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11 Feb 2002

Volume 80, Issue 6, pp. 905-1104

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Rectification and shift currents in GaAs

D. Côté, N. Laman, and H. M. van Driel

Appl. Phys. Lett. 80, 905 (2002); http://dx.doi.org/10.1063/1.1436530 (3 pages) | Cited 25 times

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We observe second-order rectification and shift currents in GaAs at 295 K using 150 fs pulses at 1.55 and 0.775 μm, respectively. For the same low pump intensity, 100 MW cm−2, the shift current density is 570 times larger than the rectification current density. At high intensity, the shift current is strongly affected by carrier screening and dephasing and is in phase quadrature with the rectification current. A maximum shift current density of 60 kA cm−2 is inferred for a pump intensity of 500 MW cm−2. © 2002 American Institute of Physics.
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42.65.-k Nonlinear optics
73.40.Ei Rectification
72.80.Ey III-V and II-VI semiconductors
81.05.Ea III-V semiconductors

Sharp asymmetric line shapes in side-coupled waveguide-cavity systems

Shanhui Fan

Appl. Phys. Lett. 80, 908 (2002); http://dx.doi.org/10.1063/1.1448174 (3 pages) | Cited 111 times

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We show that, for an optical microcavity side coupled with a waveguide, sharp, and asymmetric line shapes can be created in the response function by placing two partially reflecting elements into the waveguides. In such a system, the transmission coefficient varies from 0% to 100% in a frequency range narrower than the full width of the resonance itself. We numerically demonstrate this effect by simulating the propagation of electromagnetic waves in a photonic crystal. © 2002 American Institute of Physics.
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42.79.Gn Optical waveguides and couplers
42.82.Et Waveguides, couplers, and arrays
42.79.Hp Optical processors, correlators, and modulators
42.65.Pc Optical bistability, multistability, and switching, including local field effects

Comparison of radiative properties of InAs quantum dots and GaInNAs quantum wells emitting around 1.3 μm

A. Markus, A. Fiore, J. D. Ganière, U. Oesterle, J. X. Chen, B. Deveaud, M. Ilegems, and H. Riechert

Appl. Phys. Lett. 80, 911 (2002); http://dx.doi.org/10.1063/1.1447595 (3 pages) | Cited 34 times

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The emission properties of self-assembled InAs quantum dots (QDs) and lattice-matched GaInNAs quantum wells (QWs) emitting around 1.3 μm were investigated by temperature-dependent and time-resolved photoluminescence (PL). The QDs have much higher PL efficiency at low excitation, but saturate faster as the excitation is increased, due to the lower density of states. Lifetime measurements show that nonradiative recombination plays a more important role in the GaInNAs QW than in QDs. © 2002 American Institute of Physics.
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78.55.Cr III-V semiconductors
78.67.De Quantum wells
78.67.Hc Quantum dots
78.47.-p Spectroscopy of solid state dynamics
73.21.Fg Quantum wells
81.07.St Quantum wells
73.21.La Quantum dots
81.07.Ta Quantum dots
81.05.Ea III-V semiconductors

Quantitative comparison of trimethylindium sources and assessment of their suitability for low threshold 980 nm InGaAs/GaAs lasers grown by chemical beam epitaxy

J. O. Maclean, T. Martin, M. R. Houlton, P. D. J. Calcott, S. G. Ayling, K. P. Hilton, S. A. Rushworth, and L. M. Smith

Appl. Phys. Lett. 80, 914 (2002); http://dx.doi.org/10.1063/1.1435806 (3 pages) | Cited 2 times

