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3 Mar 1997

Volume 70, Issue 9, pp. 1065-1181

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Energy enhancement of harmonic photons with a half-period-delayed pulse

Suxing Hu and Zhizhan Xu

Appl. Phys. Lett. 70, 1065 (1997); http://dx.doi.org/10.1063/1.118484 (3 pages) | Cited 7 times

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We present a method to enhance the energy of the harmonic photon, namely using an additional half-period-delayed pulse. Because of the interference effect of two pulses, the interaction time between the external field and the atomic system is shortened. Thus, the atomic system can sustain a more intense laser pulse. It means that the actual intensity which contributes to harmonic emission will be increased. Therefore, the harmonic is extended to higher order. Our numerical simulations indicate the substantial energy increment of harmonic photons. © 1997 American Institute of Physics.
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42.65.Ky Frequency conversion; harmonic generation, including higher-order harmonic generation
42.55.Ah General laser theory

Photosensitivity and grating writing in hydrogen loaded germanosilicate core optical fibers at 325 and 351 nm

Robert M. Atkins and Rolando P. Espindola

Appl. Phys. Lett. 70, 1068 (1997); http://dx.doi.org/10.1063/1.118486 (2 pages) | Cited 11 times

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A refractive index grating has been side written in the core of a hydrogen loaded germanosilicate optical fiber using a phase mask and 351 nm light from an Ar ion laser, the longest wavelength yet reported, to the best of our knowledge, for a grating of this type. The grating strength was ∼1.25 dB, indicating an index change of ∼ 2×10−4. The fiber was sensitized by low temperature hydrogen loading followed by a brief exposure to a CO2 laser, resulting in the formation of high levels of germanium–oxygen deficiency centers. Fluorescence changes and UV transmission changes in hydrogen loaded germanosilicate glasses exposed to 325 nm and combined 351/364 nm radiation are also reported. © 1997 American Institute of Physics.
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42.81.Wg Other fiber-optical devices
42.81.Cn Fiber testing and measurement of fiber parameters
42.81.Dp Propagation, scattering, and losses; solitons
78.20.Ci Optical constants (including refractive index, complex dielectric constant, absorption, reflection and transmission coefficients, emissivity)
42.79.Dj Gratings
78.55.Hx Other solid inorganic materials

Nonaxial sites for Er in LiNbO3

L. Rebouta, M. F. da Silva, J. C. Soares, D. Serrano, E. Diéguez, F. Agulló-López, and J. Tornero

Appl. Phys. Lett. 70, 1070 (1997); http://dx.doi.org/10.1063/1.118487 (3 pages) | Cited 10 times

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Off-axis sites for Er have been identified and investigated in congruent LiNbO3 by ion-beam/channeling techniques. They do not constitute a different crystalline phase and appear to be associated to clusters or amorphous precipitates. The axial Er ions lie at the Li octahedron but shifted about 0.2 Å from the regular lattice site. Their concentration increases with total Er doping up to saturation level of about 2%. © 1997 American Institute of Physics.
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61.72.S- Impurities in crystals
61.80.Jh Ion radiation effects
61.85.+p Channeling phenomena (blocking, energy loss, etc.)
64.75.-g Phase equilibria
81.30.Mh Solid-phase precipitation

Fermi level pinning and differential efficiency in GaInP quantum well laser diodes

P. M. Smowton and P. Blood

Appl. Phys. Lett. 70, 1073 (1997); http://dx.doi.org/10.1063/1.118488 (3 pages) | Cited 6 times

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Analysis of spontaneous emission spectra of GaInP quantum well laser diodes above and below threshold show that the quasi-Fermi level separation pins within the quantum wells but not throughout the whole device structure. By reproducing the temperature and cavity length dependence of the external differential efficiency using these measurements it is shown that a value of internal differential efficiency which is nonunity is due to current spreading and incomplete carrier injection and that the temperature dependence is due to the temperature dependence of the efficiency with which carriers are injected into the quantum well.© 1997 American Institute of Physics.
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42.55.Px Semiconductor lasers; laser diodes
73.21.-b Electron states and collective excitations in multilayers, quantum wells, mesoscopic, and nanoscale systems
42.60.Da Resonators, cavities, amplifiers, arrays, and rings

