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9 Jun 1997

Volume 70, Issue 23, pp. 3069-3169

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Electro-optic detection of THz radiation in LiTaO3, LiNbO3 and ZnTe

C. Winnewisser, P. Uhd Jepsen, M. Schall, V. Schyja, and H. Helm

Appl. Phys. Lett. 70, 3069 (1997); http://dx.doi.org/10.1063/1.119093 (3 pages) | Cited 44 times

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Freely propagating THz pulses are detected in electro-optic (eo) crystals by monitoring the phase retardation (PR) of an infrared femtosecond probe pulse. This technique permits the determination of the temporal shape of the THz pulse in the subpicosecond time domain. We present measurements in LiTaO3, LiNbO3, and ZnTe and compare their signal performance as eo crystals with theoretical calculations for the PR signal. ZnTe shows the best performance for eo detection. © 1997 American Institute of Physics.
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42.65.Re Ultrafast processes; optical pulse generation and pulse compression
78.20.Jq Electro-optical effects
07.57.Kp Bolometers; infrared, submillimeter wave, microwave, and radiowave receivers and detectors

Infrared spectroscopy of hydrides on the 6H-SiC surface

H. Tsuchida, I. Kamata, and K. Izumi

Appl. Phys. Lett. 70, 3072 (1997); http://dx.doi.org/10.1063/1.119094 (3 pages) | Cited 18 times

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Hydrides on the 6H-SiC(000math) and (0001) surfaces before and after hydrogen annealing were investigated by infrared attenuated total reflection spectroscopy. The absorption bands of CH2 and CH3 were observed from the 6H-SiC(000math) and (0001) surfaces before hydrogen annealing. After hydrogen annealing, a sharp C–H stretching vibration attributable to a monohydride appeared on the 6H-SiC(000math) surface, in contrast to a sharp Si–H stretching vibration which can be observed on the 6H-SiC(0001) surface. © 1997 American Institute of Physics.
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68.03.Fg Evaporation and condensation of liquids
68.43.Mn Adsorption kinetics
82.80.Ms Mass spectrometry (including SIMS, multiphoton ionization and resonance ionization mass spectrometry, MALDI)
81.05.Je Ceramics and refractories (including borides, carbides, hydrides, nitrides, oxides, and silicides)

Laser magnetometer measurement of the natural remanent magnetization of rocks

Jean-Charles Cotteverte, Jérôme Poirson, Albert Le Floch, Fabien Bretenaker, and Annick Chauvin

Appl. Phys. Lett. 70, 3075 (1997); http://dx.doi.org/10.1063/1.119095 (3 pages) | Cited 1 time

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The ability of a laser magnetometer to measure the natural remanent magnetization of rocks is experimentally investigated. It is shown that the performance of such a magnetometer permits the rapid measurement of rock magnetizations of less than 1 A m−1 in a laboratory without the need of any magnetic shielding or cryogenic facilities. Moreover, the laser magnetometer is experimentally shown to be able to measure the distribution of magnetization in spatially inhomogeneous samples. © 1997 American Institute of Physics.
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42.62.-b Laser applications
07.55.Jg Magnetometers for susceptibility, magnetic moment, and magnetization measurements
91.25.Ng Paleomagnetism
91.60.Pn Magnetic and electrical properties

Second harmonic generation in electric poled X-cut MgO-doped LiNbO3 waveguides

Shinichiro Sonoda, Isao Tsuruma, and Masami Hatori

Appl. Phys. Lett. 70, 3078 (1997); http://dx.doi.org/10.1063/1.119096 (3 pages) | Cited 18 times

