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8 Apr 2002

Volume 80, Issue 14, pp. 2433-2611

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Short-wavelength (λ<2 μm) intersubband absorption dynamics in ZnSe/BeTe quantum wells

R. Akimoto, K. Akita, F. Sasaki, and S. Kobayashi

Appl. Phys. Lett. 80, 2433 (2002); http://dx.doi.org/10.1063/1.1468261 (3 pages) | Cited 14 times

Online Publication Date: 2 April 2002

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We report on linear and nonlinear short-wavelength (λ<2 μm) intersubband (ISB) absorption characteristics in ZnSe/BeTe quantum wells by means of an interband pump and ISB pump/probe technique. The ISB absorption saturates with a hole burning effect, indicating the absorption band is broadened inhomogeneously. The saturation intensity is as low as 4.3 MW/cm2 at λ = 1.76 μm. The direct ISB energy relaxation time increases gradually from 0.20 to 0.38 ps with decreasing λ from 2.2 to 1.8 μm, while the saturation recovery is replaced by another slow relaxation process with a time constant of a few ps. The Γ(ZnSe)–X(BeTe) electron transfer is a relevant mechanism for this slow relaxation. © 2002 American Institute of Physics.
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73.21.Fg Quantum wells
78.67.De Quantum wells
78.47.-p Spectroscopy of solid state dynamics
42.50.Md Optical transient phenomena: quantum beats, photon echo, free-induction decay, dephasings and revivals, optical nutation, and self-induced transparency
78.40.Fy Semiconductors
42.50.Hz Strong-field excitation of optical transitions in quantum systems; multiphoton processes; dynamic Stark shift

Improved efficiency of light-emitting diodes based on polyfluorene blends upon insertion of a poly(p-phenylene vinylene) electron- confinement layer

J. Morgado, R. H. Friend, and F. Cacialli

Appl. Phys. Lett. 80, 2436 (2002); http://dx.doi.org/10.1063/1.1467981 (3 pages) | Cited 53 times

Online Publication Date: 2 April 2002

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We report the improvement of the electroluminescence efficiency of light-emitting diodes (LEDs) based on polyfluorene blends, upon insertion of a thin film of poly(p-phenylene vinylene), PPV, between a hole-injection layer of poly(3,4-ethylene dioxythiophene), doped with polystyrene sulfonic acid, and the polyfluorenes emissive layer. For LEDs using a blend of poly(9,9′-dioctylfluorene), with 5 wt % of the green emitter poly(9,9′-dioctylfluorene-altbenzothiadiazole), and calcium cathodes, the efficiency increases from 2.1 to 4.1 cd/A upon insertion of such a PPV layer. We propose that such an improvement is mainly due to the electron-blocking effect of the PPV layer, leading to improved charge carriers balance within the emissive layer. © 2002 American Institute of Physics.
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85.60.Jb Light-emitting devices
42.70.Jk Polymers and organics
78.66.Qn Polymers; organic compounds
78.60.Fi Electroluminescence

Optical recording using smectic layer rotation in ferroelectric liquid crystal

Keizo Nakayama, Junji Ohtsubo, Masanori Ozaki, and Katsumi Yoshino

Appl. Phys. Lett. 80, 2439 (2002); http://dx.doi.org/10.1063/1.1467972 (3 pages)

Online Publication Date: 2 April 2002

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Optical recording in a ferroelectric liquid crystal using smectic layer rotation induced by the application of asymmetric voltage pulses has been proposed. This recording method is based on the temperature dependence of the rotation rate and the fact that the rate in the smectic A (SmA) phase is considerably smaller than that in the chiral smectic C (SmC∗) phase. The transition from the SmC∗ to the SmA phase can be induced by the photothermal effect. The application of asymmetric voltage pulses during partial laser irradiation results in the patterning of the layer alignment. This recording method can erase and invert the stored pattern and can handle gray-level patterns. © 2002 American Institute of Physics.
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42.79.Vb Optical storage systems, optical disks
42.70.Df Liquid crystals
42.70.Ln Holographic recording materials; optical storage media
78.20.Jq Electro-optical effects
61.30.Gd Orientational order of liquid crystals; electric and magnetic field effects on order
77.80.-e Ferroelectricity and antiferroelectricity
77.84.Nh Liquids, emulsions, and suspensions; liquid crystals
64.70.M- Transitions in liquid crystals
85.50.Gk Non-volatile ferroelectric memories

