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6 Mar 2000

Volume 76, Issue 10, pp. 1219-1345

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Time-resolved photoluminescence studies of AlxGa1−xN alloys

H. S. Kim, R. A. Mair, J. Li, J. Y. Lin, and H. X. Jiang

Appl. Phys. Lett. 76, 1252 (2000); http://dx.doi.org/10.1063/1.126000 (3 pages) | Cited 58 times

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The optical properties of AlxGa1−xN alloys with x varied from 0 to 0.35 have been investigated by picosecond time-resolved photoluminescence (PL) spectroscopy. Our results revealed that while the PL intensity decreases with an increase of Al content, the low-temperature PL decay lifetime increases with Al content. These results can be understood in terms of the effects of tail states in the density of states due to alloy fluctuation in the AlxGa1−xN alloys. The Al-content dependence of the energy-tail-state distribution parameter E0, which is an important parameter for determining optical and electrical properties of the AlGaN alloys, has been obtained experimentally. The PL decay lifetime increases with the localization energy and, consequently, increases with Al content. The implications of our findings to III-nitride optoelectronic device applications are also discussed. © 2000 American Institute of Physics.
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78.55.Cr III-V semiconductors
78.47.-p Spectroscopy of solid state dynamics

Catalytically active nickel {110} surfaces in growth of carbon tubular structures

M. H. Kuang, Z. L. Wang, X. D. Bai, J. D. Guo, and E. G. Wang

Appl. Phys. Lett. 76, 1255 (2000); http://dx.doi.org/10.1063/1.126001 (3 pages) | Cited 30 times

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Recent interest in the growth of aligned carbon nanotube films using transition metal catalysts has led to questions concerning the growth mechanism involved. In our experiment carbon tubules grown using Ni catalysts exhibit a preferred orientation relative to the catalytically active surfaces of Ni. The axial directions of the tubular structure are mainly parallel to the 〈110〉 and 〈042〉 directions of Ni. The faceted shape of the Ni particles determines the intrinsic structure of the tubules. A mechanism involving spiral growth is proposed to explain the nucleation and growth of such tubules. © 2000 American Institute of Physics.
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81.15.Gh Chemical vapor deposition (including plasma-enhanced CVD, MOCVD, ALD, etc.)
82.65.+r Surface and interface chemistry; heterogeneous catalysis at surfaces
61.48.-c Structure of fullerenes and related hollow and planar molecular structures
81.05.ub Fullerenes and related materials
68.55.-a Thin film structure and morphology

Dephasing of coherent phonons by lattice defects in bismuth films

Muneaki Hase, Kunie Ishioka, Masahiro Kitajima, Kiminori Ushida, and Shunichi Hishita

Appl. Phys. Lett. 76, 1258 (2000); http://dx.doi.org/10.1063/1.126002 (3 pages) | Cited 19 times

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We have studied the effect of point defects on coherent optical phonons in ion-implanted bismuth polycrystalline films. Ultrafast dynamics of coherent phonons and photogenerated carriers in the femtosecond time domain have been investigated by means of pump-probe reflectivity measurements. The dephasing rate of the A1g phonon increases linearly with increasing ion dose, which is explained by the additional dephasing process of the coherent phonon originated from scattering of phonons by the defects. Carrier dynamics are also found to be affected by additional scattering process mediated by point defects. © 2000 American Institute of Physics.
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63.20.kp Phonon-defect interactions
68.60.Wm Other nonelectronic physical properties
68.55.Ln Defects and impurities: doping, implantation, distribution, concentration, etc.
73.61.At Metal and metallic alloys
61.72.J- Point defects and defect clusters
72.40.+w Photoconduction and photovoltaic effects
73.50.Pz Photoconduction and photovoltaic effects
78.66.Bz Metals and metallic alloys

Direct wafer bonding and transfer of 10-μm-thick magnetic garnet films onto semiconductor surfaces

T. Izuhara, M. Levy, and R. M. Osgood

Appl. Phys. Lett. 76, 1261 (2000); http://dx.doi.org/10.1063/1.126003 (3 pages) | Cited 8 times

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Bonding between liquid-phase-epitaxy-grown yttrium iron garnet films and various semiconductors is realized by direct wafer bonding. The semiconductor substrates can serve as a platform for integration or as a “handle” platform for the transfer of mesoscopic garnet films. To effect film transfer, a sacrificial layer is formed in the garnet by deep ion implantation prior to bonding. Shear stress at the garnet/semiconductor interface can be controlled by temperature tuning during the bonding process. A debonding temperature threshold of ∼400 °C is found and related to the interfacial thermal stress due to difference in thermal expansion coefficients of the bonded materials. Film separation is realized by the application of thermally induced stress at the sacrificial layer. © 2000 American Institute of Physics.
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75.50.Gg Ferrimagnetics
75.70.Ak Magnetic properties of monolayers and thin films
85.30.-z Semiconductor devices
68.60.Wm Other nonelectronic physical properties