Optical gain in optically pumped cubic GaN at room temperature

R. Klann, O. Brandt, H. Yang, H. T. Grahn, and K. H. Ploog

Appl. Phys. Lett. 70, 1076 (1997); http://dx.doi.org/10.1063/1.118489 (2 pages) | Cited 23 times

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We investigate the transient surface emission and the optical gain of cubic GaN on GaAs(001) upon pulsed optical pumping at room temperature. The initial decay time of the transient surface emission drastically decreases with increasing excitation density, reaching a value as short as 20 ps at a fluence of 50 μJ cm−2. This rapid decay suggests the presence of laterally amplified spontaneous emission. In fact, gain-stripe measurements of the edge emission reveal an optical gain exceeding 100 cm−1 at a fluence of 20 μJ cm−2. © 1997 American Institute of Physics.
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78.45.+h Stimulated emission
78.55.Cr III-V semiconductors
42.50.-p Quantum optics

Deposition of silicon dioxide films on amorphous carbon films by plasma enhanced chemical vapor deposition for low dielectric constant interlayer dielectrics

Kazuhiko Endo, Toru Tatsumi, and Yoshihisa Matsubara

Appl. Phys. Lett. 70, 1078 (1997); http://dx.doi.org/10.1063/1.118490 (2 pages) | Cited 5 times

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Deposition of silicon dioxide films on fluorinated amorphous carbon films (a-C:F) for low dielectric constant interlayer dielectrics was investigated. Both SiO2 and a-C:F films were deposited by helicon wave plasma enhanced chemical vapor deposition with C4F8 for a-C:F and SiH4+O2 mixtures for SiO2. The SiO2 films on the a-C:F films peeled off soon after deposition. However, the peeling was suppressed by inserting a thin a-C:H buffer layer grown from CH4 between them. The adhesion between the films was increased by making the stoichiometry of SiO2 Si-rich. It was found that the Si–C bonds formed at the interface increased the adhesion. © 1997 American Institute of Physics.
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81.15.Gh Chemical vapor deposition (including plasma-enhanced CVD, MOCVD, ALD, etc.)
85.40.Sz Deposition technology
77.22.Ch Permittivity (dielectric function)
61.66.Bi Elemental solids
61.66.Dk Alloys
68.35.Gy Mechanical properties; surface strains

Properties of SrBi2Ta2O9 ferroelectric thin films prepared by a modified metalorganic solution deposition technique

P. C. Joshi, S. O. Ryu, X. Zhang, and S. B. Desu

Appl. Phys. Lett. 70, 1080 (1997); http://dx.doi.org/10.1063/1.118485 (3 pages) | Cited 42 times

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Polycrystalline SrBi2Ta2O9 thin films having a layered-perovskite structure were fabricated by a modified metalorganic solution deposition technique using room temperature processed alkoxidecarboxylate precursor solution. It was possible to obtain a complete perovskite phase at an annealing temperature of 650 °C and no pyrochlore phase was observed even up to 600 °C. In addition, the SrBi2Ta2O9 thin films annealed at 750 °C exhibited better structural, dielectric, and ferroelectric properties than those reported by previous techniques. The effects of postdeposition annealing on the structural, dielectric, and ferroelectric properties were analyzed. The electrical measurements were conducted on Pt/SrBi2Ta2O9/Pt capacitors. The typical measured small signal dielectric constant and dissipation factor at 100 kHz were 330 and 0.023 and the remanent polarization and the coercive field were 8.6 μC/cm2 and 23 kV/cm, respectively, for 0.25-μm-thick films annealed at 750 °C. The leakage current density was lower than 10−8 A/cm2 at an applied electric field of 150 kV/cm. The films showed good switching endurance under bipolar stressing at least up to 1010 switching cycles. © 1997 American Institute of Physics.
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77.84.Ek Niobates and tantalates
77.84.Cg PZT ceramics and other titanates
77.80.Fm Switching phenomena
77.22.Ch Permittivity (dielectric function)
77.22.Ej Polarization and depolarization
85.50.-n Dielectric, ferroelectric, and piezoelectric devices
84.32.Tt Capacitors

