Appl. Phys. Lett. 86, 052108 (2005); http://dx.doi.org/10.1063/1.1861497 (3 pages) | Cited 34 times

Online Publication Date: 28 January 2005

Full Text: Read Online (HTML) | Download PDF

Show Abstract
Vertical GaN-based light-emitting diodes (LEDs) were fabricated using a laser-liftoff process and the effect of the cathode processing conditions on the properties of the LEDs was investigated. Surface roughening by 10% Cl2/90% BCl3 plasma etching improved the light emission intensity at an operating current of 20 mA; however, the forward operating voltage was increased due to the thin and rough n‐GaN layer. The use of an indium tin oxide (ITO) contact on the roughened n-type GaN surface decreased the forward voltage significantly, by decreasing the spreading resistance of the n-type GaN contact without decreasing the emission intensity. Through the combination of the ITO contact and the surface roughness of the n‐GaN layer, a 100% increase in the extraction efficiency was obtained compared to that of a lateral GaN device, with maintaining a similar forward operating voltage.
Show PACS
85.60.Jb Light-emitting devices
81.65.Cf Surface cleaning, etching, patterning
68.35.B- Structure of clean surfaces (and surface reconstruction)
73.40.Cg Contact resistance, contact potential
73.40.Qv Metal-insulator-semiconductor structures (including semiconductor-to-insulator)

Estimation of residual nitrogen concentration in semi-insulating 4H-SiC via low temperature photoluminescence

E. R. Glaser, B. V. Shanabrook, and W. E. Carlos

Appl. Phys. Lett. 86, 052109 (2005); http://dx.doi.org/10.1063/1.1857079 (3 pages) | Cited 4 times

Online Publication Date: 28 January 2005

Full Text: Read Online (HTML) | Download PDF

Show Abstract
The conditions and limitations are presented for using low-temperature photoluminescence to estimate the total residual nitrogen concentration in semi-insulating (SI) 4H-SiC substrates where all N shallow donors are compensated in the dark. The ratio of the nitrogen-bound exciton line (Q0) to the free excitonic-related emission (I77) was tracked as a function of excitation power density for a set of samples with varying residual N concentration ( ∼ 6×1014–5.2×1016 cm−3) as determined by secondary ion mass spectroscopy. A linear relationship was empirically found between the Q0/I77 ratio and [N] for [N]<1×1016 cm−3. However, a sub-linear behavior was observed for samples with higher N levels attributed to incomplete photo-neutralization of the N shallow donors.
Show PACS
61.72.S- Impurities in crystals
71.55.-i Impurity and defect levels
78.55.Hx Other solid inorganic materials
72.80.Jc Other crystalline inorganic semiconductors
72.20.Jv Charge carriers: generation, recombination, lifetime, and trapping
71.35.-y Excitons and related phenomena
82.80.Ms Mass spectrometry (including SIMS, multiphoton ionization and resonance ionization mass spectrometry, MALDI)
Return to All Sections
Close

Google Calendar

ADVERTISEMENT

Go to AIP Home   © AIP Publishing LLC
close