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

1 Oct 2012

Volume 101, Issue 14, Articles (14xxxx)

Issue Cover Spotlight Figure

Appl. Phys. Lett. 101, 141101 (2012); http://dx.doi.org/10.1063/1.4742864 (4 pages)

Po-Hsun Huang, Michael Ian Lapsley, Daniel Ahmed, Yuchao Chen, Lin Wang, and Tony Jun Huang
Enlarge Image | Read More
Return to All Sections
back to top
RSS Feeds

Localized surface plasmon-enhanced ultraviolet electroluminescence from n-ZnO/i-ZnO/p-GaN heterojunction light-emitting diodes via optimizing the thickness of MgO spacer layer

W. Z. Liu, H. Y. Xu, L. X. Zhang, C. Zhang, J. G. Ma, J. N. Wang, and Y. C. Liu

Appl. Phys. Lett. 101, 142101 (2012); http://dx.doi.org/10.1063/1.4757127 (5 pages)

Online Publication Date: 1 October 2012

Full Text: Read Online (HTML) | Download PDF

Show Abstract
Localized surface plasmon (LSP)-enhanced ultraviolet light-emitting diodes were manufactured by introducing Ag nanoparticles and MgO spacer layer into n-ZnO/i-ZnO/p-GaN heterostructures. By optimizing the MgO thickness, which can suppress the undesired charge transfer and nonradiative Förster resonant energy transfer between Ag and ZnO, a 7-fold electroluminescence enhancement was achieved. Time-resolved and temperature-dependent photoluminescence measurements reveal that both spontaneous emission rate and internal quantum efficiency are increased as a result of coupling between ZnO excitons and Ag LSPs, and simple calculations, based on experimental data, also indicate that most of LSP's energy can be converted into the photon energy.
Show PACS
85.60.Jb Light-emitting devices
85.30.Kk Junction diodes

Temperature dependent photon echoes of a GaN thin film

J. R. Schneck, E. Dimakis, J. Woodward, S. Erramilli, T. D. Moustakas, and L. D. Ziegler

Appl. Phys. Lett. 101, 142102 (2012); http://dx.doi.org/10.1063/1.4754091 (4 pages)

Online Publication Date: 1 October 2012

Full Text: Read Online (HTML) | Download PDF

Show Abstract
UV photon echoes from a ∼120 nm GaN thin film exhibit a biexponential decay attributed to the coherence loss of slowly and rapidly decaying excitons corresponding to excitons with different degrees of localization or trapping in this material. Both exciton populations are strongly inhomogeneously broadened. For one exciton type, T2 is ∼300 fs at 10 K and ≤25 fs at 300 K; for the other, T2 is pulse-width limited (≤25 fs) at all temperatures. At low temperatures, coherence decay predominantly results from impurity and defect site interactions. At higher temperatures, strong exciton-LO phonon coupling dominates dephasing.
Show PACS
78.47.jf Photon echoes
71.35.-y Excitons and related phenomena
78.40.Fy Semiconductors
78.66.Fd III-V semiconductors
63.20.kk Phonon interactions with other quasiparticles

Charge sensing in a Si/SiGe quantum dot with a radio frequency superconducting single-electron transistor

Mingyun Yuan, Zhen Yang, D. E. Savage, M. G. Lagally, M. A. Eriksson, and A. J. Rimberg

Appl. Phys. Lett. 101, 142103 (2012); http://dx.doi.org/10.1063/1.4754827 (3 pages)

Online Publication Date: 2 October 2012

Full Text: Read Online (HTML) | Download PDF

Show Abstract
We report the operation of a radio frequency superconducting single-electron transistor (rf-SSET) as a charge sensor for single and double Si/SiGe quantum dots (QDs). Real-time electron tunneling events are observed from the reflected signal of the rf-SSET with a charge sensitivity of 4×10−6 e/math, which demonstrates a fast charge detection time of a few tens of microseconds. Measurements of the reflected power are used to map out the stability diagram of the double quantum dot.
Show PACS
85.35.Gv Single electron devices
85.25.-j Superconducting devices
85.35.Be Quantum well devices (quantum dots, quantum wires, etc.)