Optical thin films consisting of nanoscale laminated layers

Shin-ichi Zaitsu, Takahisa Jitsuno, Masahiro Nakatsuka, Tatsuhiko Yamanaka, and Shinji Motokoshi

Appl. Phys. Lett. 80, 2442 (2002); http://dx.doi.org/10.1063/1.1467622 (3 pages) | Cited 15 times

Online Publication Date: 2 April 2002

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The control of the refractive index of laminated coatings consisting of alternating stacks of nanoscale Al2O3 and TiO2 sublayers grown by atomic layer deposition has been achieved. The refractive index of the coating linearly changed from 1.870 to 2.318 as the thickness of the single TiO2 sublayer was varied from 2.0 to 39 Å while that of the single Al2O3 sublayer was kept constant at 5.5 Å. The refractive index could be varied by adjusting only the number of growth cycles of each material. This approach will have potential applications to optical multilayer coatings consisting of well-controlled extremely thin layers. © 2002 American Institute of Physics.
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42.70.Nq Other nonlinear optical materials; photorefractive and semiconductor materials
78.20.Ci Optical constants (including refractive index, complex dielectric constant, absorption, reflection and transmission coefficients, emissivity)
68.65.Ac Multilayers
42.79.Wc Optical coatings
78.66.-w Optical properties of specific thin films
42.79.Ci Filters, zone plates, and polarizers

Low threshold 1.2 μm InGaAs quantum well lasers grown under low As/III ratio

T. Takeuchi, Y.-L. Chang, A. Tandon, D. Bour, S. Corzine, R. Twist, M. Tan, and H.-C. Luan

Appl. Phys. Lett. 80, 2445 (2002); http://dx.doi.org/10.1063/1.1467697 (3 pages) | Cited 18 times

Online Publication Date: 2 April 2002

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We have achieved 160 A/cm2 threshold current density of a 1.21 μm InGaAs/GaAs quantum well (QW) laser grown under a very low As/III ratio. We investigated the As/III ratio dependence on the optical quality of InGaAs QWs grown with arsine and tertiarybutylarsine (TBA). We found that TBA allows us to grow high quality InGaAs QWs under a very low As/III ratio (∼3), while a higher As/III ratio (∼10) with arsine is necessary to obtain the similar quality QWs. This high quality InGaAs QW grown under the low As/III ratio leads to the realization of high quality InGaAsN QW which should be grown under a low As/III ratio and a high N/V ratio. © 2002 American Institute of Physics.
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42.60.By Design of specific laser systems
81.07.St Quantum wells
42.55.Px Semiconductor lasers; laser diodes
78.67.De Quantum wells
81.15.Gh Chemical vapor deposition (including plasma-enhanced CVD, MOCVD, ALD, etc.)
78.55.Cr III-V semiconductors
85.35.Be Quantum well devices (quantum dots, quantum wires, etc.)

Quaternary GaInAsN with high In content: Dependence of band gap energy on N content

D. Serries, T. Geppert, P. Ganser, M. Maier, K. Köhler, N. Herres, and J. Wagner

Appl. Phys. Lett. 80, 2448 (2002); http://dx.doi.org/10.1063/1.1467612 (3 pages) | Cited 14 times

Online Publication Date: 2 April 2002

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Quaternary pseudomorphically strained GaInAsN films and double-quantum wells were grown by plasma assisted molecular-beam epitaxy on an InP substrate. The In content ranged from 53% to 70% while the N content was varied between 0% and 2.4%. A reduction of compressive strain and a low-energy shift of photoluminescence (PL) peak position was observed with increasing N concentration, accompanied by a reduction in PL peak intensity and increase in linewidth. The net effect of N incorporation on the GaInAsN band gap energy was calculated from the measured PL peak energies. The thus obtained composition dependent GaInAsN band gap energy was fitted using the band anticrossing model, yielding values for the interaction parameter CMN for high In-containing GaInAsN being only slightly smaller than that reported for low In-content GaInAsN on GaAs. © 2002 American Institute of Physics.
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73.21.Fg Quantum wells
78.67.De Quantum wells
78.55.Cr III-V semiconductors
71.55.Eq III-V semiconductors
71.20.Nr Semiconductor compounds