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We demonstrate that quasi-phase-matched second harmonic generation occurs in annealed proton-exchanged (APE) X-cut MgO 5 mol % doped LiNbO3 (MgO:LN) waveguides supporting a TE-mode guided wave. Formation of a domain inversion was achieved by applying electric fields in X-cut and Y-cut MgO:LN. The depth of the formed domain inversion was 1 μm with a period of 4.75 μm. Anomalous characteristics of current versus voltage (I–V) of samples having domain inversion formed therein were found to have similar properties to a diode. A blue light having a wavelength of 475 nm and a power of 2.2 mW has been obtained with a normalized second harmonic conversion efficiency of 60%/W cm2 with uniform grating of 6 mm by using a Ti:Al2O3 laser as a fundamental wave source. © 1997 American Institute of Physics.
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42.65.Ky Frequency conversion; harmonic generation, including higher-order harmonic generation
42.79.Gn Optical waveguides and couplers
77.84.Ek Niobates and tantalates
77.84.Cg PZT ceramics and other titanates

Three-dimensional imaging of spin polarization of alkali-metal vapor in optical pumping cells

A. R. Young, S. Appelt, A. Ben-Amar Baranga, C. Erickson, and W. Happer

Appl. Phys. Lett. 70, 3081 (1997); http://dx.doi.org/10.1063/1.119097 (3 pages) | Cited 13 times

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We present detailed images of the Rb polarization in a high-pressure optical pumping cell. Images taken at high magnetic field strengths (≈37 G) yield precise information on the relative occupation probability of the hyperfine Zeeman sublevels. Low-field (⩽4 G) images yield very high resolution (less than 1 mm) maps of the spatial distribution of the Rb polarization. For optical pumping in the presence of high-pressure buffer gases, the measured populations of the hyperfine magnetic sublevels are shown to be well described by a spin temperature, even though the Rb–Rb spin exchange rate is much smaller than the rates of optical pumping or electron-randomizing Rb–Xe collisions in the buffer gas. © 1997 American Institute of Physics.
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32.80.Xx Level crossing and optical pumping
32.60.+i Zeeman and Stark effects
32.30.-r Atomic spectra

Avalanche upconversion in Er3+ doped fluoroindate glass

N. Rakov, Cid B. de Araújo, Y. Messaddeq, and M. A. Aegerter

Appl. Phys. Lett. 70, 3084 (1997); http://dx.doi.org/10.1063/1.119098 (3 pages) | Cited 16 times

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Avalanche upconversion is reported for Er3+ doped fluoroindate glass pumped at 633.5 nm. Strong frequency upconversion signals and intensity dependent transmittances are observed. The results of the transient and steady-state measurements agree well with the predictions of a rate-equation model which take into account cross-relaxation processes among pairs of erbium ions. © 1997 American Institute of Physics.
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42.70.Hj Laser materials
78.55.Hx Other solid inorganic materials
78.35.+c Brillouin and Rayleigh scattering; other light scattering

Sound-echo experiments in (100)-cut diamond at 70 and 150 GHz

B. Scheffold and O. Weis

Appl. Phys. Lett. 70, 3087 (1997); http://dx.doi.org/10.1063/1.119099 (3 pages)

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We report on sound-echo experiments at 70 and 150 GHz using a 3-mm-thick type IIa diamond with a (100) cut. Longitudinal sound was piezoelectrically excited and detected by means of a sputtered ZnO film. The method of linear frequency modulation of a continuous wave was applied. The temperature dependence of sound attenuation could be measured at 70 GHz up to a temperature of 200 K where an attenuation of about 1 dB/mm was observed. © 1997 American Institute of Physics.
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43.35.Fj Ultrasonic relaxation processes in gases, liquids, and solids
62.65.+k Acoustical properties of solids
07.64.+z Acoustic instruments and equipment

Modification of the density profile in a toroidal plasma source using a bias electric field

B. C. Zhang and R. C. Cross

Appl. Phys. Lett. 70, 3090 (1997); http://dx.doi.org/10.1063/1.119100 (3 pages) | Cited 1 time

