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

8 Sep 2008

Volume 93, Issue 10, Articles (10xxxx)

Issue Cover Spotlight Figure

Appl. Phys. Lett. 93, 101905 (2008); http://dx.doi.org/10.1063/1.2977760 (3 pages)

Mei Wang, Yinwei Li, Tian Cui, Yanming Ma, and Guangtian Zou
Enlarge Image | Read More
Return to All Sections
back to top
RSS Feeds

Bias and temperature dependence of the escape processes in quantum dots-in-a-well infrared photodetectors

L. Höglund, P. O. Holtz, H. Pettersson, C. Asplund, Q. Wang, S. Almqvist, S. Smuk, E. Petrini, and J. Y. Andersson

Appl. Phys. Lett. 93, 103501 (2008); http://dx.doi.org/10.1063/1.2977757 (3 pages) | Cited 6 times

Online Publication Date: 8 September 2008

Full Text: Read Online (HTML) | Download PDF

Show Abstract
The performance of quantum dots-in-a-well infrared photodetectors (DWELL IPs) has been studied by means of interband and intersubband photocurrent measurements as well as dark current measurements. Using interband photocurrent measurements, substantial escape of electrons from lower lying states in the DWELL structure at large biases was revealed. Furthermore, a significant variation in the escape probability from energy states in the DWELL structure with applied bias was observed. These facts can explain the strong temperature and bias dependence of both photocurrent and dark currents in DWELL IPs.
Show PACS
07.57.Kp Bolometers; infrared, submillimeter wave, microwave, and radiowave receivers and detectors
85.60.Gz Photodetectors (including infrared and CCD detectors)
85.35.Be Quantum well devices (quantum dots, quantum wires, etc.)

Directional emission control and increased light extraction in GaN photonic crystal light emitting diodes

K. McGroddy, A. David, E. Matioli, M. Iza, S. Nakamura, S. DenBaars, J. S. Speck, C. Weisbuch, and E. L. Hu

Appl. Phys. Lett. 93, 103502 (2008); http://dx.doi.org/10.1063/1.2978068 (3 pages) | Cited 48 times

Online Publication Date: 8 September 2008

Full Text: Read Online (HTML) | Download PDF

Show Abstract
Limitations in extraction efficiency of gallium nitride (GaN) photonic crystal (PhC) light emitting diodes (LEDs) are addressed by implementing an LED design using both two-dimensional PhCs in-plane and index guiding layers (IGLs) in the vertical direction. The effects of PhCs on light extraction and emission directionality from GaN LEDs are studied experimentally. Angular-resolved electroluminescence clearly shows the combined effect of controlling the vertical mode profile with the IGLs and tailoring the emission profile with the periodicity of the PhC lattice. Increases in directional emission as high as 3.5 times are achieved by taking advantage of this directionality and guided mode control.
Show PACS
85.60.Jb Light-emitting devices

A capillary microgripper based on electrowetting

Abhay Vasudev and Jiang Zhe

Appl. Phys. Lett. 93, 103503 (2008); http://dx.doi.org/10.1063/1.2978402 (3 pages) | Cited 7 times

Online Publication Date: 8 September 2008

Full Text: Read Online (HTML) | Download PDF

Show Abstract
An electrowetting based capillary microgripper, which can pick up and release micro-objects, is presented. Electrowetting was utilized to dynamically change the contact angle between the liquid bridge and the gripper surface to control the capillary lifting forces. A coplanar interdigitated gold electrode pair was employed to simplify the microfabrication. The lifting force generated by the microgripper was experimentally characterized. The pickup and release routine was demonstrated for various micro glass beads whose weight ranges from 77 to 136 μN. The design, microfabrication, and testing of the microgripper are presented.
Show PACS
68.08.Bc Wetting
81.16.-c Methods of micro- and nanofabrication and processing

Cathodoluminescence spectroscopy of ambipolar diffusion in (Al,Ga)As barriers and capture of nonequilibrium carriers in GaAs quantum wells

K. Fujiwara, U. Jahn, and H. T. Grahn

Appl. Phys. Lett. 93, 103504 (2008); http://dx.doi.org/10.1063/1.2980021 (3 pages) | Cited 3 times

