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8 Jul 1996

Volume 69, Issue 2, pp. 141-283

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Measurement of linear nanometric distances between smooth plane parallel bodies by scattered total internal reflection

Paul J. Sides and Jenny Lo

Appl. Phys. Lett. 69, 141 (1996); http://dx.doi.org/10.1063/1.116900 (2 pages) | Cited 3 times

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Measurement of linear nanometric distances between perfectly smooth plane parallel surfaces by scattering evanescent waves of internally reflected light is shown to be possible if one of the two surfaces is optically disseminative, that is, it either possesses a heterogeneous index of refraction or it is capable of absorbing and re‐emitting radiation. Good agreement was obtained between the nominal 100 nm fly height of a magnetic recording slider and the 92 nm fly height measured by scattered total internal reflection. This method is simpler and more informative than interferometry or methods that employ the internally reflected beam. © 1996 American Institute of Physics.
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07.60.Hv Refractometers and reflectometers
06.30.Bp Spatial dimensions (e.g., position, lengths, volume, angles, and displacements)

Color‐variable electroluminescence from multilayer polymer films

Maki Hamaguchi and Katsumi Yoshino

Appl. Phys. Lett. 69, 143 (1996); http://dx.doi.org/10.1063/1.116901 (3 pages) | Cited 35 times

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Color‐variable emission has been observed from a multilayer polymer electroluminescent device composed of three polymer layers: perfluoropropylated poly(p‐phenylene) (F‐PPP) sandwiched between two emissive polymers, poly (3‐dodecylthiophene) (PDT) and poly (p‐phenylenevinylene) (PPV). Green and red emissions were observed when a negative bias was applied to the PPV and PDT side electrodes, respectively. F‐PPP was supposed to act as an electron‐blocking layer due to its small electron affinity (2.2 eV) compared with those of PPV (2.7) and PDT (3.5), and to facilitate the confinement of the excitons in the negatively biased polymer layer, where the radiative recombination of the charge carriers takes place. © 1996 American Institute of Physics.
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42.70.Jk Polymers and organics
78.60.Fi Electroluminescence
78.66.Qn Polymers; organic compounds

Single mode Lamb wave excitation in thin plates by Hertzian contacts

F. Levent Degertekin and Butrus T. Khuri‐Yakub

Appl. Phys. Lett. 69, 146 (1996); http://dx.doi.org/10.1063/1.116902 (3 pages) | Cited 7 times

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We present novel techniques to selectively excite the lowest order symmetric (So) and antisymmetric (Ao) Lamb wave modes in thin solid plates. Hertzian contacts are formed between the plates and the end of specially designed quartz rods which guide extensional waves generated by PZT‐5H transducers bonded at their other end. Mode selectivity is achieved by applying shear and/or longitudinal traction at the edge or the surface of the plates according to the results of a two‐dimensional normal mode theory. In aluminum plates, mode selectivity is measured as a function of frequency for different traction forces. With normal forces, Ao mode selectivity of more than 46 dB is obtained for fd<0.4 MHz mm. With antisymmetric shear traction at the edge of the plate, a selectivity exceeding 55 dB is achieved for single mode So operation. © 1996 American Institute of Physics.
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43.38.Ar Transducing principles, materials, and structures: general
43.38.Fx Piezoelectric and ferroelectric transducers
77.65.Dq Acoustoelectric effects and surface acoustic waves (SAW) in piezoelectrics

Kinetic‐energy measurement of a neutral stream extracted from Ar electron cyclotron resonance plasma

Tai Tsuchizawa, Yoshito Jin, and Seitaro Matsuo

Appl. Phys. Lett. 69, 149 (1996); http://dx.doi.org/10.1063/1.116903 (3 pages) | Cited 3 times

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The kinetic energy of a neutral stream within Ar electron cyclotron resonance plasma was evaluated by means of time‐of‐flight mass spectroscopy. The median energy in the distribution of the neutral stream ranged between 10 and 20 eV for pressure from 1.4 to 2.9×10−4 Torr. This energy is almost equal to that of the ions. The energy of the neutral stream could be controlled by adjusting the gas pressure. A higher pressure broadened the energy distribution of the neutral stream. © 1996 American Institute of Physics.
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52.77.Bn Etching and cleaning
52.77.Dq Plasma-based ion implantation and deposition
52.70.Nc Particle measurements
37.20.+j Atomic and molecular beam sources and techniques