Carbon-doped Ge2Sb2Te5 phase change material: A candidate for high-density phase change memory application

Xilin Zhou, Liangcai Wu, Zhitang Song, Feng Rao, Min Zhu, Cheng Peng, Dongning Yao, Sannian Song, Bo Liu, and Songlin Feng

Appl. Phys. Lett. 101, 142104 (2012); http://dx.doi.org/10.1063/1.4757137 (4 pages) | Cited 2 times

Online Publication Date: 2 October 2012

Full Text: Read Online (HTML) | Download PDF

Show Abstract
Carbon-doped Ge2Sb2Te5 material is proposed for high-density phase-change memories. The carbon doping effects on electrical and structural properties of Ge2Sb2Te5 are studied by in situ resistance and x-ray diffraction measurements as well as optical spectroscopy. C atoms are found to significantly enhance the thermal stability of amorphous Ge2Sb2Te5 by increasing the degree of disorder of the amorphous phase. The reversible electrical switching capability of the phase-change memory cells is improved in terms of power consumption with carbon addition. The endurance of ∼2.1 × 104 cycles suggests that C-doped Ge2Sb2Te5 film will be a potential phase-change material for high-density storage application.
Show PACS
84.30.Sk Pulse and digital circuits

Reversible ferromagnetism in rutile TiO2 single crystals induced by nickel impurities

Y. L. Zhao, M. Motapothula, N. L. Yakovlev, Z. Q. Liu, S. Dhar, A. Rusydi, Ariando, M. B. H. Breese, Q. Wang, and T. Venkatesan

Appl. Phys. Lett. 101, 142105 (2012); http://dx.doi.org/10.1063/1.4756799 (4 pages)

Online Publication Date: 3 October 2012

Full Text: Read Online (HTML) | Download PDF

Show Abstract
We report a Ni impurity induced reversible ferromagnetism and surface conduction in rutile TiO2 crystals subjected to specific thermal annealing. For annealing in vacuum at 800 °C, a growing ferromagnetic signal is seen with time while for a similar annealing in air, the magnetism vanishes. The magnetism is concomitant with a surface conductivity which at low temperatures shows tunneling characteristics. Here, we show that Ni magnetic impurity (in TiO2 crystals at <100 ppm) under vacuum annealing segregates to the surface over a 50 nm layer where the Ni concentration exceeds 10%–20% and drops with subsequent air annealing.
Show PACS
75.30.Hx Magnetic impurity interactions
75.50.Dd Nonmetallic ferromagnetic materials
75.70.Rf Surface magnetism
81.40.Gh Other heat and thermomechanical treatments
68.35.Dv Composition, segregation; defects and impurities
73.25.+i Surface conductivity and carrier phenomena

Electronically active defects in the Cu2ZnSn(Se,S)4 alloys as revealed by transient photocapacitance spectroscopy

D. Westley Miller, Charles W. Warren, Oki Gunawan, Tayfun Gokmen, David B. Mitzi, and J. David Cohen

Appl. Phys. Lett. 101, 142106 (2012); http://dx.doi.org/10.1063/1.4754834 (4 pages) | Cited 1 time

Online Publication Date: 3 October 2012

Full Text: Read Online (HTML) | Download PDF

Show Abstract
Transient photocapacitance (TPC) spectra were obtained on a series of Cu2ZnSn(Se,S)4 absorber devices with varying Se:S ratios, providing bandgaps (Eg) between 1 eV and 1.5 eV. Efficiencies varied between 8.3% and 9.3% for devices with Eg ≤ 1.2 eV and were near 6.5% for devices with Eg ≥ 1.4 eV. The TPC spectra revealed a band-tail region with Urbach energies at or below 18 meV for the first group, but in the 25-30 meV range for the higher band-gap samples. A deeper defect band centered near 0.8 eV was also observed in most samples. We identified a correlation between the Urbach energies and the voltage deficit in these devices.
Show PACS
71.55.Ak Metals, semimetals, and alloys
72.40.+w Photoconduction and photovoltaic effects
71.20.Gj Other metals and alloys