Dynamic alignment of magnetic materials

Y. D. Zhang and J. I. Budnick

Appl. Phys. Lett. 70, 1083 (1997); http://dx.doi.org/10.1063/1.118491 (3 pages) | Cited 7 times

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The inherent relation between the crystal and magnetic structures for magnetically ordered materials makes it possible to align magnetic particles using magnetic means. The traditionally used static alignment method can only align the particles in one dimension. This report describes dynamic alignment methods which cause the magnetic particles to orient in various patterns according to one’s needs. In particular, particles can be aligned in all three spatial directions thus forming a single-crystallike aggregate of polycrystalline materials. © 1997 American Institute of Physics.
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75.40.Gb Dynamic properties (dynamic susceptibility, spin waves, spin diffusion, dynamic scaling, etc.)
75.25.-j Spin arrangements in magnetically ordered materials (including neutron and spin-polarized electron studies, synchrotron-source x-ray scattering, etc.)
75.30.Gw Magnetic anisotropy

Thin film growth of semiconducting Mg2Si by codeposition

André Vantomme, John E. Mahan, Guido Langouche, James P. Becker, Margriet Van Bael, Kristiaan Temst, and Chris Van Haesendonck

Appl. Phys. Lett. 70, 1086 (1997); http://dx.doi.org/10.1063/1.118492 (3 pages) | Cited 19 times

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Ultrahigh vacuum evaporation of magnesium onto a hot silicon substrate (⩾200 °C), with the intention of forming a Mg2Si thin film by reaction, does not result in any accumulation of magnesium or its silicide. On the other hand, codeposition of magnesium with silicon at 200 °C, using a magnesium-rich flux ratio, gives a stoichiometric Mg2Si film which can be grown several hundreds of nm thick. The number of magnesium atoms which condense is equal to twice the number of silicon atoms which were deposited; all the silicon condenses while the excess magnesium in the flux desorbs. The Mg2Si layers thus obtained are polycrystalline with a (111) texture. From the surface roughness analysis, a self-affine growth mode with a roughness exponent equal to 1 is deduced. © 1997 American Institute of Physics.
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81.05.Hd Other semiconductors
81.15.-z Methods of deposition of films and coatings; film growth and epitaxy
68.55.Nq Composition and phase identification
68.35.B- Structure of clean surfaces (and surface reconstruction)

Phase separation in InGaN thick films and formation of InGaN/GaN double heterostructures in the entire alloy composition

R. Singh, D. Doppalapudi, T. D. Moustakas, and L. T. Romano

Appl. Phys. Lett. 70, 1089 (1997); http://dx.doi.org/10.1063/1.118493 (3 pages) | Cited 186 times

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We report the growth of InGaN thick films and InGaN/GaN double heterostructures by molecular beam epitaxy at the substrate temperatures 700–800 °C, which is optimal for the growth of GaN. X-ray diffraction and optical absorption studies show phase separation of InN for InxGal−xN thick films with x>0.3. On the other hand, InxGal−xN/GaN double heterostructures show no evidence of phase separation within the detection capabilities of our methods. These observations were accounted for using Stringfellow’s model on phase separation, which gives a critical temperature for miscibility of the GaN–InN system equal to 2457 K.© 1997 American Institute of Physics.
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68.60.-p Physical properties of thin films, nonelectronic
81.15.Hi Molecular, atomic, ion, and chemical beam epitaxy
81.05.Ea III-V semiconductors
78.66.Fd III-V semiconductors
78.40.Fy Semiconductors
72.80.Ey III-V and II-VI semiconductors
73.40.Kp III-V semiconductor-to-semiconductor contacts, p-n junctions, and heterojunctions
81.30.Dz Phase diagrams of other materials
78.20.Ci Optical constants (including refractive index, complex dielectric constant, absorption, reflection and transmission coefficients, emissivity)

Atomic layer controlled growth of SiO2 films using binary reaction sequence chemistry