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Metalorganic compounds used as precursors for epitaxial growth by metalorganic vapor phase epitaxy (MOVPE) and chemical beam epitaxy (CBE), may be contaminated with oxygen-containing impurities. These impurities are a particular problem in the precursor purification process when they, or their adducts, are of similar volatility to the precursor. We report that improvements in precursor purity, in this case trimethylindium (TMIn), may be quantitatively assessed through growth at low temperatures by CBE and subsequent two-stage testing. Indium-containing III–V semiconductor test structures were characterized first using secondary ion mass spectrometry (SIMS) and second by photoluminescence (PL) lifetime measurements which sensitively probe the presence of nonradiative centers. A factor of 4 improvement in PL lifetime was found for Epipure™ TMIn as compared with conventional adduct-purified TMIn. The Epipure™ grade of TMIn was used for 980 nm lasers. State-of-the-art threshold currents (162 A cm−2) and low internal optical cavity losses (3.9 cm−1) were obtained using CBE growth at the very low temperature of 540 °C. © 2002 American Institute of Physics.
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81.15.Hi Molecular, atomic, ion, and chemical beam epitaxy
42.60.By Design of specific laser systems
42.55.Px Semiconductor lasers; laser diodes
81.05.Ea III-V semiconductors
68.55.-a Thin film structure and morphology
78.55.Cr III-V semiconductors
78.66.Fd III-V semiconductors
85.35.Be Quantum well devices (quantum dots, quantum wires, etc.)

Sol–gel glass distributed feedback waveguide laser

Xiao-lei Zhu and Dennis Lo

Appl. Phys. Lett. 80, 917 (2002); http://dx.doi.org/10.1063/1.1448386 (3 pages) | Cited 21 times

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Titania–silica glass films doped with Rhodamine 6G dye were fabricated using the low-temperature sol–gel technique. Films of thickness varying from 0.7 to 1.1 μm and of refractive index from 1.61 to 1.54 were obtained by controlling the revolution speed of spin coating and by changing the ratio of the sol–gel precursors. Tunable laser action was observed for the sol–gel glass films on glass or quartz substrates when a dynamic gain modulation was optically generated. Lasing with multiple guiding modes was achieved at a film thickness of 1.1 μm. The effect of optical confinement was studied by varying the difference of refractive indices between the sol–gel film and the substrate. © 2002 American Institute of Physics.
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42.55.Mv Dye lasers
42.60.Fc Modulation, tuning, and mode locking
42.55.Rz Doped-insulator lasers and other solid state lasers

Monte Carlo simulation of electron dynamics in superlattice quantum cascade lasers

F. Compagnone, A. Di Carlo, and P. Lugli

Appl. Phys. Lett. 80, 920 (2002); http://dx.doi.org/10.1063/1.1448664 (3 pages) | Cited 21 times

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A theoretical investigation of electron dynamics in superlattice InGaAs/AlInAs quantum cascade lasers (QCLs) is presented, based on a Monte Carlo simulation that includes both electron–electron and electron–phonon scattering. Nonequilibrium phonons and phonon quantization effects have been explicitly considered. Calculated luminescence and gain spectra are presented. Our analysis provides a clear physical insight into the QCL operational mode. © 2002 American Institute of Physics.
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42.55.Px Semiconductor lasers; laser diodes
85.35.Be Quantum well devices (quantum dots, quantum wires, etc.)
42.60.Da Resonators, cavities, amplifiers, arrays, and rings
85.30.De Semiconductor-device characterization, design, and modeling
42.60.By Design of specific laser systems
42.55.Ah General laser theory
71.38.-k Polarons and electron-phonon interactions
78.55.Cr III-V semiconductors
78.66.Fd III-V semiconductors

Polarization properties of ultrafast white-light continuum generated in condensed media

Katsumi Midorikawa, Hiroyuki Kawano, Akira Suda, Chihiro Nagura, and Minoru Obara

Appl. Phys. Lett. 80, 923 (2002); http://dx.doi.org/10.1063/1.1448146 (3 pages) | Cited 13 times

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Polarization properties of a white-light continuum generated by 392 nm femtosecond laser pulses in transparent condensed media is investigated. Self-induced polarization change of the generated white-light continuum is observed in an isotropic material with a cubic crystal structure such as CaF2 and LiF. The experimental observation is explained by considering self-induced birefringence. © 2002 American Institute of Physics.
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42.70.Mp Nonlinear optical crystals
42.65.-k Nonlinear optics
78.20.Fm Birefringence
78.20.Ci Optical constants (including refractive index, complex dielectric constant, absorption, reflection and transmission coefficients, emissivity)

Influence of electron injection on performance of GaN photodetectors

Leonid Chernyak, Alfons Schulte, Andrei Osinsky, John Graff, and E. Fred Schubert

Appl. Phys. Lett. 80, 926 (2002); http://dx.doi.org/10.1063/1.1448382 (3 pages) | Cited 4 times

