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

12 Dec 2005

Volume 87, Issue 24, Articles (24xxxx)

Issue Cover Spotlight Figure

Appl. Phys. Lett. 87, 243101 (2005); http://dx.doi.org/10.1063/1.2147713 (3 pages)

Y.-S. Choi, K. Hennessy, R. Sharma, E. Haberer, Y. Gao, S. P. DenBaars, S. Nakamura, E. L. Hu, and C. Meier
Enlarge Image | Read More
Return to All Sections
back to top
RSS Feeds

Impact of grain sizes on phonon thermal conductivity of bulk thermoelectric materials

Xiao Jing Zheng, Linli Zhu, You-He Zhou, and Qingjie Zhang

Appl. Phys. Lett. 87, 242101 (2005); http://dx.doi.org/10.1063/1.2137463 (3 pages) | Cited 8 times

Online Publication Date: 5 December 2005

Full Text: Read Online (HTML) | Download PDF

Show Abstract
We report a phonon transport model for a bulk thermoelectric material to investigate the effect of the grain diameter and the grain-boundary thickness on its thermal conductivity. The analysis results display that the bulk thermal conductivity is significantly reduced by decreasing the grain sizes when the grain diameter is less than 500 nm, which provides us one feasible way to enhance the figure of merit ZT of the material, and the thermal conductivity is mainly attributed to the contribution of grains, while the grain-boundary thermal conductivity has to be considered when the grain diameter is less than 100 nm.
Show PACS
66.70.-f Nonelectronic thermal conduction and heat-pulse propagation in solids; thermal waves
72.20.Pa Thermoelectric and thermomagnetic effects
61.72.Mm Grain and twin boundaries

Frequency shift imaging of quantum dots with single-electron resolution

J. Zhu, M. Brink, and P. L. McEuen

Appl. Phys. Lett. 87, 242102 (2005); http://dx.doi.org/10.1063/1.2139623 (3 pages) | Cited 13 times

Online Publication Date: 5 December 2005

Full Text: Read Online (HTML) | Download PDF

Show Abstract
We employ atomic force microscope-based frequency shift microscopy to study the electronic properties of quantum dots formed in carbon nanotubes. The nontransport detection scheme of frequency shift allows us to probe nearly isolated quantum dots in a few electron regime. At 4 K, we observe Coulomb oscillations of quantum dots with single-electron resolution and extract the charging energy of a quantum dot.
Show PACS
73.63.Kv Quantum dots
68.37.Ps Atomic force microscopy (AFM)

Deep-level transient spectroscopy of TiO2/CuInS2 heterojunctions

Marian Nanu, Florence Boulch, Joop Schoonman, and Albert Goossens

Appl. Phys. Lett. 87, 242103 (2005); http://dx.doi.org/10.1063/1.2140611 (3 pages) | Cited 6 times

Online Publication Date: 7 December 2005

Full Text: Read Online (HTML) | Download PDF

Show Abstract
Deep-level transient spectroscopy (DLTS) has been used to measure the concentration and energy position of deep electronic states in CuInS2. Flat TiO2∣CuInS2 heterojunctions as well as TiO2-CuInS2 nanocomposites have been investigated. Subband-gap electronic states in CuInS2 films are mostly due to antisite point defects and vacancies. Substitution of indium with copper, CuInII, leads to an acceptor state 0.15 eV above the valence band, while copper vacancies, VCuI, are acceptor states at 0.1 eV. Furthermore, indium on a copper position, InCu″, yields a donor state at 0.07 eV below the conduction band, while sulphur vacancies are donor states at 0.0 = eV. With DLTS, these states are indeed found. For flat configurations, VCuI are the dominant acceptors with a concentration of 1.83×1017 cm−3. In contrast for nanocomposites CuInII are the dominant acceptors having a concentration of 6.7×1017 cm−3. We conclude that the concentration of antisite defects in nanocomposite CuInS2 is significantly higher than that in flat films of CuInS2.
Show PACS
71.55.Ht Other nonmetals
61.72.J- Point defects and defect clusters
71.20.Nr Semiconductor compounds

Temperature and compositional dependence of the energy band gap of AlGaN alloys

N. Nepal, J. Li, M. L. Nakarmi, J. Y. Lin, and H. X. Jiang

Appl. Phys. Lett. 87, 242104 (2005); http://dx.doi.org/10.1063/1.2142333 (3 pages) | Cited 28 times

Online Publication Date: 7 December 2005

Full Text: Read Online (HTML) | Download PDF

Show Abstract
Deep-ultraviolet photoluminescence spectroscopy has been employed to study the temperature and compositional dependence of the band gap of AlxGa1−xN alloys in the temperature range between 10 and 800 K. Band-edge emission peaks in AlxGa1−xN alloys were fitted by the Varshni equation to obtain Varshni coefficients, which increase nonlinearly with x. The values of Varshni coefficients obtained for GaN and AlN binary compounds in the present study are in good agreement with the previously reported values. Based on the experimental data, the compositional and temperature dependence of the band gap of AlxGa1−xN alloy has been empirically determined for the entire alloy range.
Show PACS
71.20.Nr Semiconductor compounds
78.55.Cr III-V semiconductors