Transplanted Si films on arbitrary substrates using GaN underlayers

Supratik Guha, Arunava Gupta, Nestor A. Bojarczuk, and Joseph Karasinski

Appl. Phys. Lett. 76, 1264 (2000); http://dx.doi.org/10.1063/1.126004 (3 pages) | Cited 1 time

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We demonstrate that Si layers overgrown on GaN/sapphire substrate structures can be transferred onto host substrates by using the technique of laser-induced metallization of GaN at the GaN/sapphire interface via the reaction GaN=Ga+1/2N2. This may allow the grafting of films of Si onto substrates such as glass or plastic for microelectronic applications. We examine the debonding mechanism and propose that it occurs due to pressures of the order of a few thousand atmospheres generated with the release of nitrogen from the GaN metallization reaction. © 2000 American Institute of Physics.
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81.05.Cy Elemental semiconductors
85.40.Ls Metallization, contacts, interconnects; device isolation
68.55.-a Thin film structure and morphology

Effects of nitrogen on the band structure of GaNxP1−x alloys

H. P. Xin, C. W. Tu, Yong Zhang, and A. Mascarenhas

Appl. Phys. Lett. 76, 1267 (2000); http://dx.doi.org/10.1063/1.126005 (3 pages) | Cited 67 times

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We report that the incorporation of N in GaNxP1−x alloys (x ≥ 0.43%) leads to a direct band-gap behavior of GaNP. For N concentration lower than 0.43%, a series of sharp emission lines from the various N pair centers are observed for GaNP bulk layers. With increasing N concentration higher than 0.43%, a strong photoluminescence (PL) emission from GaNP bulk layers is observed at room temperature. While the PL peak redshifts with increasing N concentration to 3.1%, the PL intensity remains as intense. Absorption measurements show a direct band-gap behavior of GaNP alloys. © 2000 American Institute of Physics.
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81.05.Ea III-V semiconductors
71.20.Nr Semiconductor compounds
61.72.uj III-V and II-VI semiconductors
78.55.Cr III-V semiconductors

In situ transmission electron microscopy observation of thin solid aluminum film thermal flow into submicron-sized periodic grooves fabricated on a silicon oxide substrate

Hidehiro Yasuda, Jun-ichi Wada, and Kazuo Furuya

Appl. Phys. Lett. 76, 1270 (2000); http://dx.doi.org/10.1063/1.125899 (3 pages)

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Thin solid aluminum film thermal flow into submicron-sized periodic grooves fabricated on a silicon oxide substrate has been studied in situ by transmission electron microscopy (TEM). Preparation of an aluminum film on the substrate was carried out using an evaporator installed in the specimen chamber of a TEM. The aluminum film was then gradually heated in situ in the microscope. At temperatures around 878 K, the polycrystalline aluminum film on the surface of the substrate started to flow into the grooves, and eventually the grooves were filled with polycrystalline aluminum. At 933 K, the aluminum in the grooves melted. It was confirmed that thin-film thermal flow into the grooves took place in the solid state. It is suggested that a creep deformation of the film driven by surface tension is responsible for this flow. © 2000 American Institute of Physics.
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68.60.Bs Mechanical and acoustical properties
81.40.Lm Deformation, plasticity, and creep
62.20.Hg Creep
85.40.Ls Metallization, contacts, interconnects; device isolation

Interfacial conduction in silica gels containing nanocrystalline copper oxide

D. Das and D. Chakravorty

Appl. Phys. Lett. 76, 1273 (2000); http://dx.doi.org/10.1063/1.126006 (3 pages) | Cited 19 times

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Nanometer-sized copper particles have been grown within a gel derived glass in the system 60 CuO, 40 SiO2 (mole %). By heat treatment at temperatures in the range of 450–850 °C, copper oxide shells of thickness varying from 1.1 to 1.7 nm have been produced. DC resistivity measurements carried out over the temperature range of 30–300 °C show a drastically reduced activation energy as compared to that of a reference sample with the above composition. This is ascribed to the presence of an interfacial amorphous phase generated by the assembly of nanosized copper oxide particles. © 2000 American Institute of Physics.
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72.80.Tm Composite materials
82.70.Gg Gels and sols
73.63.-b Electronic transport in nanoscale materials and structures
61.46.-w Structure of nanoscale materials

Improved brightness, efficiency, and stability of sputter deposited alternating current thin film electroluminescent ZnS:Mn by codoping with potassium chloride

Karen E. Waldrip, J. S. Lewis, Q. Zhai, M. R. Davidson, P. H. Holloway, and S. S. Sun