Theoretical investigation of laser gain in AlGaInN quaternary quantum wells

W. W. Chow, H. C. Schneider, A. J. Fischer, and A. A. Allerman

Appl. Phys. Lett. 80, 2451 (2002); http://dx.doi.org/10.1063/1.1465523 (3 pages) | Cited 4 times

Online Publication Date: 2 April 2002

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Microscopic calculations of laser gain spectra are presented for AlGaInN wurtzite quantum-well structures that are under compressive, zero and tensile strain. It is found that the optical nonlinearities induced by the combination of strain, quantum-confined Stark effect and many-body Coulomb interactions give rise to optical behavior that can differ significantly from that in conventional semiconductor lasers. © 2002 American Institute of Physics.
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42.55.Px Semiconductor lasers; laser diodes
78.67.De Quantum wells
42.65.-k Nonlinear optics
68.65.Fg Quantum wells
78.20.Jq Electro-optical effects
62.20.-x Mechanical properties of solids

Dual-frequency quantum-cascade terahertz emitter

V. M. Menon, W. D. Goodhue, A. S. Karakashian, A. Naweed, J. Plant, L. R. Ram-Mohan, A. Gatesman, V. Badami, and J. Waldman

Appl. Phys. Lett. 80, 2454 (2002); http://dx.doi.org/10.1063/1.1467698 (3 pages) | Cited 4 times

Online Publication Date: 2 April 2002

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We report the realization of a GaAs/AlGaAs quantum-cascade terahertz emitter capable of emitting at two entirely different frequencies from the same structure. This is realized through judicious wavefunction engineering of the relevant electronic states. Emission is observed at 6.32 meV (1.5 THz) and 12.18 meV (2.9 THz) with full width at half maximum of 0.72 meV and 0.58 meV, respectively, at T = 10 K. The structure consisted of 40 periods of the quantum-cascade module. Emission occurred between two sets of distinct energy levels that came into the desired configuration at different biases due to the quantum-confined Stark effect. Higher-energy AlAs-like phonons were utilized for the depopulation mechanism. © 2002 American Institute of Physics.
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42.55.Px Semiconductor lasers; laser diodes
78.67.De Quantum wells
85.35.Be Quantum well devices (quantum dots, quantum wires, etc.)
78.20.Jq Electro-optical effects
78.60.Fi Electroluminescence
73.21.Fg Quantum wells
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Angularly resolved measurements of ion energy of vacuum arc plasmas

André Anders and George Yu. Yushkov

Appl. Phys. Lett. 80, 2457 (2002); http://dx.doi.org/10.1063/1.1468271 (3 pages) | Cited 9 times

Online Publication Date: 2 April 2002

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The kinetic energy of ions generated by pulsed vacuum arcs was measured with angular resolution in the interval −90° to +90° with respect to the cathode normal. A current perturbation method in conjunction with drift time measurements was used. Cathode materials included C, Mg, Ti, Cu, Ag, Ta, and Pb with an average arc current of 300 A and 600 μs duration. The measured angular energy distributions are slightly peaked at the cathode normal. Each distribution can be fitted by a superposition of an isotropic component and a cosine function, with the isotropic component dominating. This result is in contrast to plasma jet formation observed by others, which is most likely due to effects of anode geometry and magnetic fields, including the self-field of the current-carrying plasma. © 2002 American Institute of Physics.
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52.80.Vp Discharge in vacuum
52.80.Mg Arcs; sparks; lightning; atmospheric electricity
52.30.-q Plasma dynamics and flow
52.70.Nc Particle measurements
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Microscopic structure and optical properties of GaAs1−xNx/GaAs(001) interface grown by metalorganic vapor phase epitaxy

H. Dumont, L. Auvray, Y. Monteil, C. Bondoux, L. Largeau, and G. Patriarche

Appl. Phys. Lett. 80, 2460 (2002); http://dx.doi.org/10.1063/1.1468272 (3 pages) | Cited 4 times