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It is demonstrated that short-time (up to 1200 s) electron injection into the p-region of GaN p–n junction, as a result of forward bias application, leads to a long-term multifold enhancement of the device peak responsivity as well as to a spectral broadening of the photoresponse. The effect is found to persist for several days and is related to an increased minority carrier diffusion length in the p region, due to an injected electron trapping on deep levels associated with Mg acceptors. © 2002 American Institute of Physics.
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85.60.Gz Photodetectors (including infrared and CCD detectors)
71.55.Eq III-V semiconductors

Spatially resolved derivative spectroscopy of vertical-cavity surface-emitting lasers using near-field scanning optical microscopy

W. C. Bradford, J. D. Beach, R. T. Collins, D. W. Kisker, and D. Galt

Appl. Phys. Lett. 80, 929 (2002); http://dx.doi.org/10.1063/1.1448861 (3 pages) | Cited 1 time

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A near-field scanning optical microscope was used in collection mode to generate spatially resolved maps of the first derivative with respect to operating current of power emission from vertical-cavity surface-emitting lasers (VCSELs). This technique is highly sensitive to the formation of new modes and can be used to identify mode cutoff points. An example of the usefulness of this technique is demonstrated as we estimate the index of refraction profile of the VCSEL under study at the single mode cutoff point. This profile is a primary feature of the waveguiding characteristics of such lasers. © 2002 American Institute of Physics.
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42.55.Px Semiconductor lasers; laser diodes
42.60.Da Resonators, cavities, amplifiers, arrays, and rings
42.60.By Design of specific laser systems
78.20.Ci Optical constants (including refractive index, complex dielectric constant, absorption, reflection and transmission coefficients, emissivity)
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Spatially resolved electron temperature measurements with a microfabricated retarding field analyzer

M. J. Sowa, M. G. Blain, R. L. Jarecki, and J. E. Stevens

Appl. Phys. Lett. 80, 932 (2002); http://dx.doi.org/10.1063/1.1448170 (3 pages)

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Electron temperature (Te) is an important parameter to quantify in the high-density plasmas commonly used in semiconductor manufacturing. Te is characteristic of the electron energy distribution which determines the plasma density and distribution of neutral and ionic species. Through application of theoretical considerations for the presheath and sheath, Te can be estimated from the ion energy distribution to a floating substrate. Utilizing microfabricated retarding field analyzers (RFAs) to measure the local ion energy distribution to a floating surface, spatially resolved Te measurements in an inductively coupled argon plasma have been made. Quantitative agreement between the RFA and Langmuir probe Te measurements was observed and the RFA Te measurements display the expected power, pressure, and spatial dependencies. © 2002 American Institute of Physics.
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52.70.Ds Electric and magnetic measurements
52.40.Kh Plasma sheaths
52.25.-b Plasma properties
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An x-ray rocking curve technique for the absolute characterization of epitaxial layers and single-crystal solids

M. Fatemi

Appl. Phys. Lett. 80, 935 (2002); http://dx.doi.org/10.1063/1.1447012 (3 pages) | Cited 8 times

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A rapid double-crystal x-ray diffractometer technique for the absolute measurement of lattice parameters in single crystals and epitaxial layers is introduced. The method is based on the principle that in a diffractometer aligned for rocking curve measurements within a given zone, the zero setting correction is the same for all crystal angles within the zone. The peak positions can thus be measured and corrected quickly, and the lattice parameters evaluated within each layer independently of others. The proof-of-principle tests are given for Si and InP, and the method is applied to a GaN film grown on an a-plane sapphire wafer. The method has unlimited accuracy depending only on the instrumental alignment and material quality. © 2002 American Institute of Physics.
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68.55.-a Thin film structure and morphology
61.05.cp X-ray diffraction

Amorphous layer formation at the TaC/Cu interface in the Si/TaC/Cu metallization system

Tomi Laurila, Kejun Zeng, Jorma K. Kivilahti, Jyrki Molarius, and Ilkka Suni

Appl. Phys. Lett. 80, 938 (2002); http://dx.doi.org/10.1063/1.1447601 (3 pages) | Cited 9 times