J. W. Klaus, A. W. Ott, J. M. Johnson, and S. M. George

Appl. Phys. Lett. 70, 1092 (1997); http://dx.doi.org/10.1063/1.118494 (3 pages) | Cited 30 times

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SiO2 thin films were deposited with atomic layer control using binary reaction sequence chemistry. The SiO2 growth was accomplished by separating the binary reaction SiCl4+2H2O→SiO2+4HCl into two half-reactions. Successive application of the half-reactions in an ABAB… sequence produced SiO2 deposition at temperatures between 600 and 800 K and reactant pressures of 1–10 Torr. The SiO2 growth was monitored using ellipsometry versus substrate temperature and reactant exposure time. The maximum SiO2 deposition per AB cycle was 1.1 Å/AB cycle at 600 K. The surface topography measured using atomic force microscopy was extremely flat with a roughness nearly identical to the initial substrate. © 1997 American Institute of Physics.
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81.15.Gh Chemical vapor deposition (including plasma-enhanced CVD, MOCVD, ALD, etc.)
68.35.B- Structure of clean surfaces (and surface reconstruction)
82.65.+r Surface and interface chemistry; heterogeneous catalysis at surfaces
78.66.Nk Insulators

Thermal decomposition of ultrathin oxide layers on Si(111) surfaces mediated by surface Si transport

Heiji Watanabe, Ken Fujita, and Masakazu Ichikawa

Appl. Phys. Lett. 70, 1095 (1997); http://dx.doi.org/10.1063/1.118495 (3 pages) | Cited 39 times

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Thermal decomposition of ultrathin oxide layers (less than 1 nm thick) on Si(111) surfaces was studied by using scanning reflection electron microscopy and scanning tunneling microscopy. Void formation, where the diameter and density of the voids depend on the oxide film thickness, occurred on terraces randomly and independently of the buried steps at SiO2/Si(111) interfaces. Decomposition of the oxide layers caused by the void growth produced atomic-height holes on exposed Si surfaces. The surface roughness produced by the holes after thermal decomposition increased with the thickness of the oxide layers. The surface mass transport of Si adatoms to form volatile SiO products explains these experimental results. © 1997 American Institute of Physics.
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81.65.Mq Oxidation
81.05.Cy Elemental semiconductors
82.30.Lp Decomposition reactions (pyrolysis, dissociation, and fragmentation)
68.35.B- Structure of clean surfaces (and surface reconstruction)
68.35.Ct Interface structure and roughness
73.20.Mf Collective excitations (including excitons, polarons, plasmons and other charge-density excitations)

Thermal and ion irradiation stability of direct current sputtered TiN/B–C–N multilayers

S. Fayeulle, M. Nastasi, Y. C. Lu, H. Kung, and J. R. Tesmer

Appl. Phys. Lett. 70, 1098 (1997); http://dx.doi.org/10.1063/1.118496 (3 pages) | Cited 3 times

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The response of TiN/B–C–N multilayers to vacuum annealing at 900 °C and to 300 keV argon irradiation is studied. Changes in composition, stress field, bilayer repeat length, and layered structure are reported. The modifications observed during thermal annealing are mainly related to the departure of nitrogen because of the initial high state of compressive stress. During irradiation, the viscous flow of atoms perpendicular to the stress field causes an increase of the bilayer repeat length and interdiffusion between each layer. This mechanism leads to relaxation of stress and to the disappearance of the layered structure for higher dose. © 1997 American Institute of Physics.
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68.65.-k Low-dimensional, mesoscopic, nanoscale and other related systems: structure and nonelectronic properties
61.80.Jh Ion radiation effects
81.40.Gh Other heat and thermomechanical treatments
68.35.Gy Mechanical properties; surface strains
66.30.Ny Chemical interdiffusion; diffusion barriers

Effects of interface charges on imprint of epitaxial Bi4Ti3O12 thin films

B. H. Park, T. W. Noh, J. Lee, C. Y. Kim, and W. Jo

Appl. Phys. Lett. 70, 1101 (1997); http://dx.doi.org/10.1063/1.118497 (3 pages) | Cited 17 times