Online Publication Date: 2 April 2002

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We have investigated the structure and optical properties of GaAs0.97N0.03/GaAs produced by metalorganic vapor phase epitaxy grown on GaAs surface at 520–550 °C. Using cross-sectional transmission electron microscopy and photoluminescence spectroscopy (PL), we show the presence of a 5–6-nm-thick nitrogen-rich interfacial region. The nitrogen composition near the interface is twice higher (x = 0.038) than that of the bulk epilayer (x = 0.016). PL data shows two peaks located at 1.05 and 1.18 eV associated to the interfacial region and the bulk layer, respectively. We discuss several mechanisms of surface enrichment of nitrogen that occurred during the first stage of GaAsN growth. © 2002 American Institute of Physics.
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68.35.Ct Interface structure and roughness
78.66.Fd III-V semiconductors
81.05.Ea III-V semiconductors
68.35.Dv Composition, segregation; defects and impurities
78.55.Cr III-V semiconductors
81.15.Gh Chemical vapor deposition (including plasma-enhanced CVD, MOCVD, ALD, etc.)
68.37.Lp Transmission electron microscopy (TEM)
68.55.A- Nucleation and growth

Effect of film thickness on hydrogenated amorphous silicon grown with hydrogen diluted silane

P. Danesh, B. Pantchev, D. Grambole, and B. Schmidt

Appl. Phys. Lett. 80, 2463 (2002); http://dx.doi.org/10.1063/1.1467705 (3 pages) | Cited 12 times

Online Publication Date: 2 April 2002

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Thin films of hydrogenated amorphous silicon (a-Si:H) prepared by plasma-enhanced chemical vapor deposition with 10% SiH4 in hydrogen have been studied concerning the effect of film thickness on the hydrogen concentration, interconnected void network and mechanical stress. The hydrogen concentration was determined by nuclear reaction analysis. The interconnected void network was studied by the method of ion exchange in glass substrate. The films were prepared at a substrate temperature in the range of 150–270 °C. The results show that at the substrate temperature of 150 °C the film starts to grow with an extensive void network, and its structural improvement with thickness is manifested by an increase of the film density. In contrast, at 270 °C the film starts to grow with a dense structure, and its improvement is manifested by an increase of the intrinsic compressive stress. The hydrogen concentration does not depend on the film thickness at any substrate temperature. © 2002 American Institute of Physics.
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81.05.Gc Amorphous semiconductors
52.77.Dq Plasma-based ion implantation and deposition
68.55.A- Nucleation and growth
81.15.Gh Chemical vapor deposition (including plasma-enhanced CVD, MOCVD, ALD, etc.)
61.43.Dq Amorphous semiconductors, metals, and alloys
61.72.Qq Microscopic defects (voids, inclusions, etc.)
68.60.Bs Mechanical and acoustical properties
81.05.Cy Elemental semiconductors
82.80.-d Chemical analysis and related physical methods of analysis
68.55.Ln Defects and impurities: doping, implantation, distribution, concentration, etc.

High-frequency dispersion of ultrasonic velocity and attenuation of single-crystal 0.72 Pb(Mg1/3Nb2/3)O3–0.28 PbTiO3 with engineered domain structures

Wenhua Jiang, Wenwu Cao, and Pengdi Han

Appl. Phys. Lett. 80, 2466 (2002); http://dx.doi.org/10.1063/1.1468265 (3 pages) | Cited 6 times

Online Publication Date: 2 April 2002

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Using ultrasonic spectroscopy, the frequency dispersions of ultrasonic velocity and attenuation were measured for single crystal 0.72 Pb(Mg1/3Nb2/3)−0.28 PbTiO3 (PMN−28%PT) with engineered domain structures in the frequency range of 50–110 MHz. We found that the velocity dispersion and attenuation are very small for the longitudinal wave propagating along [001] of the pseudotetragonal state. Our results imply that the developed domain-engineered PMN-PT single crystals, which have extremely large d33 and k33, have great potential for high-frequency applications. © 2002 American Institute of Physics.
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77.84.Ek Niobates and tantalates
77.84.Cg PZT ceramics and other titanates
77.65.Dq Acoustoelectric effects and surface acoustic waves (SAW) in piezoelectrics
62.65.+k Acoustical properties of solids
77.80.Dj Domain structure; hysteresis

Mg-rich precipitates in the p-type doping of InGaN-based laser diodes

M. Hansen, L. F. Chen, S. H. Lim, S. P. DenBaars, and J. S. Speck

Appl. Phys. Lett. 80, 2469 (2002); http://dx.doi.org/10.1063/1.1467704 (3 pages) | Cited 22 times