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An amorphous Ta(O,C)x layer was found to form at the TaC/Cu interface in the Si/TaC/Cu metallization system. The formation of the layer was induced by oxygen trapped in the as-deposited films, since on the basis of thermodynamic evaluation of the ternary Ta–C–O system, the dissociation of the TaC layer and the formation of the Ta2O5 and graphite can be expected to occur during subsequent annealings in this case. However, as observed experimentally, the formation of the amorphous Ta(O,C)x preceded the formation of the stable tantalum oxide. © 2002 American Institute of Physics.
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85.40.Ls Metallization, contacts, interconnects; device isolation
61.43.-j Disordered solids
61.72.Cc Kinetics of defect formation and annealing

Dependence of the excitonic transition energies and mosaicity on residual strain in ZnO thin films

H. C. Ong, A. X. E. Zhu, and G. T. Du

Appl. Phys. Lett. 80, 941 (2002); http://dx.doi.org/10.1063/1.1448660 (3 pages) | Cited 54 times

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The mosacity and optical properties of ZnO on (0001) Al2O3 grown by pulsed-laser deposition have been studied by x-ray diffraction and spectroscopic ellipsometry. Strong dependence has been found between the grain size and the residual strain along the c axis, ϵzz, as well as the film texture. In general, strain relieves and texture improves at larger grain size regardless of the growth conditions. The excitonic transition energies are also found to vary in the presence of strain field. It is observed that the transition energies increase with increasing strain and eventually they are resolved into two well-defined bands at the strain of 1.63%. By taking into account of the biaxial strain, the theoretical band structure of ZnO has been considered by solving the Luttinger–Kohn Hamiltonian. Reasonable agreement is found between the theory and experiment. © 2002 American Institute of Physics.
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71.35.Cc Intrinsic properties of excitons; optical absorption spectra
68.55.-a Thin film structure and morphology
78.66.Hf II-VI semiconductors
68.60.Bs Mechanical and acoustical properties
78.40.Fy Semiconductors
81.05.Dz II-VI semiconductors
81.15.Fg Pulsed laser ablation deposition
71.20.Nr Semiconductor compounds

In situ observation of nickel metal-induced lateral crystallization of amorphous silicon thin films

Mitsutoshi Miyasaka, Kenji Makihira, Tanemasa Asano, Efstathios Polychroniadis, and John Stoemenos

Appl. Phys. Lett. 80, 944 (2002); http://dx.doi.org/10.1063/1.1447014 (3 pages) | Cited 20 times

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The lateral crystallization of amorphous silicon thin films induced by nickel was studied in detail, performing in situ annealing experiments with a transmission electron microscope. The nickel-induced crystallization starts with the fast growth of thin needle-like crystallites of [110] orientation, which advance along the 〈111〉 directions within the film plane. The fast growth rate and the small probability of the crystallite exhibiting the [110] orientation result in large crystalline grains. These grains are, however, composed of many small misorientated subgrains. It is thought that this is because the needle-like crystallite does not grow continuously but grows by successive jumps. Our model is that after the nickel disilicide precipitate grows a thin crystalline slice epitaxially at the leading edge of the needle-like crystallite, the nickel moves to the new leading edge and forms the new nickel disilicide precipitates to maintain the needle-like crystalline growth. © 2002 American Institute of Physics.
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68.55.A- Nucleation and growth
61.43.Dq Amorphous semiconductors, metals, and alloys
68.35.Fx Diffusion; interface formation

Simple expression for vacancy concentrations at half ion range following MeV ion implantation of silicon

P. G. Coleman, C. P. Burrows, and A. P. Knights

Appl. Phys. Lett. 80, 947 (2002); http://dx.doi.org/10.1063/1.1448856 (3 pages) | Cited 16 times

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Mean concentrations CD of aggregated vacancy-type point-defect structures in float-zone Si implanted with H+, B+, Si+, O+, and Ge2+ ions at energies between 0.45 and 4.0 MeV have been measured as a function of ion dose ϕ at depths ∼ RP/2 (half projected ion range) by beam-based positron spectroscopy. By adjusting ϕ to ϕA using factors given by the code TRIM, one arrives at the universal expression CD = (2.79×1010) ϕA0.63; CD (cm−3) can be estimated to ±50% for MeV ions implanted for ϕA from 109×1013 cm−2, which corresponds to an upper limit dose approaching 1014 cm−2 for 2 MeV Si+ implantation. © 2002 American Institute of Physics.
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61.72.J- Point defects and defect clusters
61.72.uf Ge and Si
61.80.Jh Ion radiation effects
61.82.Fk Semiconductors
78.70.Bj Positron annihilation