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Using La0.5Sr0.5CoO3 (LSCO) or Pt film as a bottom electrode layer, epitaxial Bi4Ti3O12 (BTO) thin films were grown on MgO(001) substrates by pulsed laser deposition. A symmetric Pt/BTO/Pt capacitor structure shows a surprisingly large asymmetric polarization switching behavior, but a Pt/BTO/LSCO structure has a nearly symmetric P–V hysteresis. The strong asymmetric behavior in the Pt/BTO/Pt was attributed to positive charges resulting from interdiffusion at the bottom BTO/Pt interface. P–V hysteresis studies using numerous top electrode materials and Auger electron spectroscopy depth profile measurement also support formation of interfacial charges. Imprint pulse test shows that such an imprint failure cannot be recovered by applying a dc bias field.© 1997 American Institute of Physics.
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77.55.-g Dielectric thin films
77.84.Bw Elements, oxides, nitrides, borides, carbides, chalcogenides, etc.
77.80.Fm Switching phenomena
81.15.Fg Pulsed laser ablation deposition
84.32.Tt Capacitors
85.50.-n Dielectric, ferroelectric, and piezoelectric devices
77.22.Ej Polarization and depolarization
77.80.Dj Domain structure; hysteresis
66.30.Ny Chemical interdiffusion; diffusion barriers
68.35.Fx Diffusion; interface formation
68.35.Ct Interface structure and roughness
79.20.Fv Electron impact: Auger emission

Nanostructure fabrication by selective growth of molecular crystals on layered material substrates

Keiji Ueno, Kentaro Sasaki, Natsuko Takeda, Koichiro Saiki, and Atsushi Koma

Appl. Phys. Lett. 70, 1104 (1997); http://dx.doi.org/10.1063/1.118498 (3 pages) | Cited 7 times

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Nanostructures consisting of C60 molecules were fabricated on a GaSe/MoS2 heterostructure. A submonolayer film of a lamellar compound semiconductor GaSe was grown on a MoS2 substrate to form nanoscale holes or grooves surrounded by monolayer steps. Atomic force microscope (AFM) observation indicates that C60 molecules grow only in the bare MoS2 nanoregions at a substrate temperature of 180 °C. C60 molecules fill up those holes and grooves, and nanoscale C60 domains with polygonal shapes can be formed. This selective growth method can be combined with nanoscale patterning made by a scanning tunneling microscope or AFM to produce nanostructures of molecular crystals with designed shapes.© 1997 American Institute of Physics.
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81.07.-b Nanoscale materials and structures: fabrication and characterization
61.46.-w Structure of nanoscale materials
61.48.-c Structure of fullerenes and related hollow and planar molecular structures
81.05.ub Fullerenes and related materials
68.37.Ef Scanning tunneling microscopy (including chemistry induced with STM)
68.37.Ps Atomic force microscopy (AFM)
68.37.Rt Magnetic force microscopy (MFM)
68.37.Uv Near-field scanning microscopy and spectroscopy

Reflection anisotropy spectroscopy study of the near surface electric field in low-temperature grown GaAs (001)

Todd Holden, Fred H. Pollak, J. L. Freeouf, D. McInturff, J. L. Gray, M. Lundstrom, and J. M. Woodall

Appl. Phys. Lett. 70, 1107 (1997); http://dx.doi.org/10.1063/1.118499 (3 pages) | Cited 12 times

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We have evaluated an “effective depletion width” of ⩽45 Å and the sign (n-type/upward band bending) of the near surface electric field in low-temperature grown GaAs (001) using the optical method of reflection anisotropy spectroscopy in the vicinity of the spin-orbit split E1, E1+Δ1 optical features. Our results provide evidence that surface Fermi level pinning occurs for air exposed (001) surfaces of undoped low temperature grown GaAs. © 1997 American Institute of Physics.
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73.30.+y Surface double layers, Schottky barriers, and work functions
78.20.Jq Electro-optical effects
73.20.At Surface states, band structure, electron density of states
71.70.Ej Spin-orbit coupling, Zeeman and Stark splitting, Jahn-Teller effect