Plasma beam deposited amorphous hydrogenated carbon: Improved film quality at higher growth rate

J. W. A. M. Gielen, M. C. M. van de Sanden, and D. C. Schram

Appl. Phys. Lett. 69, 152 (1996); http://dx.doi.org/10.1063/1.116904 (3 pages) | Cited 37 times

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High quality diamondlike a‐C:H has been deposited, at low ion bombardment energies, from an expanding thermal argon/acetylene plasma at high growth rate. It is observed that quality improvement, in terms of hardness, is equivalent to maximization of the refractive index. The highest refractive indices are obtained when the admixed acetylene flow and the argon ion flux emanating from the plasma source are comparable in magnitude, which suggests critical loading. This also indicates that the acetylene has to be dissociated only once. Combination with the observed quality behavior at higher deposition rates suggests that there is one preferred hydrocarbon radical for deposition, probably C2H. © 1996 American Institute of Physics.
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81.15.Gh Chemical vapor deposition (including plasma-enhanced CVD, MOCVD, ALD, etc.)
78.66.Jg Amorphous semiconductors; glasses
61.43.Dq Amorphous semiconductors, metals, and alloys

Morphology of strained epitaxial Fe films on Cu(311)

S. Fölsch, B.‐Ch. Choi, and K. H. Rieder

Appl. Phys. Lett. 69, 155 (1996); http://dx.doi.org/10.1063/1.116905 (3 pages) | Cited 2 times

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Heteroepitaxial growth of Fe on the asymmetrical Cu(311) surface leads to (211)‐oriented strained bcc films with a highly anisotropic morphology. In the initial stage the evolution of pseudomorphic Fe islands is observed: anisotropic lateral stress induces the formation of a regular array of Fe patches with a periodic separation. With proceeding growth, the overlayer transforms to bcc structure by means of dislocations introduced along the direction of dominant stress. The topography of the resulting bcc film corresponds to a regular faceted structure whose periodicity is determined by the arrangement of pseudomorphic islands formed in the initial stage of growth. © 1996 American Institute of Physics.
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68.60.Bs Mechanical and acoustical properties
68.55.-a Thin film structure and morphology
61.05.jh Low-energy electron diffraction (LEED) and reflection high-energy electron diffraction (RHEED)

Hydrogen‐free amorphous carbon films approaching diamond prepared by magnetron sputtering

S. Logothetidis

Appl. Phys. Lett. 69, 158 (1996); http://dx.doi.org/10.1063/1.116906 (3 pages) | Cited 39 times

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Unhydrogenated amorphous carbon films were deposited by rf magnetron sputtering at room temperature. In situ spectroscopic ellipsometry and real time ellipsometry were used to monitor and characterize the films during deposition as well as to define the region of the preparation conditions where carbon films rich in sp3 C–C bonds are deposited. Evidence that the amorphous films exhibit the diamond character as well as their metastability were also provided and discussed by Raman spectroscopy and other techniques. © 1996 American Institute of Physics.
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61.43.Dq Amorphous semiconductors, metals, and alloys
81.15.Cd Deposition by sputtering
78.66.Jg Amorphous semiconductors; glasses

Preparation of epitaxial metallic LaNiO3 films on SrTiO3 by metalorganic decomposition for the oriented growth of PbTiO3

Aidong Li, Chuanzhen Ge, Peng Lü, and Naiben Ming

Appl. Phys. Lett. 69, 161 (1996); http://dx.doi.org/10.1063/1.117358 (3 pages) | Cited 17 times