Online Publication Date: 2 April 2002

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Uniformly distributed precipitates have been observed by transmission electron microscopy in the p-type layers of laser structures. The precipitate density decreases with decreasing flow of biscyclopentadienyl-magnesium (Cp2Mg), and the hole concentration in the laser structure was higher for a lower precipitate density. The higher hole concentration reduces the threshold current density and improves the internal quantum efficiency of the laser because of the higher number of holes available for radiative recombination. The lasers with higher precipitate density also exhibit a higher resistance. The threshold voltage was reduced 30% from 20.8 V for lasers with a high precipitate density to 14.3 V for lasers with a lower precipitate density due to the lower resistance. © 2002 American Institute of Physics.
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42.55.Px Semiconductor lasers; laser diodes
64.75.-g Phase equilibria
61.72.uj III-V and II-VI semiconductors

Si-doped cubic GaN grown on a Si(001) substrate with a thin flat SiC buffer layer

D. Wang, S. Yoshida, and M. Ichikawa

Appl. Phys. Lett. 80, 2472 (2002); http://dx.doi.org/10.1063/1.1467971 (3 pages) | Cited 3 times

Online Publication Date: 2 April 2002

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Highly Si-doped cubic GaN films were grown on a Si(001) substrate coated with a 2.5-nm-thick flat 3C–SiC buffer layer. The Si doping concentration ranged from 1×1019 to 1×1021 cm−3. Upon Si doping, the initial nucleations easily coalesced, producing a flat surface with a 4×1 reconstruction and preferential growth in the [110] direction. The density of stacking faults also increased. The substitution of Ga atoms with Si atoms and the increased density of stacking faults help to relieve the compressive stress in GaN caused by the lattice mismatch of the GaN film and the substrate. GaN showed a strong photoluminescence intensity at room temperature. © 2002 American Institute of Physics.
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81.15.Hi Molecular, atomic, ion, and chemical beam epitaxy
68.55.A- Nucleation and growth
78.55.Cr III-V semiconductors
78.66.Fd III-V semiconductors
81.05.Ea III-V semiconductors
68.60.Bs Mechanical and acoustical properties
61.72.S- Impurities in crystals
61.72.Nn Stacking faults and other planar or extended defects
68.35.B- Structure of clean surfaces (and surface reconstruction)

Effect of H2 on nitrogen incorporation in the metalorganic chemical vapor deposition of GaAs1−yNy (0 ⩽ y ⩽ 0.08)

B. F. Moody, P. T. Barletta, N. A. El-Masry, J. C. Roberts, M. E. Aumer, S. F. LeBoeuf, and S. M. Bedair

Appl. Phys. Lett. 80, 2475 (2002); http://dx.doi.org/10.1063/1.1464225 (3 pages) | Cited 3 times

Online Publication Date: 2 April 2002

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The effect of hydrogen on the incorporation of nitrogen in GaAs1−yNy grown by metalorganic chemical vapor deposition (MOCVD) is reported. Nitrogen content as high as y = 0.081 has been achieved when the use of H2 is completely avoided in the MOCVD growth of GaAs1−yNy. When H2 is added to the growth ambient, the value of y in GaAs1−yNy decreases as the relative percent of H2 in the carrier gas increases. We will report on the properties of these GaAsN films and discuss the nature of the effect that H2 has on modulating the N content in these films. © 2002 American Institute of Physics.
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81.15.Gh Chemical vapor deposition (including plasma-enhanced CVD, MOCVD, ALD, etc.)
68.55.A- Nucleation and growth
81.05.Ea III-V semiconductors
81.15.Kk Vapor phase epitaxy; growth from vapor phase

ZrNbCuNiAl bulk metallic glass matrix composites containing dendritic bcc phase precipitates

U. Kühn, J. Eckert, N. Mattern, and L. Schultz

Appl. Phys. Lett. 80, 2478 (2002); http://dx.doi.org/10.1063/1.1467707 (3 pages) | Cited 156 times