Control of hole carrier density of polycrystalline Cu2O thin films by Si doping

S. Ishizuka, S. Kato, Y. Okamoto, and K. Akimoto

Appl. Phys. Lett. 80, 950 (2002); http://dx.doi.org/10.1063/1.1448398 (3 pages) | Cited 12 times

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The effects on the electrical properties of Si doping into Cu2O thin films deposited by reactive sputtering were studied. The hole density increased from 1×1015 to 1×1017 cm−3 with increasing Si content and the minimum resistivity obtained was 12 Ω cm. It was suggested that the electrically active acceptor with an activation energy of 0.19 eV was generated by Si doping. Infrared absorption measurements indicated the formation of silicate in Si-doped Cu2O. The mechanism for Si acting as an acceptor in Cu2O is discussed and modeled based on the silicate formation in Cu2O. © 2002 American Institute of Physics.
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73.61.Le Other inorganic semiconductors
78.30.Hv Other nonmetallic inorganics

Strain and crystallographic tilt in uncoalesced GaN layers grown by maskless pendeoepitaxy

S. Einfeldt, A. M. Roskowski, E. A. Preble, and R. F. Davis

Appl. Phys. Lett. 80, 953 (2002); http://dx.doi.org/10.1063/1.1448145 (3 pages) | Cited 21 times

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The strain in thin GaN layers grown by maskless pendeoepitaxy has been investigated using high-resolution x-ray diffraction and finite-element simulations. The crystallographic tilt of the free-hanging wings was determined to result from the strain relaxation of the seed stripes along [0001]. The impact of the dimensions of the pendeostructure and of the formation of crystal defects on the expected wing tilt is discussed. © 2002 American Institute of Physics.
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68.60.Bs Mechanical and acoustical properties
81.15.Kk Vapor phase epitaxy; growth from vapor phase
68.55.-a Thin film structure and morphology
81.15.Gh Chemical vapor deposition (including plasma-enhanced CVD, MOCVD, ALD, etc.)

Mechanical deformation of single-crystal ZnO

S. O. Kucheyev, J. E. Bradby, J. S. Williams, C. Jagadish, and M. V. Swain

Appl. Phys. Lett. 80, 956 (2002); http://dx.doi.org/10.1063/1.1448175 (3 pages) | Cited 108 times

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The deformation behavior of bulk ZnO single crystals is studied by a combination of spherical nanoindentation and atomic force microscopy. Results show that ZnO exhibits plastic deformation for relatively low loads (≳4–13 mN with an ∼4.2 μm radius spherical indenter). Interestingly, the elastic–plastic deformation transition threshold depends on the loading rate, with faster loading resulting, on average, in larger threshold values. Multiple discontinuities (so called “pop-in” events) in force–displacement curves are observed during indentation loading. No discontinuities are observed on unloading. Slip is identified as the major mode of plastic deformation in ZnO, and pop-in events are attributed to the initiation of slip. An analysis of partial load–unload data reveals values of the hardness and Young’s modulus of 5.0±0.1 and 111.2±4.7 GPa, respectively, for a plastic penetration depth of 300 nm. Physical processes determining deformation behavior of ZnO are discussed. © 2002 American Institute of Physics.
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62.20.F- Deformation and plasticity
81.40.Lm Deformation, plasticity, and creep
62.20.Qp Friction, tribology, and hardness
68.35.Gy Mechanical properties; surface strains
81.40.Np Fatigue, corrosion fatigue, embrittlement, cracking, fracture, and failure
62.20.M- Structural failure of materials
62.20.D- Elasticity
81.40.Jj Elasticity and anelasticity, stress-strain relations

Effect of adsorption on nanoindentation test

Fuqian Yang

Appl. Phys. Lett. 80, 959 (2002); http://dx.doi.org/10.1063/1.1448657 (3 pages) | Cited 8 times