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Epitaxial metallic LaNiO3 (LNO) films on SrTiO3 (STO) were prepared by metalorganic decomposition. X‐ray θ–2θ scans, x‐ray ϕ scans, and the Rutherford backscattering channeling technique were used to determine the degree of crystallinity of the films. The trend of resistance as a function of annealing temperature of LNO films on STO and Si substrates indicated that LNO films on STO have lower crystalline temperature and higher transition temperature from conductor to insulator than on Si. (001)‐oriented PbTiO3 (PT) films were grown on LNO‐coated STO by the sol‐gel method. Scanning electron microscopy of a cross section of PT/LNO/STO showed sharp boundaries. The ferroelectric capacitor fabricated from these films displayed promising P‐E hysteresis characteristics. © 1996 American Institute of Physics.
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68.55.-a Thin film structure and morphology
85.50.-n Dielectric, ferroelectric, and piezoelectric devices
77.84.Bw Elements, oxides, nitrides, borides, carbides, chalcogenides, etc.
61.05.Np Atom, molecule, and ion scattering (for structure determination only)

Orientational relationship among polyimide alignment layer, liquid crystal monolayer, and bulk pretilt angle

Koichiro Shirota, Michio Yaginuma, Takahiro Sakai, Ken Ishikawa, Hideo Takezoe, and Atsuo Fukuda

Appl. Phys. Lett. 69, 164 (1996); http://dx.doi.org/10.1063/1.117359 (3 pages) | Cited 10 times

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We have determined the orientational distribution function (ODF) of side chains of rubbed polyimide (PI) films and liquid crystal (LC) monolayers on those films (PI & LC) by optical second‐harmonic generation (SHG). To separate the SHG signal of the LC monolayer from that of the (PI & LC) film, the phase difference between the SHG signals from PI and (PI & LC) was measured by an interference method. We found that the ODFs of PI and LC films are quite different. However, serious changes in these ODFs occur at the same rubbing strength, where the pretilt angle also shows a remarkable change. © 1996 American Institute of Physics.
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61.30.Gd Orientational order of liquid crystals; electric and magnetic field effects on order
42.65.Ky Frequency conversion; harmonic generation, including higher-order harmonic generation
78.66.Qn Polymers; organic compounds

Heteroepitaxial growth of KNbO3 single‐crystal films on SrTiO3 by metalorganic chemical vapor deposition

Atsushi Onoe, Ayako Yoshida, and Kiyofumi Chikuma

Appl. Phys. Lett. 69, 167 (1996); http://dx.doi.org/10.1063/1.117360 (3 pages) | Cited 13 times

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Potassium niobate (KNbO3) thin films have been deposited on silicon (Si) and strontium titanate (SrTiO3) substrates by metalorganic chemical vapor deposition. Stoichiometric KNbO3 films were obtained by adjusting the partial pressure of precursors. The crystallinity was examined by x‐ray diffraction and reflection high‐energy electron diffraction. Single‐crystal (010) KNbO3 films with smooth surface were heteroepitaxially grown on (110)SrTiO3 substrate at 850 °C. © 1996 American Institute of Physics.
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77.55.-g Dielectric thin films
81.15.Gh Chemical vapor deposition (including plasma-enhanced CVD, MOCVD, ALD, etc.)
42.70.Nq Other nonlinear optical materials; photorefractive and semiconductor materials
61.05.jh Low-energy electron diffraction (LEED) and reflection high-energy electron diffraction (RHEED)

Electron‐beam induced crystallization transition in self‐developing amorphous AlF3 resists

G. S. Chen, C. B. Boothroyd, and C. J. Humphreys

Appl. Phys. Lett. 69, 170 (1996); http://dx.doi.org/10.1063/1.117361 (3 pages) | Cited 12 times

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Transmission electron microscopy is used to investigate electron‐induced crystallization of thermally evaporated amorphous AlF3(a‐AlF3). It is shown that this material undergoes a very complicated crystallization process with three crystalline substances (Al, AlF3, and Al2O3) formed as the dose increases. The sequence of the crystallization is highly sensitive to the presence of water, which inhibits radiolytic dissociation of a‐AlF3 into Al and fluorine, reduces the dose required for the crystallization of a‐AlF3, and causes the transformation of AlF3 into Al2O3. © 1996 American Institute of Physics.
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61.50.Ks Crystallographic aspects of phase transformations; pressure effects
68.37.Hk Scanning electron microscopy (SEM) (including EBIC)
68.37.Lp Transmission electron microscopy (TEM)
64.70.K- Solid-solid transitions