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As in other plasma devices with a curved magnetic field geometry, an asymmetric density profile is observed in the PLADEPUS, a toroidal plasma source, at the University of Sydney. In this letter, we demonstrate that the asymmetric density profile can be improved by means of a positive bias electric field at the edge of the plasma. With the bias field, the density profile becomes symmetric and broadened, and the plasma density is enhanced. © 1997 American Institute of Physics.
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52.50.Dg Plasma sources
52.70.Ds Electric and magnetic measurements
52.77.Bn Etching and cleaning
52.77.Dq Plasma-based ion implantation and deposition

Effect of magnetic field on breakdown voltage characteristics of a multigap pseudospark

D. Sriram and K. K. Jain

Appl. Phys. Lett. 70, 3093 (1997); http://dx.doi.org/10.1063/1.119101 (3 pages) | Cited 1 time

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An experimental investigation of the effect of magnetic field on the breakdown voltage characteristics of a multigap pseudospark device, with hydrogen gas, in a hollow anode–cathode, as well as a hollow cathode–anode configuration, is presented. The breakdown pressure at a particular discharge voltage increases with the increase in the applied axial magnetic field, and the magnitude of the increase is more pronounced at lower discharge voltages causing a right shift to the characteristic discharge curve in both the configurations. Application of a transverse magnetic field also resulted in a shift of the characteristic discharge curve towards the right. The observed results are compared and discussed with that found for parallel electrode geometry. © 1997 American Institute of Physics.
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52.80.Mg Arcs; sparks; lightning; atmospheric electricity
52.75.-d Plasma devices

H2 damage of ferroelectric Pb(Zr,Ti)O3 thin-film capacitors—The role of catalytic and adsorptive activity of the top electrode

Y. Shimamoto, K. Kushida-Abdelghafar, H. Miki, and Y. Fujisaki

Appl. Phys. Lett. 70, 3096 (1997); http://dx.doi.org/10.1063/1.119102 (2 pages) | Cited 82 times

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Large-scale integrated fabrication in a H2 containing atmosphere, for example, during the passivation process, can cause serious damage in metal/Pb(Zr,Ti)O3/metal capacitors (i.e., Pt/PZT/Pt capacitors). To reveal the cause of the H2 damage, we investigated the behavior of hysteresis curves and the leakage current of capacitors with a top electrode of Pt, Pd, Au, or Ag. Capacitors with a top electrode of Au or Ag are more resistant to the H2 annealing damage than those of Pt or Pd. We found that the H2 damage was strongly affected by the catalytic activity and adsorptive properties of the top electrode when exposed to H2. © 1997 American Institute of Physics.
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77.55.-g Dielectric thin films
85.50.-n Dielectric, ferroelectric, and piezoelectric devices
82.65.+r Surface and interface chemistry; heterogeneous catalysis at surfaces

Ion milling damage and regrowth of oxide substrates studied by ion channeling and atomic force microscopy

I. Takeuchi, R. P. Sharma, S. Choopun, C. J. Lobb, and T. Venkatesan

Appl. Phys. Lett. 70, 3098 (1997); http://dx.doi.org/10.1063/1.119103 (3 pages) | Cited 3 times

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We have studied the effect of ion milling on the surface crystallinity of the metal oxide substrates LaAlO3, SrTiO3, and NdGaO3 which are used for fabrication of high-Tc Josephson junctions and circuits. Ion channeling of the milled substrates reveals a damage-induced peak corresponding to a disordered layer of ≈ 60 Å at the surface. Annealing the substrates in oxygen ambient at various temperatures ranging from 600 to 1100 °C resulted in the regrowth of the damaged layer at the surface of the substrates as was indicated by the reduction in size of the surface peak observed in the channeled spectrum, as well as by formation of lattice steps as seen by atomic force microscopy. A significant reduction in the damage peak size and the formation of smooth completed lattice steps are seen only after annealing at temperatures ≥ 950 °C. © 1997 American Institute of Physics.
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61.80.Jh Ion radiation effects
61.85.+p Channeling phenomena (blocking, energy loss, etc.)
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
74.72.-h Cuprate superconductors

