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23 Mar 1998

Volume 72, Issue 12, pp. 1409-1518

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Optical properties of low band gap GaAs(1−x)Nx layers: Influence of post-growth treatments

E. V. K. Rao, A. Ougazzaden, Y. Le Bellego, and M. Juhel

Appl. Phys. Lett. 72, 1409 (1998); http://dx.doi.org/10.1063/1.120579 (3 pages) | Cited 94 times

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A detailed study on the optical quality of atmospheric pressure metalorganic vapor phase epitaxy grown GaAs(1−x)Nx epilayers (on GaAs substrates) in which the N incorporation is accomplished using dimethylhydrazine precursor is reported. We show here that the poor optical quality of these as-grown layers can be significantly improved by carefully planned post-growth heat treatments. Optical data are presented to demonstrate unambiguously that such treatments affect in no way the physical properties of these metastable layers (no phase separation) and that the improvement of their optical quality is closely connected to the incorporation behavior of N in this growth method. © 1998 American Institute of Physics.
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78.66.Fd III-V semiconductors
78.55.Cr III-V semiconductors
81.05.Ea III-V semiconductors
81.15.Kk Vapor phase epitaxy; growth from vapor phase
81.40.Gh Other heat and thermomechanical treatments
81.40.Tv Optical and dielectric properties related to treatment conditions

Kinetic energy influence of hyperthermal dual ion beams on bonding and optical properties of carbon nitride films

N. Tsubouchi, Y. Horino, B. Enders, A. Chayahara, A. Kinomura, and K. Fujii

Appl. Phys. Lett. 72, 1412 (1998); http://dx.doi.org/10.1063/1.120580 (3 pages) | Cited 7 times

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Carbon nitride films were produced by simultaneous irradiation of well-defined hyperthermal (50–400 eV), isotopically mass-separated 12C2− and 14N+ ions with various kinetic energy combinations. It was found that the intensity of CN-triple bonds normalized by the amount of nitrogen atoms in the films and the complex refraction index (n,k) are correlated with the energy combination of 12C2− and 14N+ ions. © 1998 American Institute of Physics.
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81.05.Je Ceramics and refractories (including borides, carbides, hydrides, nitrides, oxides, and silicides)
68.55.-a Thin film structure and morphology
81.15.-z Methods of deposition of films and coatings; film growth and epitaxy
61.80.Jh Ion radiation effects
78.20.Ci Optical constants (including refractive index, complex dielectric constant, absorption, reflection and transmission coefficients, emissivity)
78.66.Nk Insulators

Photostimulable luminescence and imaging in vapor-deposited BaFCl:Eu thin film phosphors

P. F. Carcia, R. S. McLean, M. K. Crawford, and B. D. Jones

Appl. Phys. Lett. 72, 1415 (1998); http://dx.doi.org/10.1063/1.120581 (3 pages) | Cited 2 times

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Thin films of BaFCl:Eu with photostimulable luminescence (PSL) were grown by vapor deposition. For substrate temperatures at or below 350 °C, films were optically transparent and exhibited higher resolution in x-ray imaging than a commercial, particulate PSL phosphor screen, when luminescence was stimulated by scanning with a focused HeNe laser. Although post annealing films in a hydrogen atmosphere at 600–900 °C increased their PSL signal, which was relatively weak in as-deposited films, annealing reduced imaging resolution, apparently because of an increase in optical scattering of the focused laser. The implications of hydrogen annealing for the PSL mechanism are also discussed. © 1998 American Institute of Physics.
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78.66.Nk Insulators
78.55.Hx Other solid inorganic materials
07.85.-m X- and γ-ray instruments
81.40.Gh Other heat and thermomechanical treatments
81.40.Tv Optical and dielectric properties related to treatment conditions

Gain characteristics of InGaN/GaN quantum well diode lasers

Y.-K. Song, M. Kuball, A. V. Nurmikko, G. E. Bulman, K. Doverspike, S. T. Sheppard, T. W. Weeks, M. Leonard, H. S. Kong, H. Dieringer, and J. Edmond