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The contact stiffness widely used in nanoindentation test is based on the Hertzian contact theory for zero-interfacial friction (slip boundary condition), in which the effect of adhesion energy is ignored. However, in the real situation, the adhesion energy may not be negligible when the contact is adhesive. A solution of the contact stiffness is derived by using adhesive contact theory for both frictionless condition (the famous Johnson–Kendall–Roberts theory) and the sticky condition. The results show that the nominal contact stiffness depends on the adhesion energy and indenter size as well as the load applied to indenter. For a large size of indenter and small load, the adhesion energy controls the contact process; while for a large load, the elastic deformation dominates, in which the nominal contact stiffness approaches the result based on the Hertzian contact theory. © 2002 American Institute of Physics.
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46.55.+d Tribology and mechanical contacts
68.35.Np Adhesion
68.35.Gy Mechanical properties; surface strains
81.70.-q Methods of materials testing and analysis
62.20.D- Elasticity
81.40.Jj Elasticity and anelasticity, stress-strain relations

Photoluminescence dependence on heterointerface for metalorganic chemical vapor deposition grown GaInNAs/GaAs quantum wells

M. Kawaguchi, T. Miyamoto, E. Gouardes, T. Kondo, F. Koyama, and K. Iga

Appl. Phys. Lett. 80, 962 (2002); http://dx.doi.org/10.1063/1.1448656 (3 pages) | Cited 5 times

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We investigate the effect of the sequence of gas flows at heterointerfaces on optical quality of GaInNAs/GaAs quantum wells grown by metalorganic chemical vapor deposition (MOCVD). We point out that the degradation mechanism of photoluminescence of GaInNAs grown by MOCVD method is categorized in two types. One is the formation of a GaNAs layer at the heterointerface which causes both increase of emission wavelength and degradation of crystal quality. The other is generation of nonradiative centers induced by incorporation of nitrogen (N). The insertion of a GaInAs layer to the GaInNAs/GaAs heterointerface is proposed to overcome these degradation mechanisms. A GaInAs intermediate layer is effective to suppress the GaNAs formation and to reduce the total GaInNAs thickness. © 2002 American Institute of Physics.
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78.67.De Quantum wells
78.55.Cr III-V semiconductors
81.07.St Quantum wells
73.21.Fg Quantum wells
68.65.Fg Quantum wells
81.15.Gh Chemical vapor deposition (including plasma-enhanced CVD, MOCVD, ALD, etc.)

Different behavior of photoluminescence anisotropy in porous silicon layers made by polarized-light-assisted electrochemical etching

Hideki Koyama

Appl. Phys. Lett. 80, 965 (2002); http://dx.doi.org/10.1063/1.1449538 (3 pages) | Cited 3 times

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Luminescent porous silicon (PSi) layers have been made on n-type Si wafers by anodization in a HF solution under illumination with linearly polarized light. It is observed that the photoluminescence from samples anodized at a current density of 30 mA/cm2 and slightly oxidized electrochemically for passivation exhibits a significant anisotropy in polarization memory (PM): the degree of PM becomes maximum when the vector electric field (Eexc) of excitation laser light is parallel to that (Eetch) of the light used during anodization, and minimum when Eexc is perpendicular to Eetch. These maxima and minima are in totally different directions from those reported previously. In addition, the anisotropy is found to be weak at low anodization current density of 2.3 mA/cm2. These experimental results are discussed based on the electrochemical, rather than photochemical, thinning of Si-nanocrystal assemblies in PSi layers. © 2002 American Institute of Physics.
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78.55.Mb Porous materials
78.55.Ap Elemental semiconductors
81.65.Cf Surface cleaning, etching, patterning
78.66.Db Elemental semiconductors and insulators
81.05.Cy Elemental semiconductors
81.05.Rm Porous materials; granular materials
81.65.Rv Passivation
82.50.-m Photochemistry
82.45.Jn Surface structure, reactivity and catalysis

Strong band edge luminescence from InN films grown on Si substrates by electron cyclotron resonance-assisted molecular beam epitaxy

Tokuo Yodo, Hiroaki Yona, Hironori Ando, Daiki Nosei, and Yoshiyuki Harada

Appl. Phys. Lett. 80, 968 (2002); http://dx.doi.org/10.1063/1.1450255 (3 pages) | Cited 36 times