A critical thickness condition for a strained compliant substrate/epitaxial film system

L. B. Freund and W. D. Nix

Appl. Phys. Lett. 69, 173 (1996); http://dx.doi.org/10.1063/1.117362 (3 pages) | Cited 102 times

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The physical system under study is a single crystal film grown epitaxially on a substrate of comparable thickness which is constrained to remain flat. In general, the layers are strained due to a mismatch in lattice parameter between the film and substrate materials. The free energy change of the system due to formation of strain‐relaxing interface misfit dislocations is estimated, and the discriminating case of zero energy change leads to a critical thickness condition on mismatch strain, film thickness, substrate thickness, and crystallographic slip orientation which is necessary for the spontaneous formation of such dislocations. The condition obtained generalizes the Matthews–Blakeslee (MB) criterion for a thin film on a thick substrate to the case of a complaint substrate/epitaxial film system, and it reduces to the MB criterion when either the film or substrate is relatively thick. © 1996 American Institute of Physics.
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68.55.-a Thin film structure and morphology
68.60.Bs Mechanical and acoustical properties

Effect of adlayer dimer orientation on the optical anisotropy of single domain Si(001)

J. R. Power, T. Farrell, P. Gerber, S. Chandola, P. Weightman, and J. F. McGilp

Appl. Phys. Lett. 69, 176 (1996); http://dx.doi.org/10.1063/1.117363 (3 pages) | Cited 14 times

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The effect of adlayer dimer formation on the optical anisotropy of single domain Si(001) is reported. Reflection anisotropy spectroscopy (RAS) from Ga and Sb adsorbed on the Si(001) surface reveals complex behavior which depends strongly on the atomic species and the RAS signal cannot be simply related to dimer orientation. Dimer formation in the same direction on the surface by Si and Ga is shown to produce RAS signals, below the direct optical gap of Si, of the opposite sign. This contrasts with the simpler behavior observed for Ga and As adsorption on GaAs(001) surfaces. © 1996 American Institute of Physics.
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68.35.Rh Phase transitions and critical phenomena
78.66.Db Elemental semiconductors and insulators

Formation of quasicrystals in bulk glass forming Zr–Cu–Ni–Al alloys

U. Köster, J. Meinhardt, S. Roos, and H. Liebertz

Appl. Phys. Lett. 69, 179 (1996); http://dx.doi.org/10.1063/1.117364 (3 pages) | Cited 219 times

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Zr65Cu17.5Ni10Al7.5 as well as Zr69.5Cu12Ni11Al7.5 belong to the best glass forming alloys known. Glass transition temperatures of melt‐spun ribbons are 372 and 360 °C, respectively. TEM and x‐ray analysis of samples annealed above the glass transition temperature exhibit the formation of quasicrystalline microstructures with small amounts of crystalline phases. The metastable icosahedral phase is primitive with a quasilattice constant a=0.253 nm; its composition as determined by EDX is close to Zr69.5Cu12Ni11Al7.5. In both glasses, growth of the quasicrystals has been observed to be time‐dependent (r∝t1/2), thus indicating a diffusion controlled transformation.
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61.44.Br Quasicrystals
68.37.Hk Scanning electron microscopy (SEM) (including EBIC)
68.37.Lp Transmission electron microscopy (TEM)

Time of flight photoelectron spectroscopy with a laser‐plasma x‐ray source

Hiroyuki Kondo, Toshihisa Tomie, and Hideaki Shimizu

Appl. Phys. Lett. 69, 182 (1996); http://dx.doi.org/10.1063/1.117365 (3 pages) | Cited 15 times

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We are proposing a very compact photoelectron microspectroscopy system with a laser‐plasma x‐ray source, which should give reasonably short spectrum acquisition time. In an experiment using a Q‐switched YAG laser of 0.4 J pulse energy for the production of a laser plasma, it is confirmed that as large number of photoelectrons as expected theoretically is detected, and that the spectral resolution with time of flight method is improved by applying a retardation field. The detected number of Si 2p photoelectrons was 85/pulse in 15 eV bandwidth, and the observed photoelectron spectral resolution was 6 eV close to the bandwidth of the employed Cr/C x‐ray mirror. © 1996 American Institute of Physics.
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07.85.Nc X-ray and γ-ray spectrometers
79.60.-i Photoemission and photoelectron spectra
82.80.Pv Electron spectroscopy (X-ray photoelectron (XPS), Auger electron spectroscopy (AES), etc.)