Appl. Phys. Lett. 72, 1418 (1998); http://dx.doi.org/10.1063/1.120607 (3 pages) | Cited 37 times

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We have investigated spectroscopically the gain characteristics of InGaN quantum well (QW) diode lasers. While the transparency condition can be reached at a moderate current density, the filling of localized band-edge states is a prerequisite for achieving lasing in this profoundly nonrandom alloy. © 1998 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
73.21.-b Electron states and collective excitations in multilayers, quantum wells, mesoscopic, and nanoscale systems

Optical study of GaAs/AlAs pillar microcavities with elliptical cross section

B. Gayral, J. M. Gérard, B. Legrand, E. Costard, and V. Thierry-Mieg

Appl. Phys. Lett. 72, 1421 (1998); http://dx.doi.org/10.1063/1.120582 (3 pages) | Cited 36 times

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GaAs/AlAs pillar microcavities with elliptical cross section have been fabricated by molecular beam epitaxy, electron-beam lithography, and reactive ion etching. We study their lowest energy confined photonic modes by photoluminescence, using a quantum box array placed inside the cavity as an internal broadband light source. Such an anisotropic cross section allows to split the twofold polarization degenerate fundamental mode of circular micropillars into a pair of orthogonal linearly polarized modes. Their energy splitting, which is well accounted for by a simple perturbative model, is studied experimentally and theoretically as a function of the eccentricity and average radius of the pillars. Splittings as large as 15 meV are observed, which is very encouraging for applications ranging from the improvement of the polarization locking in vertical cavity lasers to the fabrication of light emitting diodes with a better control of the spontaneous emission. © 1998 American Institute of Physics.
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78.66.Fd III-V semiconductors
81.05.Ea III-V semiconductors
81.65.Cf Surface cleaning, etching, patterning
81.07.-b Nanoscale materials and structures: fabrication and characterization
78.55.Cr III-V semiconductors
73.21.-b Electron states and collective excitations in multilayers, quantum wells, mesoscopic, and nanoscale systems
85.40.Hp Lithography, masks and pattern transfer
52.77.Bn Etching and cleaning
52.77.Dq Plasma-based ion implantation and deposition

Sensitivity of optimization of mid-infrared InAs/InGaSb laser active regions to temperature and composition variations

Michael E. Flatté, C. H. Grein, and H. Ehrenreich

Appl. Phys. Lett. 72, 1424 (1998); http://dx.doi.org/10.1063/1.120583 (3 pages) | Cited 7 times

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We calculate the temperature dependence of the threshold current density Jth in optimized (minimal Jth) and unoptimized InAs/InGaSb superlattices. We find that the threshold current density of the unoptimized superlattice is well described by Jth∝eT/T0, with T0 ∼ 32 K from 25 to 275 K. This is the first microscopic calculation for these superlattices which indicates that Jth is well described by an empirical exponential form. In contrast, the threshold current density of the optimized superlattice is not well parametrized by a characteristic temperature T0. This superlattice is only optimized between 250 and 350 K, due to the sharp structure of the intersubband absorption spectrum. We also consider the effect on Jth of uncertainties in layer thicknesses. © 1998 American Institute of Physics.
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42.55.Px Semiconductor lasers; laser diodes
42.60.By Design of specific laser systems
85.35.Be Quantum well devices (quantum dots, quantum wires, etc.)
85.30.De Semiconductor-device characterization, design, and modeling

Sensitivity-enhanced reflection Z-scan by oblique incidence of a polarized beam

M. Martinelli, S. Bian, J. R. Leite, and R. J. Horowicz

Appl. Phys. Lett. 72, 1427 (1998); http://dx.doi.org/10.1063/1.120584 (3 pages) | Cited 11 times