Intrinsic threshold mechanism of phase-change memory cells by pulsed current–voltage characterization

W. Chen, Z. Li, J. H. Peng, Y. F. Deng, and X. S. Miao

Appl. Phys. Lett. 101, 142107 (2012); http://dx.doi.org/10.1063/1.4757280 (4 pages)

Online Publication Date: 3 October 2012

Full Text: Read Online (HTML) | Download PDF

Show Abstract
A short pulsed current–voltage (I-V) measurement method is proposed for phase-change random access memory (PCRAM) to investigate the self-heating behavior. The pulse widths and periods are indispensable parameters to describe pulsed I-V characteristics of PCRAM cells. By comparing the difference between direct current I-V curves and pulsed I-V curves, the threshold voltages of pulsed I-V are much higher. It implies the existence of self-heating and energy accumulation. Assume that the heating of the active region causes the change of the electronic barrier and the electronic activity, the physical model dominated by the self-heating in PCRAM cells is proposed.
Show PACS
84.30.Sk Pulse and digital circuits

Spin relaxation of negatively charged excitons in (In,Al)As/AlAs quantum dots with indirect band gap and type-I band alignment

D. Dunker, T. S. Shamirzaev, J. Debus, D. R. Yakovlev, K. S. Zhuravlev, and M. Bayer

Appl. Phys. Lett. 101, 142108 (2012); http://dx.doi.org/10.1063/1.4754619 (4 pages)

Online Publication Date: 4 October 2012

Full Text: Read Online (HTML) | Download PDF

Show Abstract
Spin dynamics of negatively charged excitons is experimentally studied in (In,Al)As/AlAs quantum dots with indirect band gap and type-I band alignment. At low temperatures of 1.8 K, the spin relaxation time is 55 μs in a magnetic field of 3 T. It decreases with increasing magnetic field as B−5, which evidences that the spin relaxation of the negatively charged excitons is provided by an one-acoustic-phonon process.
Show PACS
72.20.Jv Charge carriers: generation, recombination, lifetime, and trapping
73.61.Ey III-V semiconductors
63.22.-m Phonons or vibrational states in low-dimensional structures and nanoscale materials
71.35.-y Excitons and related phenomena

Compositionally graded relaxed AlGaN buffers on semipolar GaN for mid-ultraviolet emission

Erin C. Young, Feng Wu, Alexey E. Romanov, Daniel A. Haeger, Shuji Nakamura, Steven P. Denbaars, Daniel A. Cohen, and James S. Speck

Appl. Phys. Lett. 101, 142109 (2012); http://dx.doi.org/10.1063/1.4757423 (5 pages)

Online Publication Date: 4 October 2012

Full Text: Read Online (HTML) | Download PDF

Show Abstract
In this Letter, we report on the growth and properties of relaxed, compositionally graded AlxGa1 − xN buffer layers on freestanding semipolar (20math1) GaN substrates. Continuous and step compositional grades with Al concentrations up to x = 0.61 have been achieved, with emission wavelengths in the mid-ultraviolet region as low as 265 nm. Coherency stresses were relaxed progressively throughout the grades by misfit dislocation generation via primary (basal) slip and secondary (non-basal) slip systems. Threading dislocation densities in the final layers of the grades were less than 106/cm2 as confirmed by plan-view transmission electron microscopy and cathodoluminescence studies.
Show PACS
81.15.Hi Molecular, atomic, ion, and chemical beam epitaxy
68.55.ag Semiconductors
61.72.Ff Direct observation of dislocations and other defects (etch pits, decoration, electron microscopy, x-ray topography, etc.)
78.60.Hk Cathodoluminescence, ionoluminescence
78.66.Fd III-V semiconductors
81.05.Ea III-V semiconductors