Atomic displacement processes in irradiated amorphous and crystalline silicon

K. Nordlund and R. S. Averback

Appl. Phys. Lett. 70, 3101 (1997); http://dx.doi.org/10.1063/1.119104 (3 pages) | Cited 6 times

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Ion beam mixing was investigated in crystalline and amorphous Si using molecular dynamics simulations. The magnitude of mixing was found to be larger in amorphous Si by a factor of about 2. The difference is attributed to local relaxation mechanisms occurring during the cooling down phase of the cascade. Comparison of mixing between Si and Al shows that short range structural order also has a significant influence on mixing. © 1997 American Institute of Physics.
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61.80.Jh Ion radiation effects
61.82.Fk Semiconductors
61.80.Az Theory and models of radiation effects

The effect of implantation temperature on the surface hardness, elastic modulus and Raman scattering in amorphous carbon

Deok-Hyung Lee, Hyukjae Lee, Byungwoo Park, David B. Poker, and Laura Riester

Appl. Phys. Lett. 70, 3104 (1997); http://dx.doi.org/10.1063/1.119092 (3 pages) | Cited 9 times

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Nitrogen implantation into amorphous carbon has been studied at various implantation temperatures by using 100 keV N+ at 5 μA and fluences of 2×1017 ions/cm2. The apparent surface hardness and elastic modulus from nanoindentation are well correlated with an asymmetric diffuse peak at around 1500 cm−1 and a broad band at ∼ 700 cm−1 in the Raman spectra. Both the enhanced strengths and Raman characteristics show very weak Arrhenius-type implantation-temperature dependence with activation enthalpies of approximately 20 meV in the temperature range 223−1073 K. © 1997 American Institute of Physics.
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61.72.up Other materials
68.60.Bs Mechanical and acoustical properties
68.35.Gy Mechanical properties; surface strains
81.05.Gc Amorphous semiconductors

Parallel fabrication and single-electron charging of devices based on ordered, two-dimensional phases of organically functionalized metal nanocrystals

Gil Markovich, Daniel V. Leff, Sung-Wook Chung, Hermes M. Soyez, Bruce Dunn, and James R. Heath

Appl. Phys. Lett. 70, 3107 (1997); http://dx.doi.org/10.1063/1.119105 (3 pages) | Cited 27 times

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A parallel technique for fabricating single-electron, solid-state capacitance devices from ordered, two-dimensional closest-packed phases of organically functionalized metal nanocrystals is presented. The nanocrystal phases were prepared as Langmuir monolayers and subsequently transferred onto Al-electrode patterned glass substrates for device construction. Alternating current impedance measurements were carried out to probe the single-electron charging characteristics of the devices under both ambient and 77 K conditions. Evidence of a Coulomb blockade and step structure reminiscent of a Coulomb staircase is presented. © 1997 American Institute of Physics.
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85.35.Gv Single electron devices
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
73.23.Hk Coulomb blockade; single-electron tunneling

Synthesis and characterization of Ag–C60 nanostructure film

J. G. Hou, Yan Wang, Wentao Xu, S. Y. Zhang, Zou Jian, and Y. H. Zhang

Appl. Phys. Lett. 70, 3110 (1997); http://dx.doi.org/10.1063/1.119106 (3 pages) | Cited 11 times

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A thin film structure with Ag nanocrystallites embedded in a polycrystalline C60 matrix was grown under high vacuum by codeposition of Ag and C60 onto the hot substrate. The structural and physical properties of the film were characterized by a transmission electron microscope and a Raman scattering spectrometer. The Ag nanoparticles were well dispersed and not aggregated. An ordered nanoscale C60 lattice was observed between the two adjacent Ag particles, and the Raman-active Ag(2) pentagonal-pinch mode of C60 shifted to lower frequency. These results imply a strong interfacial interaction and charge transfer from the Ag to the C60. © 1997 American Institute of Physics.
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61.46.-w Structure of nanoscale materials
81.15.-z Methods of deposition of films and coatings; film growth and epitaxy
81.07.-b Nanoscale materials and structures: fabrication and characterization
68.55.-a Thin film structure and morphology