Defect and transport properties of nanocrystalline CeO2−x

Y.‐M. Chiang, E. B. Lavik, I. Kosacki, H. L. Tuller, and J. Y. Ying

Appl. Phys. Lett. 69, 185 (1996); http://dx.doi.org/10.1063/1.117366 (3 pages) | Cited 117 times

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It is shown that unique defect thermodynamics and transport properties result for oxides of a few nanometers crystallite size. Fully‐dense CeO2−x polycrystals of ∼10 nm grain size were synthesized, and their electrical properties compared with those of samples coarsened from the same material. The nanocrystals showed reduced grain boundary resistance, 104 higher electronic conductivity, and less than one‐half the heat of reduction of its coarse‐grained counterpart. These properties are attributed to a dominant role of interfacial defect formation. © 1996 American Institute of Physics.
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61.46.-w Structure of nanoscale materials
72.20.Fr Low-field transport and mobility; piezoresistance
81.07.-b Nanoscale materials and structures: fabrication and characterization

Combined magnetron sputtering and pulsed laser deposition of carbides and diamond‐like carbon films

A. A. Voevodin, M. A. Capano, A. J. Safriet, M. S. Donley, and J. S. Zabinski

Appl. Phys. Lett. 69, 188 (1996); http://dx.doi.org/10.1063/1.117367 (3 pages) | Cited 54 times

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A hybrid technique is reported, which combines magnetron sputtering and pulsed laser ablation to produce plasma fluxes intersected on a substrate surface to form metal, ceramic and diamond‐like materials. Deposition of crystalline Ti, TixCy, TiCN, and amorphous diamond‐like carbon films at low temperatures by the new technique is discussed. The variation of laser pulse frequency is found to be a simple way to control film chemical composition. The technique can be used to prepare materials with transitional structure, as, for example, between metal carbides and diamond‐like carbon.
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81.15.Fg Pulsed laser ablation deposition
81.15.Cd Deposition by sputtering
68.55.-a Thin film structure and morphology

Layered defective lanthanum titanate thin films prepared by pulsed laser ablation of potassium lanthanum titanate ceramics

S. B. Xiong, W. P. Ding, Z. G. Liu, X. Y. Chen, X. L. Guo, T. Yu, Y. Y. Zhu, and W. S. Hu

Appl. Phys. Lett. 69, 191 (1996); http://dx.doi.org/10.1063/1.117368 (3 pages) | Cited 3 times

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Thin films of Lanthanum titanate have been prepared on SiO2 coated Si and fused silica substrates by excimer ultraviolet laser ablation of potassium lanthanum titanate ceramics (K2La2Ti3O10). X‐ray θ–2θ scans revealed that the films as‐grown at a substrate temperature of 750–850 °C were single phase defective perovskite, and exhibited superstructure line in addition to the lines expected for the foundamenal perovskite structure. The films can be produced by escaping of potassium from K2La2Ti3O10 and the superstructure line observed was considered to arise from the ordered arrangement of the A‐site vacancies. The chemical compositions of the films were determined by x‐ray photoelectron spectroscopy (XPS). Optical waveguiding properties were demonstrated by m‐line measurement using a rutile prism coupling method. The as grown films are colorless and transparent, and have the effective refractive index of 1.917 for TE modes at 632.8 nm. © 1996 American Institute of Physics.
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68.55.-a Thin film structure and morphology
77.84.Ek Niobates and tantalates
77.84.Cg PZT ceramics and other titanates
81.15.Fg Pulsed laser ablation deposition

Synchrotron x‐ray diffraction studies of the structural properties of electrode materials in operating battery cells