Appl. Phys. Lett. 76, 1276 (2000); http://dx.doi.org/10.1063/1.126007 (3 pages) | Cited 11 times

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Electroluminescent ZnS:Mn thin films have been codoped with KCl via an ex situ deposition and diffusion process. The brightness, efficiency, and stability of sputter deposited ZnS:Mn alternating current thin film electroluminescent devices have been greatly improved over untreated devices. Potassium chloride doping is shown to have a modest fluxing effect on the grain size of ZnS:Mn films, particularly in the region of the film where nucleation occurs. However, improved electroluminescence is postulated to be strongly influenced by doping control of electric fields and injected charge. © 2000 American Institute of Physics.
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78.60.Fi Electroluminescence
85.60.Pg Display systems
78.66.Hf II-VI semiconductors
68.55.Ln Defects and impurities: doping, implantation, distribution, concentration, etc.
81.15.Cd Deposition by sputtering

Interband optical absorption in free standing layer of Ga0.96In0.04As0.99N0.01

Piotr Perlin, Przemek Wiśniewski, Czesław Skierbiszewski, Tadeusz Suski, Eliana Kamińska, Sudhir G. Subramanya, Eicke R. Weber, Dan E. Mars, and Wladek Walukiewicz

Appl. Phys. Lett. 76, 1279 (2000); http://dx.doi.org/10.1063/1.126008 (3 pages) | Cited 45 times

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We have measured the interband optical absorption of a free-standing sample of Ga0.96In0.04As0.99N0.01 in a wide energy range from 1 to 2.5 eV. We found that the fundamental absorption edge is shifted by 150 meV towards lower energies, and the absorption coefficient measured at higher energies exhibits substantial reduction comparing to that of GaAs. By removing the GaAs substrate, we were able to get an experimental insight into the interband optical transitions and the density of state in this material. The changes can be understood within the band anticrossing model predicting the conduction band splitting. New absorption edges associated with optical transitions from the spin-orbit split off band to the lower conduction subband (1.55 eV) and from the top of the valence band to the upper subband (1.85 eV) are observed. © 2000 American Institute of Physics.
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78.66.Fd III-V semiconductors
78.20.Ci Optical constants (including refractive index, complex dielectric constant, absorption, reflection and transmission coefficients, emissivity)
78.40.Fy Semiconductors
71.20.Nr Semiconductor compounds
78.30.Fs III-V and II-VI semiconductors
71.70.Ej Spin-orbit coupling, Zeeman and Stark splitting, Jahn-Teller effect

Determination of pore-size distribution in low-dielectric thin films

D. W. Gidley, W. E. Frieze, T. L. Dull, J. Sun, A. F. Yee, C. V. Nguyen, and D. Y. Yoon

Appl. Phys. Lett. 76, 1282 (2000); http://dx.doi.org/10.1063/1.126009 (3 pages) | Cited 79 times

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Positronium annihilation lifetime spectroscopy is used to determine the pore-size distribution in low-dielectric thin films of mesoporous methylsilsesquioxane. A physical model of positronium trapping and annihilating in isolated pores is presented. The systematic dependence of the deduced pore-size distribution on pore shape/dimensionality and sample temperature is predicted using a simple quantum mechanical calculation of positronium annihilation in a rectangular pore. A comparison with an electron microscope image is presented. © 2000 American Institute of Physics.
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61.43.Gt Powders, porous materials
68.55.Ln Defects and impurities: doping, implantation, distribution, concentration, etc.
78.70.Bj Positron annihilation
77.84.Jd Polymers; organic compounds
77.55.-g Dielectric thin films
61.72.Qq Microscopic defects (voids, inclusions, etc.)

Temperature dependence of band gap energies of GaAsN alloys

Katsuhiro Uesugi, Ikuo Suemune, Tatsuo Hasegawa, Tomoyuki Akutagawa, and Takayoshi Nakamura

Appl. Phys. Lett. 76, 1285 (2000); http://dx.doi.org/10.1063/1.126010 (3 pages) | Cited 56 times

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The temperature dependence of band gap energies of GaAsN alloys was studied with absorption measurements. As the N concentration in GaAsN increased, the temperature dependence of the band gap energy was clearly reduced in comparison with that of GaAs. The redshift of the absorption edge in GaAsN for the temperature increase from 25 to 297 K was reduced to 60% of that of GaAs for the N concentration larger than ∼1%. The differential temperature coefficient of the energy gap at room temperature was also reduced to 70% of that of GaAs. The main factor for this reduced temperature dependence in GaAsN was attributed to the transition from band-like states to nitrogen-related localized states with detailed studies of the temperature-induced shift of the absorption edge. © 2000 American Institute of Physics.
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71.20.Nr Semiconductor compounds
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