Nanocomposite resist system

Tetsuyoshi Ishii, Hiroshi Nozawa, and Toshiaki Tamamura

Appl. Phys. Lett. 70, 1110 (1997); http://dx.doi.org/10.1063/1.118500 (3 pages) | Cited 17 times

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We propose a nanocomposite resist system that incorporates sub-nm carbon particles into a resist film to enable an ultrathin film resist process for nanometer pattern fabrication. Fullerene (C60) is found to be an excellent material for incorporation in view of its etching resistance, dissolution inhibiting effect, molecular size, and composite preparation. A nanocomposite system of C60 and an electron-beam positive resist, ZEP520, show enhancements in both pattern contrast and etching resistance and provide 50 nm patterns in a 50-nm-thick film with a sensitivity of ∼ 50 μC/cm2. Furthermore, a C60-incorporated chemically amplified resist, SAL601, shows strong environmental stabilization in postexposure delay (<10% after five days) presumably due to the reduction of free volume in the closely packed nanocomposite film. © 1997 American Institute of Physics.
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85.40.Hp Lithography, masks and pattern transfer
81.07.-b Nanoscale materials and structures: fabrication and characterization
81.16.-c Methods of micro- and nanofabrication and processing
85.35.-p Nanoelectronic devices
68.35.B- Structure of clean surfaces (and surface reconstruction)
81.65.Cf Surface cleaning, etching, patterning
82.50.-m Photochemistry
61.48.-c Structure of fullerenes and related hollow and planar molecular structures
81.05.ub Fullerenes and related materials

Growth of CdTe/MnTe tilted and serpentine lattices on vicinal surfaces

J. M. Hartmann, M. Charleux, J. L. Rouvière, and H. Mariette

Appl. Phys. Lett. 70, 1113 (1997); http://dx.doi.org/10.1063/1.118501 (3 pages) | Cited 8 times

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We have grown by atomic layer epitaxy CdTe/MnTe tilted and serpentine superlattices. These heterostructures are formed by depositing in the step-flow growth mode fractional monolayer superlattices (CdTe)m(MnTe)n, with p = m+n ∼ 1, onto 2 °A and 2 °B Cd0.95Zn0.05Te vicinal substrates. Transmission electron microscopy images reveal a good in-plane CdTe/MnTe separation and a uniform short-range superlattice period. The very existence of those superlattices imply that Te-based vicinal surfaces present a regular array of monomolecular steps, with no important step meandering and no step bunching. © 1997 American Institute of Physics.
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68.65.-k Low-dimensional, mesoscopic, nanoscale and other related systems: structure and nonelectronic properties
81.15.Hi Molecular, atomic, ion, and chemical beam epitaxy
68.35.Ct Interface structure and roughness
68.35.B- Structure of clean surfaces (and surface reconstruction)
81.05.Dz II-VI semiconductors

Control of silicon nanocrystallite shape asymmetry and orientation anisotropy by light-assisted anodization

G. Polisski, B. Averboukh, D. Kovalev, and F. Koch

Appl. Phys. Lett. 70, 1116 (1997); http://dx.doi.org/10.1063/1.118502 (3 pages) | Cited 5 times

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It is shown that the different and conflicting results on the strength of polarization memory effect on porous Si result from the influence of light on the electrochemical etching process. Illumination in general reduces the memory effect by decreasing the particle shape asymmetry. Linearly polarized light can both enhance or reduce the effect. It is accompanied by an in-plane orientation anisotropy of the memory parameter for (100) porous Si. This effect is evidence for a preferential alignment of the crystallite asymmetry axis normal to the light polarization. © 1997 American Institute of Physics.
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81.65.-b Surface treatments
81.65.Cf Surface cleaning, etching, patterning
81.05.Rm Porous materials; granular materials
81.05.Cy Elemental semiconductors
81.07.-b Nanoscale materials and structures: fabrication and characterization
82.45.-h Electrochemistry and electrophoresis

Photopumped laser operation of an oxide post GaAs–AlAs superlattice photonic lattice