Raman characterization of electronic properties of self-assembled GaN nanorods grown by plasma-assisted molecular-beam epitaxy

D. Wang, C. -C. Tin, J. R. Williams, M. Park, Y. S. Park, C. M. Park, T. W. Kang, and W. -C. Yang

Appl. Phys. Lett. 87, 242105 (2005); http://dx.doi.org/10.1063/1.2146066 (3 pages) | Cited 9 times

Online Publication Date: 8 December 2005

Full Text: Read Online (HTML) | Download PDF

Show Abstract
We have investigated the Raman scattering of the aligned gallium nitride (GaN) nanorods grown by plasma-assisted molecular-beam epitaxy. It was determined by Raman spectroscopy that the GaN nanorods are relatively strain free. The free carrier concentration, as well as electron mobility of the GaN nanorods, was obtained by the line shape analysis of the coupled A1 longitudinal-optical(LO) phonon-plasmon mode. The electron concentration and mobility of electron obtained from line shape analysis are 3.3×1017 cm−3 and 140 cm2 V s, respectively. The local temperature of the nanorod sample was estimated based on the ratio of Stokes to anti-Stokes Raman peak intensity. Since the position of the LO phonon peak was found to be dependent on both the temperature and the LO phonon-plasmon coupling, it is crucial to consider the temperature effect in determining the frequency of the uncoupled LO phonon mode for the line shape analysis. The frequency of the A1(LO) mode of an undoped bulk GaN was used as a reference to determine the frequency of the uncoupled A1(LO) phonon mode of the GaN nanorods.
Show PACS
78.67.Lt Quantum wires
78.30.Fs III-V and II-VI semiconductors
73.63.Nm Quantum wires
72.20.Fr Low-field transport and mobility; piezoresistance
63.20.kk Phonon interactions with other quasiparticles

Defect-driven inhomogeneities in Ni/4H–SiC Schottky barriers

S. Tumakha, D. J. Ewing, L. M. Porter, Q. Wahab, X. Ma, T. S. Sudharshan, and L. J. Brillson

Appl. Phys. Lett. 87, 242106 (2005); http://dx.doi.org/10.1063/1.2141719 (3 pages) | Cited 11 times

Online Publication Date: 8 December 2005

Full Text: Read Online (HTML) | Download PDF

Show Abstract
Nanoscale depth-resolved cathodoluminescence spectroscopy (DRCLS) of Ni diode arrays on 4H-SiC epitaxial wafers reveals a striking correspondence between deep level defects and electrical transport measurements on a diode-by-diode basis. Current-voltage measurements display both ideal and nonideal diode characteristics due to multiple barriers within individual contacts. Near-interface DRCLS demonstrates the presence of three discrete midgap defect levels with 2.2, 2.45, and 2.65 eV emission energies whose concentrations vary on a submicron scale among and within individual diodes, correlating with barrier inhomogeneity. These results also suggest that SiC native defect levels can account for the maximum range of n-type barrier heights.
Show PACS
85.30.Kk Junction diodes
73.30.+y Surface double layers, Schottky barriers, and work functions
78.60.Hk Cathodoluminescence, ionoluminescence

Influences of substitution on electronic structures of oligofluorenes

Chih-I Wu, Guan-Ru Lee, Chan-Tin Lin, Yu-Hung Chen, Yun-Hua Hong, Wei-Guan Liu, Chung-Chih Wu, Ken-Tsung Wong, and Teng-Chih Chao

Appl. Phys. Lett. 87, 242107 (2005); http://dx.doi.org/10.1063/1.2140587 (3 pages) | Cited 3 times

Online Publication Date: 8 December 2005

Full Text: Read Online (HTML) | Download PDF

Show Abstract
The influences of substitutions on the electronic structures of oligofluorenes were systematically investigated. Electronic states of oligofluorenes with various types of C9 substitutions were studied by both ultraviolet photoemission spectroscopy and theoretical calculation. It is found that the substituents could have significant interaction with the backbone and substantially modify the electronic structures of oligofluorenes, depending on the types of substitutions. Consequently, the electronic properties that would affect the operations of electronic devices also considerably depend on the substitutions of the oligofluorenes.
Show PACS
71.20.Rv Polymers and organic compounds
82.30.Hk Chemical exchanges (substitution, atom transfer, abstraction, disproportionation, and group exchange)
79.60.Fr Polymers; organic compounds
79.60.Bm Clean metal, semiconductor, and insulator surfaces
78.40.Me Organic compounds and polymers
78.40.Fy Semiconductors
Return to All Sections
Close

Google Calendar

ADVERTISEMENT

Go to AIP Home   © AIP Publishing LLC
close