Online Publication Date: 8 September 2008

Full Text: Read Online (HTML) | Download PDF

Show Abstract
Ambipolar vertical diffusion of carriers generated in an Al0.3Ga0.7As barrier is investigated by cathodoluminescence (CL) spectroscopy in a system containing a sequence of GaAs-based quantum wells (QWs). The intensity distribution of the CL line scan exhibits a single exponential decay for the first QW of the sequence, reflecting a pure diffusion-limited transport. However, the CL line scans of the second, third, and fourth QWs are governed by diffusion only for large separations between the electron beam and the corresponding QW. For smaller distances, the CL intensity distribution is significantly influenced by the carrier capture into the intervening QWs.
Show PACS
78.60.Hk Cathodoluminescence, ionoluminescence
78.66.Fd III-V semiconductors
72.20.Jv Charge carriers: generation, recombination, lifetime, and trapping

Misfit point defects at the epitaxial Lu2O3/(111)Si interface revealed by electron spin resonance

A. Stesmans, P. Somers, V. V. Afanas’ev, W. Tian, L. F. Edge, and D. G. Schlom

Appl. Phys. Lett. 93, 103505 (2008); http://dx.doi.org/10.1063/1.2974793 (3 pages) | Cited 3 times

Online Publication Date: 9 September 2008

Full Text: Read Online (HTML) | Download PDF

Show Abstract
Electron spin resonance study on heteroepitaxial Si/insulator structures obtained through the growth of epi-Lu2O3 films on (111)Si ( ∼ 4.5 % mismatched) by reactive molecular beam epitaxy indicates the presence in the as-grown state of interfacial Pb defects ( ∼ 5×1011 cm−2) with an unpaired sp3 Si dangling bond (DB) along the [111] sample normal, prototypical of the standard thermal (111)Si/SiO2 interface. The defects, with density remaining unchanged to anneal in vacuum up to temperatures of Tan ∼ 420 °C, directly reveal the nonperfect pseudoepitaxial nature of the interface, laid down in electrically detrimental interface traps. These are suggested to be interfacial Si DBs related to Si misfit dislocations. Alarmingly, defect passivation by standard anneal treatments in H2 fall short. For higher Tan, the interface deteriorates to “standard” Si/SiO2 properties, with an attendant appearance of EX centers indicating SiO2 growth. Above Tan ∼ 1000 °C, the interface disintegrates altogether.
Show PACS
68.35.Dv Composition, segregation; defects and impurities
61.72.J- Point defects and defect clusters
61.72.Hh Indirect evidence of dislocations and other defects (resistivity, slip, creep, strains, internal friction, EPR, NMR, etc.)
73.20.At Surface states, band structure, electron density of states
81.65.Rv Passivation

Suppression of spin torque noise in current perpendicular to the plane spin-valves by addition of Dy cap layers

S. Maat, N. Smith, M. J. Carey, and J. R. Childress

Appl. Phys. Lett. 93, 103506 (2008); http://dx.doi.org/10.1063/1.2978958 (3 pages) | Cited 11 times

Online Publication Date: 9 September 2008

Full Text: Read Online (HTML) | Download PDF

Show Abstract
We demonstrate that the addition of Dy capping layers in current perpendicular to the plane giant magnetoresistive spin-valves can increase the critical current density beyond which spin-torque induced instabilities are observed by about a factor of three. While Dy capped samples exhibit nonmagnetic 1/f noise, it is sufficiently small to be unimportant for read head operation at practical data rates.
Show PACS
85.70.Kh Magnetic thin film devices: magnetic heads (magnetoresistive, inductive, etc.); domain-motion devices, etc.
75.70.Cn Magnetic properties of interfaces (multilayers, superlattices, heterostructures)
75.47.De Giant magnetoresistance

Enhancement in output power of blue gallium nitride-based light-emitting diodes with omnidirectional metal reflector under electrode pads

J. K. Sheu, I-Hsiu Hung, W. C. Lai, S. C. Shei, and M. L. Lee

Appl. Phys. Lett. 93, 103507 (2008); http://dx.doi.org/10.1063/1.2980422 (3 pages) | Cited 12 times

Online Publication Date: 9 September 2008

Full Text: Read Online (HTML) | Download PDF

Show Abstract
In this study, we demonstrate a GaN-based light-emitting diode (LED) with nonalloyed metal contacts onto the n+-GaN surface and transparent contact layer (indium tin oxide) to serve as the n-type electrode (cathode) and the p-type electrode pad (anode), respectively. Comparing with the conventional LEDs, which the electrode pads and/or Ohmic contacts form through conventional Cr/Au metal contacts, the nonalloyed metal contacts (Ag/Cr/Au or Al/Cr/Au) used in the present experimental blue LEDs also play the role of reflector to prevent the emitted light from absorption by the opaque electrode pads with low reflectivity (Cr/Au). With an injection current of 20 mA, the enhancement in the light output power has approximately a 14% magnitude compared to the GaN-based LEDs without Ag or Al reflectors under the Cr/Au electrode pads.
Show PACS
85.60.Jb Light-emitting devices