P. W. Evans, J. J. Wierer, and N. Holonyak

Appl. Phys. Lett. 70, 1119 (1997); http://dx.doi.org/10.1063/1.118480 (3 pages) | Cited 8 times

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Data are presented on the laser operation of photoexcited active hexagonal photonic lattices consisting of a GaAs–AlAs superlattice slab waveguide patterned with Zn-disordered AlGaAs posts that are converted to oxide. The semiconductor-oxide-post photonic lattice structure lases without the benefit of cleaved edges or other reflecting interfaces owing to strong local optical feedback provided by the high refractive index contrast between oxide posts and the active GaAs–AlAs superlattice. As the pump area is increased at constant pump power, the threshold intensity decreases as higher Q modes in an effectively larger cavity are excited. Similar hexagonal photonic lattices with nonoxidized posts (disordered AlGaAs posts) operate as lasers, but only with the assistance of cleaved edges and by shifting to longer wavelength. The oxide post photonic lattice is compatible with current-driven photonic lattice lasers or active filters.© 1997 American Institute of Physics.
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42.55.Px Semiconductor lasers; laser diodes
42.70.Qs Photonic bandgap materials
42.70.Hj Laser materials
78.66.Fd III-V semiconductors

Elastic moduli of gallium nitride

R. B. Schwarz, K. Khachaturyan, and E. R. Weber

Appl. Phys. Lett. 70, 1122 (1997); http://dx.doi.org/10.1063/1.118503 (3 pages) | Cited 66 times

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The second-order elastic constants of wurtzite phase GaN have been measured with 0.2% accuracy using a resonance ultrasound method. The measurements were done on a 0.29-mm-thick GaN crystal grown by chloride vapor-phase transport and subsequently detached from the substrate. The elastic moduli in units of GPa are: c11 = 377, c12 = 160, c13 = 114, c33 = 209, and c44 = 81.4. The elastic moduli are used to calculate the biaxial misfit stresses expected in heteroepitaxial thin films of GaN. © 1997 American Institute of Physics.
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62.20.D- Elasticity
68.60.Bs Mechanical and acoustical properties
81.05.Ea III-V semiconductors
81.40.Jj Elasticity and anelasticity, stress-strain relations

Hot carrier dynamics in a (GaInSb/InAs)/GaInAlAsSb superlattice multiple quantum well measured with mid-wave infrared, subpicosecond photoluminescence upconversion

D.-J. Jang, J. T. Olesberg, M. E. Flatté, Thomas F. Boggess, and T. C. Hasenberg

Appl. Phys. Lett. 70, 1125 (1997); http://dx.doi.org/10.1063/1.118504 (3 pages) | Cited 11 times

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We have extended the technique of subpicosecond photoluminescence upconversion to the mid-wave infrared spectral region and have used this system to investigate the energy relaxation of hot, optically injected electron-hole pairs in a narrow-band-gap (2.32 μm) (GaInSb/InAs)/ GaInAlAsSb superlattice multiple quantum well. These and similar structures are currently of interest as the active region for mid-wave infrared diode lasers. The measurements demonstrate that carriers, which are injected with nearly 1 eV of excess energy, are well described by a hot, thermalized distribution in the wells within 2 ps after excitation. For a carrier density of 1017 cm−3, cooling by optical phonon emission is essentially complete 15 ps after injection. By fitting the time dependence of the carrier temperature, we estimate an effective carrier- optical-phonon scattering time of 1.2 ps.© 1997 American Institute of Physics.
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73.40.Kp III-V semiconductor-to-semiconductor contacts, p-n junctions, and heterojunctions
72.20.Ht High-field and nonlinear effects
72.20.Jv Charge carriers: generation, recombination, lifetime, and trapping
73.61.Ey III-V semiconductors
78.55.Cr III-V semiconductors
78.47.-p Spectroscopy of solid state dynamics
63.20.K- Phonon interactions
71.38.-k Polarons and electron-phonon interactions
78.66.Fd III-V semiconductors

Delayed luminescence induced by intersubband optical excitation in a charge transfer double quantum well structure