T. R. Thurston, N. M. Jisrawi, S. Mukerjee, X. Q. Yang, J. McBreen, M. L. Daroux, and X. K. Xing

Appl. Phys. Lett. 69, 194 (1996); http://dx.doi.org/10.1063/1.117369 (3 pages) | Cited 9 times

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Hard x rays from a synchrotron source were utilized in diffraction experiments which probed the bulk of electrode materials while they were operating in situ in battery cells. Two technologically relevant electrode materials were examined; an AB2‐type anode in a nickel–metal–hydride cell and a LiMn2O4 cathode in a Li‐ion ‘‘rocking chair’’ cell. Structural features such as lattice expansions and contractions, phase transitions, and the formation of multiple phases were easily observed as either hydrogen or lithium was electrochemically intercalated in and out of the electrode materials. The relevance of this technique for future studies of battery electrode materials is discussed. © 1996 American Institute of Physics.
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82.47.-a Applied electrochemistry
07.85.Qe Synchrotron radiation instrumentation
61.05.C- X-ray diffraction and scattering

Thermally induced charged carrier transfer and intersubband transitions in an asymmetrical coupled quantum well structure

Y. Lavon, A. Sa’ar, J. Wang, J.‐P. Leburton, F. H. Julien, and R. Planel

Appl. Phys. Lett. 69, 197 (1996); http://dx.doi.org/10.1063/1.117370 (3 pages) | Cited 6 times

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We have observed thermally induced charged carrier transfer in an asymmetrical coupled quantum wells structure with energy separation between the first two subbands of the order of the LO phonon energy. In this structure, the population of the second subband is not negligible and intersubband transitions from the second to higher excited subbands can be measured. Due to charged carrier transfer, the built‐in dc space charge electric field is changed, giving rise to a blueshift with increasing temperature of the ground to the first excited state intersubband transition. Also, we have found that the measurements of thermally induced intersubband transitions from the second subband provide a direct way to estimate the energy separation between the second subband and the Fermi energy. © 1996 American Institute of Physics.
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73.40.Kp III-V semiconductor-to-semiconductor contacts, p-n junctions, and heterojunctions
78.66.Fd III-V semiconductors

Raman shifts in Si nanocrystals

Jian Zi, H. Büscher, C. Falter, W. Ludwig, Kaiming Zhang, and Xide Xie

Appl. Phys. Lett. 69, 200 (1996); http://dx.doi.org/10.1063/1.117371 (3 pages) | Cited 158 times

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Raman shifts of Si nanocrystals versus size were studied theoretically by a bond polarizability model. Zero‐dimensional spheres and one‐dimensional columns were considered. The relation between the Raman shift and the size for Si spheres and columns was established, from which the size of Si nanocrystals can be obtained for a given Raman shift or vice versa. © 1996 American Institute of Physics.
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61.46.-w Structure of nanoscale materials
63.22.-m Phonons or vibrational states in low-dimensional structures and nanoscale materials
78.30.Am Elemental semiconductors and insulators

Low temperature inorganic chemical vapor deposition of heteroepitaxial GaN

Jeffrey McMurran, M. Todd, J. Kouvetakis, and David J. Smith

Appl. Phys. Lett. 69, 203 (1996); http://dx.doi.org/10.1063/1.117372 (3 pages) | Cited 13 times

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We have developed a highly efficient method of growing thin oriented films of GaN on basal plane sapphire and (100) Si substrates using an exclusively inorganic single‐source precursor free of carbon and hydrogen. Cross sectional transmission electron microscopy of the highly conformal films revealed columnar material growth on Si and heteroepitaxial columnar growth of crystalline GaN on sapphire. Rutherford backscattering spectroscopy (RBS) of layers grown at 700 °C confirmed stoichiometric GaN. Auger and RBS oxygen and carbon resonance profiles indicated that the films were pure and highly homogeneous. With respect to current chemical vapor deposition processes for GaN growth, our approach offers a number of potentially important improvements. These include high growth rates of 5–350 nm/min, low deposition temperature of 650–700 °C, nearly ideal Ga–N stoichiometry, elimination of the highly inefficient use of toxic ammonia, and a carbon–hydrogen free growth environment that could prove to be beneficial to p‐doping processes. © 1996 American Institute of Physics.
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81.15.Gh Chemical vapor deposition (including plasma-enhanced CVD, MOCVD, ALD, etc.)
61.66.Bi Elemental solids
61.66.Dk Alloys
68.37.Hk Scanning electron microscopy (SEM) (including EBIC)
68.37.Lp Transmission electron microscopy (TEM)