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We observed strong band edge luminescence at 8.5–200 K from 200–880 nm thick InN films grown on 10 nm thick InN buffer layers on Si(001) and Si(111) substrates by electron cyclotron resonance-assisted molecular beam epitaxy. The InN film on the Si(001) substrate exhibited strong band edge photoluminescence (PL) emission at 1.814 eV at 8.5 K, tentatively assigned as donor to acceptor pair [DAP (α-InN)] emission from wurtzite-InN (α-InN) crystal grains, while those on Si(111) showed other stronger band edge PL emissions at 1.880, 2.081 and 2.156 eV, tentatively assigned as donor bound exciton [D0X(α-InN)] from α-InN grains, DAP (β-InN) and D0X (β-InN) emissions from zinc blende-InN (β-InN) grains, respectively. © 2002 American Institute of Physics.
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78.66.Fd III-V semiconductors
78.55.Cr III-V semiconductors
71.35.Cc Intrinsic properties of excitons; optical absorption spectra
81.05.Ea III-V semiconductors
81.15.Hi Molecular, atomic, ion, and chemical beam epitaxy

Femtosecond all-optical polarization switching based on the virtual excitation of spin-polarized excitons in quantum wells

Eric J. Gansen, K. Jarasiunas, and Arthur L. Smirl

Appl. Phys. Lett. 80, 971 (2002); http://dx.doi.org/10.1063/1.1447596 (3 pages) | Cited 16 times

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An optically addressed nonlinear polarization switch based on the near-resonant excitation of a spin-polarized population of virtual excitons is demonstrated in a multiple quantum well. Pulse-width-limited switching (∼400 fs full width at half maximum) and high-contrast performance (194:1) are achieved in a thin (40 well) sample at 100 K. Differential absorption measurements identify the dominant switching mechanisms. © 2002 American Institute of Physics.
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42.65.Pc Optical bistability, multistability, and switching, including local field effects
42.65.Re Ultrafast processes; optical pulse generation and pulse compression
71.35.-y Excitons and related phenomena
78.67.De Quantum wells
85.35.Be Quantum well devices (quantum dots, quantum wires, etc.)
73.21.Fg Quantum wells

Improved thermal stability of wet-oxidized AlAs

H. Q. Jia, H. Chen, W. C. Wang, W. X. Wang, W. Li, Q. Huang, Junming Zhou, and Q. K. Xue

Appl. Phys. Lett. 80, 974 (2002); http://dx.doi.org/10.1063/1.1448166 (3 pages) | Cited 8 times

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Lateral thermal wet oxidization of the AlAs layer in a GaAs/AlAs/GaAs sandwiched structure is studied by Raman spectroscopy and Nomarski microscopy. A significant improvement in thermal stability of the oxidized AlAs layer has been achieved by optimizing the oxidation conditions, which can be used to fabricate reliable devices. We show that the thermal stability is strongly related to the removal of volatile products, such as As and As2O3, as evidenced by the Raman spectroscopy measurement. © 2002 American Institute of Physics.
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81.05.Ea III-V semiconductors
81.65.Mq Oxidation
78.30.Fs III-V and II-VI semiconductors
78.66.Fd III-V semiconductors

Two mechanisms of blueshift of edge emission in InGaN-based epilayers and multiple quantum wells

E. Kuokstis, J. W. Yang, G. Simin, M. Asif Khan, R. Gaska, and M. S. Shur

Appl. Phys. Lett. 80, 977 (2002); http://dx.doi.org/10.1063/1.1433164 (3 pages) | Cited 55 times

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We present the results of a comparative photoluminescence (PL) study of GaN and InGaN-based epilayers, and InGaN/GaN multiple quantum wells (MQWs). Room-temperature PL spectra were measured for a very broad range of optical excitation from 10 mW/cm2 up to 1 MW/cm2. In contrast to GaN epilayers, all In-containing samples exhibited an excitation-induced blueshift of the peak emission. In addition, the blueshift of the emission in the InGaN epilayers with the same composition as the quantum well was significantly smaller. The comparison of the blueshift in the “bulk” InGaN and in the MQWs allowed us to separate two different mechanisms responsible for this effect: (i) filling of the localized states in In-rich areas and (ii) screening of the polarization electric field in strained MQW structures. © 2002 American Institute of Physics.
Show PACS
78.67.De Quantum wells
78.66.Fd III-V semiconductors
78.55.Cr III-V semiconductors
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