A simple method for the determination of doping type in nanomaterials based on electrical response to humidity

Jin-Woo Han, Beomseok Kim, Nobuhiko P. Kobayashi, Jing Li, and M. Meyyappan

Appl. Phys. Lett. 101, 142110 (2012); http://dx.doi.org/10.1063/1.4757609 (3 pages)

Online Publication Date: 4 October 2012

Full Text: Read Online (HTML) | Download PDF

Show Abstract
A simple method to determine the doping type of inorganic nanomaterials is presented. The surface reaction with moisture results in distinctive electrical responses depending on the doping type of the material. The moisture acts as an electron donor, releasing electrons to the semiconductor materials. Thus, the resistance of p-type materials increases due to the withdrawal of holes, while that of n-type decreases due to electron donation. Compared to spectroscopy and Hall measurement techniques, the present method is a simple and fast approach for determining the doping types, enabling fast feedback in material research as well as in device prototyping.
Show PACS
81.07.-b Nanoscale materials and structures: fabrication and characterization
61.72.U- Doping and impurity implantation
73.63.-b Electronic transport in nanoscale materials and structures

Monolithic integration of high electron mobility InAs-based heterostructure on exact (001) Silicon using a GaSb/GaP accommodation layer

L. Desplanque, S. El Kazzi, C. Coinon, S. Ziegler, B. Kunert, A. Beyer, K. Volz, W. Stolz, Y. Wang, P. Ruterana, and X. Wallart

Appl. Phys. Lett. 101, 142111 (2012); http://dx.doi.org/10.1063/1.4758292 (4 pages)

Online Publication Date: 5 October 2012

Full Text: Read Online (HTML) | Download PDF

Show Abstract
We report on the epitaxial growth of high electron mobility AlSb/InAs heterostructure on exactly oriented (001) Si substrate, using a GaP interfacial layer. The growth conditions are first optimized on GaP substrates to achieve the highest electron mobility. The influence of the Sb flux during the early stage of the GaSb buffer layer is particularly emphasized. Using these optimized growth conditions, the AlSb/InAs heterostructure is grown on a GaP/Si template obtained by metal-organic vapor phase epitaxy. An electron mobility as high as 27 800 cm2 V−1 s−1 and 111 000 cm2 V−1 s−1, respectively, at 300 and 77 K is demonstrated.
Show PACS
73.40.Kp III-V semiconductor-to-semiconductor contacts, p-n junctions, and heterojunctions
81.15.Kk Vapor phase epitaxy; growth from vapor phase
72.20.Fr Low-field transport and mobility; piezoresistance

The effect of hydrogen on the surface segregation of phosphorus in epitaxially grown relaxed Si0.7Ge0.3 films by rapid thermal chemical vapor deposition

Jiun-Yun Li, Chiao-Ti Huang, and James C. Sturm

Appl. Phys. Lett. 101, 142112 (2012); http://dx.doi.org/10.1063/1.4757123 (4 pages)

Online Publication Date: 5 October 2012

Full Text: Read Online (HTML) | Download PDF

Show Abstract
The surface segregation of phosphorus in relaxed Si0.7Ge0.3 epitaxial films grown on Si (100) substrates by rapid thermal chemical vapor deposition was investigated in this letter. The effect of the growth temperature on phosphorus segregation was studied experimentally and examined using a two-state model. As the growth temperature is reduced, phosphorus segregation is greatly suppressed, and we report an extremely sharp phosphorus turn-off slope of 6 nm/dec at 500 °C. The sharper slopes at low temperatures are explained by a modified two-state model which includes the effect of increased surface coverage of hydrogen at low temperatures.
Show PACS
68.35.Dv Composition, segregation; defects and impurities
81.15.Gh Chemical vapor deposition (including plasma-enhanced CVD, MOCVD, ALD, etc.)
68.55.ag Semiconductors
Return to All Sections
Close

Google Calendar

ADVERTISEMENT

Go to AIP Home   © AIP Publishing LLC
close