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We demonstrate a new experimental method which allows the measurement of the nonlinear optic index in absorptive media with great sensitivity. In this technique the reflection from a polarized Gaussian laser beam close to the Brewster angle is measured. A sensitivity enhancement factor of 30 with respect to other techniques is observed for an optical crystal, and higher values are possible to be obtained. © 1998 American Institute of Physics.
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42.70.Mp Nonlinear optical crystals
07.60.Hv Refractometers and reflectometers

Continuous-wave and high-power pulsed operation of index-coupled distributed feedback quantum cascade laser at λ ≈ 8.5 μm

Claire Gmachl, Federico Capasso, Jérôme Faist, Albert L. Hutchinson, Alessandro Tredicucci, Deborah L. Sivco, James N. Baillargeon, S. N. George Chu, and Alfred Y. Cho

Appl. Phys. Lett. 72, 1430 (1998); http://dx.doi.org/10.1063/1.120585 (3 pages) | Cited 58 times

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High performance index-coupled quantum cascade distributed feedback (QC-DFB) lasers operating at λ ≈ 8.5 μm are reported. Reliable dynamic single-mode emission with a side mode suppression ratio ≥ 30 dB is obtained. The continuous single-mode tuning range is 140 nm. In pulsed operation a record high peak output power of 60 mW at 300 K is achieved. We further report on the first continuous-wave QC-DFB lasers. These devices display an output power of 10 mW at 120 K.
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42.55.Px Semiconductor lasers; laser diodes
42.60.By Design of specific laser systems
85.35.Be Quantum well devices (quantum dots, quantum wires, etc.)
42.60.Fc Modulation, tuning, and mode locking
42.60.Jf Beam characteristics: profile, intensity, and power; spatial pattern formation
42.60.Pk Continuous operation

High-gain excitonic lasing from a single InAs monolayer in bulk GaAs

A. R. Goñi, M. Stroh, C. Thomsen, F. Heinrichsdorff, V. Türck, A. Krost, and D. Bimberg

Appl. Phys. Lett. 72, 1433 (1998); http://dx.doi.org/10.1063/1.120586 (3 pages) | Cited 21 times

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We report the observation of highly efficient laser emission from a single InAs layer with an effective thickness of 1.5 monolayers (ML) embedded in bulklike GaAs. Lasing action is obtained at the wavelength of the InAs thin-layer luminescence (870 nm) by cw optical pumping with a threshold power density of 0.9(3) kW/cm2 at 10 K. Gain measurements yield a very high material gain of 1.0(5)×104 cm−1 for the InAs layer when pumped with ∼ 10 kW/cm2 at low temperatures. The 0 dimensional character of the emission as determined from cathodoluminescence and the absence of band-gap renormalization with increasing pump level speak for an excitonic mechanism of population inversion. © 1998 American Institute of Physics.
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42.55.Px Semiconductor lasers; laser diodes
78.60.Hk Cathodoluminescence, ionoluminescence
71.35.Cc Intrinsic properties of excitons; optical absorption spectra
78.66.Fd III-V semiconductors

High power mid infrared operation of the atomic xenon laser

J. J. Wendland, R. J. Morley, H. J. Baker, and D. R. Hall

Appl. Phys. Lett. 72, 1436 (1998); http://dx.doi.org/10.1063/1.120587 (3 pages) | Cited 1 time

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We report high power cw operation of a slab waveguide atomic xenon laser in a spectral region of low atmospheric absorption. Using transverse radio frequency discharge excitation at 49 MHz and a hybrid waveguide-unstable resonator, with a sharp band edge on the reflectivity versus wavelength curve of the laser mirrors, 50 mW was obtained on the 3.869 μm transition and 210 mW on the 3.895 μm line. © 1998 American Institute of Physics.
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42.55.Lt Gas lasers including excimer and metal-vapor lasers

Mechanisms of optical gain in cubic gallium nitrite

J. Holst, L. Eckey, A. Hoffmann, I. Broser, B. Schöttker, D. J. As, D. Schikora, and K. Lischka

Appl. Phys. Lett. 72, 1439 (1998); http://dx.doi.org/10.1063/1.120588 (3 pages) | Cited 30 times