Atomic layer graphoepitaxy for single crystal heterostructures

D. J. Wallis, N. D. Browning, S. Sivananthan, P. D. Nellist, and S. J. Pennycook

Appl. Phys. Lett. 70, 3113 (1997); http://dx.doi.org/10.1063/1.119107 (3 pages) | Cited 5 times

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Here we report a strategy for the growth of single crystal heterostructures that dramatically reduces the nucleation of defects at the film–substrate interface. The substrate surface is patterned through miscut and passivated to enable a single domain template layer to be grown. This template is incommensurate with, and weakly bonded to, the substrate. A single domain film can then be nucleated preferentially at step edges and grown on the template. This mechanism is demonstrated for CdTe on Si(100) and should be applicable to many other systems. © 1997 American Institute of Physics.
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81.15.Hi Molecular, atomic, ion, and chemical beam epitaxy
68.37.Hk Scanning electron microscopy (SEM) (including EBIC)
68.37.Lp Transmission electron microscopy (TEM)
68.35.Fx Diffusion; interface formation
81.10.Aj Theory and models of crystal growth; physics and chemistry of crystal growth, crystal morphology, and orientation

Chemical vapor deposition of titanium–silicon–nitride films

Paul Martin Smith and J. S. Custer

Appl. Phys. Lett. 70, 3116 (1997); http://dx.doi.org/10.1063/1.119108 (3 pages) | Cited 27 times

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Titanium–silicon–nitride films were grown by metal-organic chemical vapor deposition. At temperatures between 300 and 450 °C, tetrakis(diethylamido)titanium, ammonia, and silane react to form films with average compositions near the TiN–Si3N4 tie line and low impurity contents (C<1.5 at. %, H between 5 and 15 at. %, with no other impurities present). The film resistivity is a strong function of Si content in the films, ranging continuously from 400 μΩ cm for pure TiN up to 1 Ω cm for films with 25 at. % Si. Step coverages of approximately 75% on 0.35 μm, 3:1 aspect ratio trenches, and 35%–40% on 0.1 μm/10:1 trenches are found for films with resistivities below 1000 μΩ cm. These films are promising candidates for diffusion barriers in microelectronic applications. © 1997 American Institute of Physics.
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81.15.Gh Chemical vapor deposition (including plasma-enhanced CVD, MOCVD, ALD, etc.)
81.05.Je Ceramics and refractories (including borides, carbides, hydrides, nitrides, oxides, and silicides)
68.55.Nq Composition and phase identification
66.30.Ny Chemical interdiffusion; diffusion barriers

Evidence of annealing effects on a high-density Si/SiO2 interfacial layer

S. D. Kosowsky, P. S. Pershan, K. S. Krisch, J. Bevk, M. L. Green, D. Brasen, L. C. Feldman, and P. K. Roy

Appl. Phys. Lett. 70, 3119 (1997); http://dx.doi.org/10.1063/1.119090 (3 pages) | Cited 32 times

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Thermally grown Si(001)/SiO2 samples were studied by x-ray reflectivity. Fits of model electron density profiles to the data reveal the existence of an interfacial layer at the Si/SiO2 interface up to 15-Å-thick, with density higher than either the crystalline Si or the main oxide layer. This density of the layer is reduced by a postoxidation anneal. © 1997 American Institute of Physics.
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68.55.-a Thin film structure and morphology
61.05.cm X-ray reflectometry (surfaces, interfaces, films)
68.35.Ct Interface structure and roughness

Synthesis of gallium nitride quantum dots through reactive laser ablation

Timothy J. Goodwin, Valerie J. Leppert, Subhash H. Risbud, Ian M. Kennedy, and Howard W. H. Lee