M. Rüfenacht, S. Tsujino, Y. Ohno, and H. Sakaki

Appl. Phys. Lett. 70, 1128 (1997); http://dx.doi.org/10.1063/1.118505 (3 pages) | Cited 6 times

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Photoluminescence processes in a novel GaAs double quantum well (DQW) structure were studied and found to be controlled by a 10 μm mid-infrared (MIR) light. In this DQW structure, photogenerated electron-hole pairs are normally separated into different wells and their radiative recombination is inhibited. However, when a MIR light pulse is supplied to induce an electron intersubband transition, electrons are efficiently transferred to the hole-rich well, resulting in a significant enhancement of luminescence. By time shifting the MIR pulse with respect to the light pulse for interband excitation, we demonstrated the generation of a delayed photoluminescence. Device potentials of this MIR to near-infrared conversion are discussed. © 1997 American Institute of Physics.
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78.55.Cr III-V semiconductors
78.66.Fd III-V semiconductors
73.20.At Surface states, band structure, electron density of states
73.40.Kp III-V semiconductor-to-semiconductor contacts, p-n junctions, and heterojunctions

Electron spin relaxation in InGaAs/InP multiple-quantum wells

Atsushi Tackeuchi, Osamu Wada, and Yuji Nishikawa

Appl. Phys. Lett. 70, 1131 (1997); http://dx.doi.org/10.1063/1.118506 (3 pages) | Cited 50 times

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The electron spin relaxation of InGaAs/InP multiple-quantum wells (MQW) is investigated using time-resolved polarization-dependent absorption measurement. The MQW has an excitonic absorption at 1.54 μm which is suitable for application in optical communications. A theoretical prediction assuming the D’yakonov-Perel’ interaction as the main relaxation mechanism gives a spin relaxation rate for the InGaAs quantum well over twice as high as that for the GaAs quantum well. The spin relaxation time measured at room temperature is 5.2 ps and found to be an order of magnitude faster than that of a GaAs quantum well.© 1997 American Institute of Physics.
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76.70.Hb Optically detected magnetic resonance (ODMR)
76.30.-v Electron paramagnetic resonance and relaxation
71.35.Cc Intrinsic properties of excitons; optical absorption spectra
78.47.-p Spectroscopy of solid state dynamics
78.66.Fd III-V semiconductors

Evaluation of strained InGaAs/GaAs quantum wells by atomic force microscopy

M. Sato, U. Zeimer, F. Bugge, S. Gramlich, and M. Weyers

Appl. Phys. Lett. 70, 1134 (1997); http://dx.doi.org/10.1063/1.118507 (3 pages) | Cited 1 time

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Atomic force microscopy (AFM) is adopted for evaluation of strained InGaAs/GaAs quantum well structures grown by metalorganic vapor phase epitaxy. InAs-rich clusters are formed at the upper interface when the structure is grown with excessive supply of the In precursor. The defects arising from the clusters are clearly observed as convex domains from the irregularity of monolayer steps. The density of the convex domains coincides with the dark spot density measured by cathodoluminescence. Photoluminescence intensity is drastically reduced at high density of this type of defects. Thus, AFM measurements are able not only to give information on the structural quality but also to provide an estimation of the optical quality of such InGaAs/GaAs structures.© 1997 American Institute of Physics.
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68.65.-k Low-dimensional, mesoscopic, nanoscale and other related systems: structure and nonelectronic properties
81.05.Ea III-V semiconductors
72.80.Ey III-V and II-VI semiconductors
73.21.-b Electron states and collective excitations in multilayers, quantum wells, mesoscopic, and nanoscale systems
73.61.Ey III-V semiconductors
85.35.Be Quantum well devices (quantum dots, quantum wires, etc.)
68.35.B- Structure of clean surfaces (and surface reconstruction)
81.15.Kk Vapor phase epitaxy; growth from vapor phase
78.60.Hk Cathodoluminescence, ionoluminescence
78.55.Cr III-V semiconductors
78.66.Fd III-V semiconductors
68.55.Ln Defects and impurities: doping, implantation, distribution, concentration, etc.
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