Online Publication Date: 2 April 2002

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We report on phase formation of a multicomponent Zr66.4Nb6.4Cu10.5Ni8.7Al8 glass-forming alloy upon copper mold casting. A bcc phase embedded in a glassy matrix forms for moldcast bulk samples yielding an in-situ bulk metallic glass matrix composite upon slow cooling from the melt. Upon annealing, the first exothermic transformation of the material is related to precipitation of an icosahedral phase from the glassy matrix. The formation of the bcc phase-containing metallic glass composite is strongly governed by the alloy composition and the actual cooling rate during solidification. Room-temperature compression tests reveal significant yielding and plastic deformation before failure. © 2002 American Institute of Physics.
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61.43.Fs Glasses
81.30.Mh Solid-phase precipitation
62.20.F- Deformation and plasticity
81.40.Gh Other heat and thermomechanical treatments
64.75.-g Phase equilibria
81.40.Lm Deformation, plasticity, and creep
62.20.M- Structural failure of materials
81.40.Np Fatigue, corrosion fatigue, embrittlement, cracking, fracture, and failure
61.44.Br Quasicrystals

Strain-induced anisotropic Ge diffusion in SiGe/Si superlattices

Y. S. Lim, J. Y. Lee, H. S. Kim, and D. W. Moon

Appl. Phys. Lett. 80, 2481 (2002); http://dx.doi.org/10.1063/1.1465500 (3 pages) | Cited 5 times

Online Publication Date: 2 April 2002

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Anisotropic diffusion of Ge induced by nonuniform strain in SiGe/Si interfaces in the range of 700–850 °C is directly observed with medium-energy ion-scattering spectroscopy through its composition and strain profiles of atomic-layer depth resolution. For SiGe/Si interfaces with identical composition profiles but with different strain distributions, the anisotropic diffusion of Ge can be clearly correlated with the anisotropic relaxation of the nonuniform strain in the near-surface layer of several nm depth. The results suggest that atomic-scale strain control is critical to maintain abrupt SiGe/Si interfaces under thermal budget. © 2002 American Institute of Physics.
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68.65.Cd Superlattices
68.35.Fx Diffusion; interface formation
68.35.Ct Interface structure and roughness
68.49.Sf Ion scattering from surfaces (charge transfer, sputtering, SIMS)
79.20.Rf Atomic, molecular, and ion beam impact and interactions with surfaces

Phonon wave-packet dynamics at semiconductor interfaces by molecular-dynamics simulation

P. K. Schelling, S. R. Phillpot, and P. Keblinski

Appl. Phys. Lett. 80, 2484 (2002); http://dx.doi.org/10.1063/1.1465106 (3 pages) | Cited 56 times

Online Publication Date: 2 April 2002

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We directly observe phonon wave packets of well-defined frequency and polarization scattering at a coherent semiconductor interface using molecular-dynamics simulations. We find that in the low-frequency limit the transmission coefficients of both longitudinal and transverse acoustic phonons agree well with those predicted by the continuum-level based acoustic mismatch model. However, the transmission coefficients rapidly decrease close to the cutoff frequency, a result that can be understood within a simple one-dimensional discrete atomic-chain model. We also find that the transmission coefficient for transverse acoustic phonons depends strongly on the relative orientation of the polarization and the Si–Si bonds in the diamond lattice structure. © 2002 American Institute of Physics.
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68.35.Ja Surface and interface dynamics and vibrations

Interaction of electron and hole plasma with coherent longitudinal optical phonons in GaAs

Y.-M. Chang

Appl. Phys. Lett. 80, 2487 (2002); http://dx.doi.org/10.1063/1.1466535 (3 pages) | Cited 13 times

Online Publication Date: 2 April 2002

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The interaction of photoexcited electron–hole plasma with impulsively excited coherent longitudinal optical phonons in GaAs was investigated via time-resolved second-harmonic generation. The dephasing time of coherent LO phonons reduces significantly as photoexcited electron–hole plasma is injected into the near-surface depletion region. The coherent LO-electron and LO-hole coupling modes can both be clearly observed and investigated in real time. The rapid dephasing of the coherent LO-hole coupling mode is attributed to the strong polar phonon-carrier interaction and the overdamped nature of hole plasma. © 2002 American Institute of Physics.
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63.20.K- Phonon interactions
42.65.Ky Frequency conversion; harmonic generation, including higher-order harmonic generation
78.47.-p Spectroscopy of solid state dynamics
72.30.+q High-frequency effects; plasma effects
72.80.Ey III-V and II-VI semiconductors