Thermal characterization of light-emitting diodes in the frequency domain

P. Vitta and A. Žukauskas

Appl. Phys. Lett. 93, 103508 (2008); http://dx.doi.org/10.1063/1.2981520 (3 pages) | Cited 6 times

Online Publication Date: 10 September 2008

Full Text: Read Online (HTML) | Download PDF


See Also: Publisher's Note

Show Abstract
We report on a method for the measurement of thermal relaxation time constants within light-emitting diodes (LEDs) in the frequency domain. The method is based on the phase shift of the forward voltage waveform with respect to that of the harmonically modulated forward current due to the sensitivity of the forward voltage to junction temperature. The phase shift was shown to exhibit dips at angular frequencies equal to inverse thermal time constants. Extraction of thermal time constants was demonstrated for common low-power and high-power LEDs. The measured thermal time constants ( ∼ 0.1–100 ms) were linked to heat flows between the LED components.
Show PACS
85.60.Jb Light-emitting devices

Small-signal modeling of the transistor laser including the quantum capture and escape lifetimes

B. Faraji, D. L. Pulfrey, and L. Chrostowski

Appl. Phys. Lett. 93, 103509 (2008); http://dx.doi.org/10.1063/1.2981799 (3 pages) | Cited 6 times

Online Publication Date: 11 September 2008

Full Text: Read Online (HTML) | Download PDF

Show Abstract
The authors report the analytical small-signal modeling of the distribution of minority carriers in the base of a transistor laser and of the high-speed dynamics of the device. The modeling is based on analytically solving the continuity equation and the rate equations, which incorporate the virtual states as a conversion mechanism. Wide-band operation of the transistor laser along with the suppression of the relaxation oscillation frequency peak is demonstrated.
Show PACS
42.55.Px Semiconductor lasers; laser diodes
85.30.Tv Field effect devices

Slow down of the light-induced-degradation in compensated solar-grade multicrystalline silicon

S. Dubois, N. Enjalbert, and J. P. Garandet

Appl. Phys. Lett. 93, 103510 (2008); http://dx.doi.org/10.1063/1.2982098 (3 pages) | Cited 14 times

Online Publication Date: 11 September 2008

Full Text: Read Online (HTML) | Download PDF

Show Abstract
This letter focuses on the kinetics of the light-induced-degradation in multicrystalline silicon, comparing electronic grade and strongly compensated solar-grade materials. In electronic grade material, the results fit well with the models developed for Czochralski grown single-crystals. In contrast, in solar grade material, the light-induced-degradation kinetics are much slower and cannot be described by the existing models. We discuss how the formation of boron-oxygen complexes may be altered by the effects of compensation.
Show PACS
84.60.Jt Photoelectric conversion

Multimodal system for harvesting magnetic and mechanical energy

Shuxiang Dong, Junyi Zhai, J. F. Li, D. Viehland, and S. Priya

Appl. Phys. Lett. 93, 103511 (2008); http://dx.doi.org/10.1063/1.2982099 (3 pages) | Cited 29 times

Online Publication Date: 11 September 2008

Full Text: Read Online (HTML) | Download PDF

Show Abstract
In this letter, we investigate a multimodal system for simultaneous energy harvesting from stray magnetic and mechanical energies by combining magnetoelectric and piezoelectric effects. The system consists of a cantilever beam with tip mass and a magnetoelectric laminate attached in the center of the beam. At 2 Oe magnetic field and mechanical vibration amplitude of 50mg, both at frequency of 20 Hz, the system was found to generate open circuit output voltage of 8 VP.P.. An equivalent circuit model is proposed that predicts a summation effect for both mechanical and magnetic energies.
Show PACS
75.80.+q Magnetomechanical effects, magnetostriction
77.65.-j Piezoelectricity and electromechanical effects
46.40.-f Vibrations and mechanical waves
Return to All Sections
Close

Google Calendar

ADVERTISEMENT

Go to AIP Home   © AIP Publishing LLC
close