On surface plasmons in porous silicon: Measurements of the electron energy loss in etched silicon nanocrystals

R. Massami Sassaki, F. Galembeck, and O. Teschke

Appl. Phys. Lett. 69, 206 (1996); http://dx.doi.org/10.1063/1.117373 (3 pages) | Cited 8 times

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Surface plasmons resulting from the interaction of the electron beam of a transmission electron microscope with porous silicon nanoparticles were measured. The inelastic scattering of fast electrons in H‐covered silicon nanocylinders shows a peak at ∼5.5 eV. A gradual decrease of the first and second order plasma volumetric absorption simultaneous with a constant surface mode absorption amplitude was measured for decreasing silicon‐slab thicknesses. Competitions between bulk and surface effects show, for the volume mode peak at 16.9 eV, a damping factor increase of ∼5 eV. The measured silicon particle diameter was ∼15 Å and a value of the dielectric constant is estimated from the surface plasmon data at 8.5, which is in agreement with recent theoretical work on the modified dielectric constant in quantum confined systems. © 1996 American Institute of Physics.
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73.20.Mf Collective excitations (including excitons, polarons, plasmons and other charge-density excitations)
68.37.Hk Scanning electron microscopy (SEM) (including EBIC)
68.37.Lp Transmission electron microscopy (TEM)
78.55.Mb Porous materials

Trimethylarsenic as an alternative to arsine in the metalorganic vapor phase epitaxy of device quality In0.53Ga0.47As/InP

C. Pautet, P. Abraham, J. Dazord, R. Favre, F. Cauwet, Y. Monteil, J. Bouix, A. Ougazzaden, E. V. K. Rao, and A. Mircea

Appl. Phys. Lett. 69, 209 (1996); http://dx.doi.org/10.1063/1.117374 (3 pages)

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We have investigated the use of trimethylarsenic (TMAs) as an alternative to arsine in the metalorganic vapor phase epitaxy (MOVPE) of device quality InGaAs lattice matched to InP. Films were deposited with arsine or trimethylarsenic over a wide range of growth conditions in a horizontal low pressure (LP)‐MOVPE reactor. In order to minimize carbon incorporation, triethylgallium has been chosen instead of trimethylgallium as the gallium precursor. A minimal growth pressure of 250 mbar and a minimal growth temperature of 550 °C are found to be necessary to ensure specular morphology with TMAs. Electrical and optical properties of InGaAs layers grown using TMAs in the temperature range 600 to 650 °C are comparable to those of layers grown using AsH3. © 1996 American Institute of Physics.
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81.15.Kk Vapor phase epitaxy; growth from vapor phase
85.35.Be Quantum well devices (quantum dots, quantum wires, etc.)
85.60.-q Optoelectronic devices

Optical gain and lasing in self‐assembled InP/GaInP quantum dots

A. Moritz, R. Wirth, A. Hangleiter, A. Kurtenbach, and K. Eberl

Appl. Phys. Lett. 69, 212 (1996); http://dx.doi.org/10.1063/1.117375 (3 pages) | Cited 36 times

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Optical gain measurements have been performed on self‐assembled InP quantum dots embedded in GaInP. The dots are formed during the growth of InP on GaInP by molecular beam epitaxy due to the strong lattice mismatch and are overgrown with GaInP afterwards. The optical gain spectra show two peaks which could be clearly identified by their polarization properties as being due to the quantum dots and the wetting layer, respectively. As expected from the results of the gain measurements, optical pumping of cleaved samples at room temperature leads to lasing of either the quantum dots or the wetting layer, depending on the experimental conditions. © 1996 American Institute of Physics.
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78.66.Fd III-V semiconductors
42.55.Px Semiconductor lasers; laser diodes
85.35.Be Quantum well devices (quantum dots, quantum wires, etc.)
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