Normal-incidence voltage-tunable middle- and long-wavelength infrared photoresponse in self-assembled InAs quantum dots

Zhonghui Chen, Eui-Tae Kim, and Anupam Madhukar

Appl. Phys. Lett. 80, 2490 (2002); http://dx.doi.org/10.1063/1.1467974 (3 pages) | Cited 42 times

Online Publication Date: 2 April 2002

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We report the realization of electron intraband absorption based middle- (∼5.6 μm) and long- (∼10 μm) wavelength infrared (IR) photoresponse for normally incident radiation on InGaAs-capped GaAs(001)/InAs quantum dots (QDs) in a n–i(QD)–n structure. The relative photoresponse in this dual-wavelength structure is tunable up to two orders of magnitude with bias. The full width at half maximum of the long-wavelength IR intraband photocurrent peak at 80 K is as narrow as 8.2 meV. © 2002 American Institute of Physics.
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81.07.Ta Quantum dots
72.40.+w Photoconduction and photovoltaic effects
73.63.Kv Quantum dots
73.61.Ey III-V semiconductors
81.05.Ea III-V semiconductors
73.50.Pz Photoconduction and photovoltaic effects
07.57.Kp Bolometers; infrared, submillimeter wave, microwave, and radiowave receivers and detectors
85.60.Gz Photodetectors (including infrared and CCD detectors)
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Polarization charges at spontaneously ordered (In, Ga)P/GaAs interfaces

P. Krispin, A. Knauer, and S. Gramlich

Appl. Phys. Lett. 80, 2493 (2002); http://dx.doi.org/10.1063/1.1467978 (3 pages) | Cited 3 times

Online Publication Date: 2 April 2002

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The depth-resolved electrical characteristics of n- and p-type GaAs/(In, Ga)P/GaAs heterojunctions are examined by capacitance–voltage measurements. Different epitaxial growth conditions are chosen to produce heterointerfaces with (In, Ga)P layers of various degrees of order. Irrespective of the conduction type of the heterojunction studied, we find positive [negative] sheet charges at the (In, Ga)P-on-GaAs [GaAs-on-(In, Ga)P] interfaces. The density of both interfacial charges increases with increasing degree of (In, Ga)P order. The experimental results can be completely explained by taking into account the spontaneous polarization of ordered (In, Ga)P. The polarization difference between ordered (In, Ga)P and GaAs (no polarization) results in opposite sheet charges at the two complementary interfaces with GaAs, in accordance with theoretical predictions. © 2002 American Institute of Physics.
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73.40.Kp III-V semiconductor-to-semiconductor contacts, p-n junctions, and heterojunctions
77.22.Ej Polarization and depolarization

Room-temperature 1.54-μm electroluminescence from the Au/nanometer (SiO2:Er/Si/SiO2:Er)/n+-Si structure

Y. Chen, G. Z. Ran, L. Dai, B. R. Zhang, G. G. Qin, Z. C. Ma, and W. H. Zong

Appl. Phys. Lett. 80, 2496 (2002); http://dx.doi.org/10.1063/1.1467623 (3 pages) | Cited 5 times

Online Publication Date: 2 April 2002

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The (SiO2:Er/Si/SiO2:Er) nanometer sandwich structure, in which the thickness of the Si layer between the two SiO2:Er barriers was varied from 1.0 to 4.0 nm with an interval of 0.2 nm, was deposited on both n+-Si and p-Si substrates using the magnetron sputtering technique. Electroluminescence (EL) from the Au/(SiO2:Er/Si/SiO2:Er) nanometer sandwich /n+-Si diodes under reverse biases has been observed. The EL spectrum of each diode can be fitted by three Gaussian bands with peak energies of 0.757 eV (1.64 μm), 0.806 eV (1.54 μm), and 0.860 eV (1.44 μm), and full widths at half maximum of 0.052 eV, 0.045 eV, and 0.055 eV, respectively. The marked effect of the nanometer Si layer with suitable thickness on enhancing the EL from the Er3+ in the SiO2 layers has been demonstrated. Among the diodes with Si layers having various thicknesses, the intensities of the 1.64-, 1.54-, and 1.44-μm bands of the diode with a 1.6-nm Si layer attain maxima which are 22, 8, and 7 times larger than those of the control diode without any Si layer, respectively. © 2002 American Institute of Physics.
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85.60.Jb Light-emitting devices
78.67.-n Optical properties of low-dimensional, mesoscopic, and nanoscale materials and structures
78.60.Fi Electroluminescence
68.65.Ac Multilayers