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We report on the mechanisms of optical gain in cubic GaN. Intensity-dependent gain spectra allow a distinction of the processes involved in providing optical amplification. For moderate excitation levels, the biexciton decay is responsible for a gain structure at 3.265 eV. With increasing excitation densities, gain is observed on the high energy side of the cubic band gap due to band filling processes. For the highest pump intensities, the electron-hole plasma is the dominant gain process. Gain values up to 210 cm−1 were obtained, indicating the high potential of cubic GaN for device applications. The observed gain mechanisms are similar to those of hexagonal GaN. © 1998 American Institute of Physics.
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78.45.+h Stimulated emission
78.55.Cr III-V semiconductors
42.55.Px Semiconductor lasers; laser diodes
71.35.Ee Electron-hole drops and electron-hole plasma

Application of self-focusing of ps laser pulses for three-dimensional microstructuring of transparent materials

D. Ashkenasi, H. Varel, A. Rosenfeld, S. Henz, J. Herrmann, and E. E. B. Cambell

Appl. Phys. Lett. 72, 1442 (1998); http://dx.doi.org/10.1063/1.120606 (3 pages) | Cited 32 times

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Self-focusing of ps laser pulses (λ=790 nm) due to the nonlinear Kerr effect is shown to provide an easy and flexible method for producing bulk structures with dimensions on the order of 10 μm without damaging the entrance or exit surfaces of the material. The depth at which damage occurs can be controlled by adjusting either the pulse energy or pulse length. A study of the dependence of structure depth on the square root of the laser power for a given pulse length provides a straightforward method for determining the nonlinear index of refraction (Kerr coefficient), n2. © 1998 American Institute of Physics.
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42.65.Jx Beam trapping, self-focusing and defocusing; self-phase modulation
42.65.Re Ultrafast processes; optical pulse generation and pulse compression
78.47.-p Spectroscopy of solid state dynamics
81.65.-b Surface treatments
78.20.Ci Optical constants (including refractive index, complex dielectric constant, absorption, reflection and transmission coefficients, emissivity)
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A universal characterization of nonlinear self-oscillation and chaos in various particle-wave-wall interactions

Hae June Lee, Jae Koo Lee, Min Sup Hur, and Yi Yang

Appl. Phys. Lett. 72, 1445 (1998); http://dx.doi.org/10.1063/1.120589 (3 pages) | Cited 10 times

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The comprehensive parameter space of self-oscillation and its period-doubling route to chaos are shown for bounded beam-plasma systems. In this parametrization, it is helpful to use a potentially universal parameter in close analogy with free-electron-laser chaos. A common parameter, which is related to the velocity slippage and the ratio of bounce to oscillation frequencies, is shown to have similar significance for different physical systems. This single parameter replaces the dependences on many input parameters, thus suitable for a simplifying and diagnostic measure of nonlinear dynamical and chaotic phenomena for various systems of particle-wave interactions. The results of independent kinetic simulations verify those of nonlinear fluid simulations. © 1998 American Institute of Physics.
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52.35.Mw Nonlinear phenomena: waves, wave propagation, and other interactions (including parametric effects, mode coupling, ponderomotive effects, etc.)
52.25.Gj Fluctuation and chaos phenomena
52.40.Mj Particle beam interactions in plasmas
52.40.Hf Plasma-material interactions; boundary layer effects
52.38.Bv Rayleigh scattering; stimulated Brillouin and Raman scattering
05.45.-a Nonlinear dynamics and chaos
52.70.-m Plasma diagnostic techniques and instrumentation
52.65.-y Plasma simulation
52.25.Dg Plasma kinetic equations

Langmuir probe analysis of distributed electron cyclotron resonance silicon nitride deposition plasma