Appl. Phys. Lett. 70, 3122 (1997); http://dx.doi.org/10.1063/1.119109 (3 pages) | Cited 19 times

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Nanocrystalline GaN was synthesized through reactive laser ablation of gallium metal in a N2 atmosphere. X-ray diffraction, selected-area electron diffraction, and transmission electron microscopy measurements show that the GaN crystallites are as small as 2 nm in diameter, and follow a log-normal size distribution with a mean particle diameter of 12 nm. Size-selective photoluminescence and photoluminescence excitation spectroscopy reveal a continuous range of blueshifted band-edge emissions and absorptions starting from the bulk value for gallium nitride and continuing to below 300 nm. These results are consistent with a GaN particle size distribution that encompasses regions above and below the excitonic-Bohr radius of GaN, such that the GaN material shows combined bulk and quantum confined optical properties. © 1997 American Institute of Physics.
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81.15.Fg Pulsed laser ablation deposition
81.05.Ea III-V semiconductors
81.05.ub Fullerenes and related materials
61.05.jm Convergent-beam electron diffraction, selected-area electron diffraction, nanodiffraction

Suppression of boron transient enhanced diffusion in SiGe heterojunction bipolar transistors by carbon incorporation

L. D. Lanzerotti, J. C. Sturm, E. Stach, R. Hull, T. Buyuklimanli, and C. Magee

Appl. Phys. Lett. 70, 3125 (1997); http://dx.doi.org/10.1063/1.119110 (3 pages) | Cited 24 times

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In this work, we demonstrate that the incorporation of carbon in the base of a npn Si/SiGe/Si heterojunction bipolar transistor dramatically reduces the outdiffusion of boron from the base under postgrowth implantation and annealing procedures. Without the addition of C, these processes would lead to transistors with vastly degraded transistor characteristics. This reduction in B diffusion, when compared to devices without C, has been observed by both secondary ion mass spectroscopy and improved electrical characteristics. © 1997 American Institute of Physics.
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66.30.J- Diffusion of impurities
85.40.Ry Impurity doping, diffusion and ion implantation technology
85.30.Tv Field effect devices

Determination of significant transport parameters of two-dimensional electron gas systems by microwave methods

A. Brensing, M. Mazloom-Tehrani, and W. Bauhofer

Appl. Phys. Lett. 70, 3128 (1997); http://dx.doi.org/10.1063/1.119205 (3 pages) | Cited 1 time

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The main transport parameters of a two-dimensional electron gas (2DEG) system, namely, the effective mass m∗, electron sheet concentration ns, transport lifetime τc, and quantum lifetime τq, were determined exclusively by contactless microwave transmission methods in the frequency range 26.5–40 GHz. Shubnikov–de Haas oscillations were detected by measuring σxx with parallel waveguides while crossed waveguides were used for Hall measurements. The microwave results are in good agreement with values obtained from conventional direct current investigations. The 2DEG is realized in a modulation doped InGaAs/InP double heterostructure. © 1997 American Institute of Physics.
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73.61.-r Electrical properties of specific thin films
73.50.-h Electronic transport phenomena in thin films

Temperature dependence of the photoquenching of EL2 in semi-insulating GaAs

A. Alvarez, J. Jiménez, M. A. González, and L. F. Sanz

Appl. Phys. Lett. 70, 3131 (1997); http://dx.doi.org/10.1063/1.119111 (3 pages) | Cited 2 times

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A model of the temperature behavior of the photoquenching of EL2 in semi-insulating GaAs is presented. The thermal emission of a hole trapped on an actuator level accounts for the very low photoquenching efficiency above 85 K. This effect is presented in terms of a set of rate equations that reproduce in a reliable way the temperature dependence of the photoquenching of EL2. The activation energy of the actuator level suggests a hole trap level other than GaAs as was previously assumed. © 1997 American Institute of Physics.
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71.55.Eq III-V semiconductors
72.40.+w Photoconduction and photovoltaic effects