Interface-controlled gate of GaAs metal–semiconductor field-effect transistor

Min-Gu Kang, Hyung-Ho Park, and Haecheon Kim

Appl. Phys. Lett. 80, 2499 (2002); http://dx.doi.org/10.1063/1.1467975 (3 pages) | Cited 4 times

Online Publication Date: 2 April 2002

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A two-step passivation using sulfidation and hydrogenation has been reported to improve the gate leakage current and breakdown voltage of the GaAs metal–semiconductor field-effect transistor (MESFET). The combination of S passivation and interfacial hydrogenation was applied to the gate line in the MESFET; leakage current was reduced over an order and breakdown voltage was improved to a maximum level of 14 V from 10 V. It was revealed that the improvement of device properties after this two-step treatment resulted from the suppression of defective states such as oxides and excess As at the interface of the gate junction. The evolution of their bonding states through the treatment was found to have a close relationship with the device parameters. © 2002 American Institute of Physics.
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85.30.Tv Field effect devices
81.65.Rv Passivation
73.20.Hb Impurity and defect levels; energy states of adsorbed species

Memory effects related to deep levels in metal–oxide–semiconductor structure with nanocrystalline Si

Young Hae Kwon, C. J. Park, W. C. Lee, D. J. Fu, Y. Shon, T. W. Kang, C. Y. Hong, H. Y. Cho, and Kang L. Wang

Appl. Phys. Lett. 80, 2502 (2002); http://dx.doi.org/10.1063/1.1467617 (3 pages) | Cited 27 times

Online Publication Date: 2 April 2002

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Nanocrystalline(nc)-Si was grown on SiO2 by rapid thermal chemical vapor deposition. The tunneling oxide layer of a thickness of 4 nm was formed on p-type Si(100) by rapid thermal oxidation at 1050 °C for 30 s. Metal–oxide–semiconductor (MOS) structures were fabricated and capacitance–voltage characterization was carried out to study the memory effects of the nc-Si embedded in the MOS structure. We found the memory effect to be dominantly related to hydrogen-related traps, in addition to being influenced by the three-dimensional quantum confinement and Coulomb charge effects. Deep level transient spectroscopy reveal that the activation energies of the hydrogen-related traps are Ev+0.29 eV (H1) and Ev+0.42 eV (H2), and the capture cross sections are 4.70×10−16 cm2 and 1.44×10−15 cm2, respectively. The presence of Si�H and Si�H2 bonds was confirmed by Fourier transform infrared spectroscopy. © 2002 American Institute of Physics.
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73.40.Qv Metal-insulator-semiconductor structures (including semiconductor-to-insulator)
73.63.Bd Nanocrystalline materials
73.20.Hb Impurity and defect levels; energy states of adsorbed species
71.55.Cn Elemental semiconductors
81.65.Mq Oxidation
78.67.Bf Nanocrystals, nanoparticles, and nanoclusters
78.30.Am Elemental semiconductors and insulators

Influence of the hole population on the transient reflectivity signal of annealed low-temperature-grown GaAs

V. Ortiz, J. Nagle, and A. Alexandrou

Appl. Phys. Lett. 80, 2505 (2002); http://dx.doi.org/10.1063/1.1463209 (3 pages) | Cited 7 times

Online Publication Date: 2 April 2002

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We study the influence of the carrier dynamics on the transient reflectivity of low-temperature-grown GaAs samples. We report a precise modeling of the recorded reflectivity data, which exhibit multiexponential decays and changes in sign, using a standard point defect model and taking into account the effects of the band filling, band gap renormalization, and trap absorption. We show that the valence-band hole population plays an important role in the behavior of the signals, and that it must be taken into account in order to optimize low-temperature-grown GaAs-based devices. © 2002 American Institute of Physics.
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78.66.Fd III-V semiconductors
78.47.-p Spectroscopy of solid state dynamics
71.55.Eq III-V semiconductors
78.30.Fs III-V and II-VI semiconductors
61.72.Cc Kinetics of defect formation and annealing
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