Misfit dislocations generated from inhomogeneous sources and their critical thicknesses in a InGaAs/GaAs heterostructure grown by molecular beam epitaxy

J. Zou, D. J. H. Cockayne, and J. J. Russell-Harriott

Appl. Phys. Lett. 70, 3134 (1997); http://dx.doi.org/10.1063/1.119112 (3 pages) | Cited 9 times

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Misfit dislocations generated from inhomogeneous sources in InGaAs/GaAs strained-layer heterostructures grown by molecular beam epitaxy were investigated using transmission electron microscopy (TEM) with the lift-off technique. These inhomogeneous sources are suggested to be particulates. TEM investigations show that (1) the critical thicknesses of misfit dislocations generated from inhomogeneous sources are the same as those generated from preexisting threading dislocations, and (2) each inhomogeneous source may generate a number of misfit dislocations. These observations suggest that these inhomogeneous sources are a prime source of misfit dislocation generation. © 1997 American Institute of Physics.
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61.72.Ff Direct observation of dislocations and other defects (etch pits, decoration, electron microscopy, x-ray topography, etc.)
68.35.Dv Composition, segregation; defects and impurities
68.55.Ln Defects and impurities: doping, implantation, distribution, concentration, etc.

Effects of V/III ratio on ordering and antiphase boundaries in GaInP layers

Tae-Yeon Seong, Joon Hyung Kim, Y. S. Chun, and G. B. Stringfellow

Appl. Phys. Lett. 70, 3137 (1997); http://dx.doi.org/10.1063/1.119113 (3 pages) | Cited 6 times

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Transmission electron microscope (TEM) and transmission electron diffraction (TED) studies have been performed to investigate the effects of V/III ratio on ordering and antiphase boundaries (APBs) in organometallic vapor phase epitaxial Ga0.5In0.5P layers grown onto (001) GaAs vicinal substrates at 670 °C. TED and TEM examination showed that the degree of order is higher in the layer grown using a V/III ratio of 160 than in the layer grown using a V/III ratio of 40. TEM results showed that the higher V/III ratio could be used to suppress APBs. In addition, the growth of order-induced heterostructures, where the V/III ratio is increased abruptly during growth, could be used to block the propagation of APBs. Mechanisms are proposed to explain these phenomena. © 1997 American Institute of Physics.
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68.55.-a Thin film structure and morphology
68.37.Hk Scanning electron microscopy (SEM) (including EBIC)
68.37.Lp Transmission electron microscopy (TEM)
61.05.jm Convergent-beam electron diffraction, selected-area electron diffraction, nanodiffraction

Growth patterns of self-assembled InAs quantum dots near the two-dimensional to three-dimensional transition

M. Colocci, F. Bogani, L. Carraresi, R. Mattolini, A. Bosacchi, S. Franchi, P. Frigeri, M. Rosa-Clot, and S. Taddei

Appl. Phys. Lett. 70, 3140 (1997); http://dx.doi.org/10.1063/1.119114 (3 pages) | Cited 29 times

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Self-assembled InAs quantum dots have been grown by molecular beam epitaxy in such a way as to obtain a continuous variation of InAs coverages across the wafer. Structured photoluminescence spectra are observed after excitation of a large number of dots; deconvolution into Gaussian components yields narrow emission bands (full width at half-maximum 20–30 meV) separated in energy by an average spacing of 30–40 meV. We ascribe the individual bands of the photoluminescence spectra after low excitation to families of dots with similar shapes and with heights differing by one monolayer, as strongly supported by numerical calculations of the fundamental electronic transitions in quantum dot structures. © 1997 American Institute of Physics.
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81.15.Hi Molecular, atomic, ion, and chemical beam epitaxy
68.65.-k Low-dimensional, mesoscopic, nanoscale and other related systems: structure and nonelectronic properties
78.66.Fd III-V semiconductors
73.21.-b Electron states and collective excitations in multilayers, quantum wells, mesoscopic, and nanoscale systems
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