F. Delmotte, M. C. Hugon, B. Agius, A. M. Pointu, and S. Teodoru

Appl. Phys. Lett. 72, 1448 (1998); http://dx.doi.org/10.1063/1.120608 (3 pages) | Cited 3 times

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Single and double Langmuir probe analyses have been realized in the wafer region of an electron cyclotron resonance reactor in its distributed configuration. Results in nitrogen gas have shown unambiguously that two electron populations exist in this region: one with low temperature (about 1–2eV) and high density and the second with higher temperature (about 8 eV) and lower density. Measurements in silicon nitride deposition plasma (nitrogen and silane gases) have been successfully realized and have shown that these two populations are also present. Finally, we try to correlate the plasma parameters (electron temperatures and densities and ions’ energy) to the deposited film parameters (deposition rate and refractive index). © 1998 American Institute of Physics.
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52.70.Ds Electric and magnetic measurements
52.77.Bn Etching and cleaning
52.77.Dq Plasma-based ion implantation and deposition
81.05.Je Ceramics and refractories (including borides, carbides, hydrides, nitrides, oxides, and silicides)
78.66.Nk Insulators
52.25.-b Plasma properties
78.20.Ci Optical constants (including refractive index, complex dielectric constant, absorption, reflection and transmission coefficients, emissivity)
81.15.Gh Chemical vapor deposition (including plasma-enhanced CVD, MOCVD, ALD, etc.)
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Synthesis of high-temperature superconductive and colossal magnetoresistive surfaces on insulating particles

D. Kumar, James Fitz-Gerald, and Rajiv K. Singh

Appl. Phys. Lett. 72, 1451 (1998); http://dx.doi.org/10.1063/1.120590 (3 pages) | Cited 5 times

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The surfaces of insulating alumina particles have been coated with high-temperature superconducting YBa2Cu3O7−x and colossal magnetoresistive Pr0.65Ba0.05Ca0.3MnO3−x films. These coatings on particulate surfaces have been realized using a technique which is based on laser-assisted generation of a homogeneous flux of ablated materials in front of a fluidized bed of host particles. The coated particulates have been characterized using scanning electron microscopy, energy dispersive x-ray analysis, Auger electron spectroscopy, and superconducting quantum interference device magnetometer. © 1998 American Institute of Physics.
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81.05.Je Ceramics and refractories (including borides, carbides, hydrides, nitrides, oxides, and silicides)
81.65.-b Surface treatments
74.72.-h Cuprate superconductors
75.47.De Giant magnetoresistance
82.80.Pv Electron spectroscopy (X-ray photoelectron (XPS), Auger electron spectroscopy (AES), etc.)
79.20.Fv Electron impact: Auger emission

Control and imaging of ferroelectric domains over large areas with nanometer resolution in atomically smooth epitaxial Pb(Zr0.2Ti0.8)O3 thin films

T. Tybell, C. H. Ahn, and J.-M. Triscone

Appl. Phys. Lett. 72, 1454 (1998); http://dx.doi.org/10.1063/1.120591 (3 pages) | Cited 82 times

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We have investigated the possibility afforded by epitaxial ferroelectric oxide thin films to control and image locally the polarization field of ferroelectrics over large areas with submicron resolution, using the metallic tip of an atomic force microscope as a mobile top electrode and local probe of the ferroelectric properties. Atomically smooth films of Pb(Zr0.2Ti0.8)O3, showing a root-mean-square roughness of typically a few angstroms, could be uniformly polarized and imaged over areas as large as 2500 μm2 without introducing any topographic disorder. Regular arrays of 100 nm wide lines and circular domains with a diameter less than 100 nm were written in arbitrary areas of the uniformly polarized regions. © 1998 American Institute of Physics.
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77.84.Ek Niobates and tantalates
77.84.Cg PZT ceramics and other titanates
77.55.-g Dielectric thin films
77.80.Dj Domain structure; hysteresis
68.35.B- Structure of clean surfaces (and surface reconstruction)
77.22.Ej Polarization and depolarization

Enhanced thermodynamic stability of tetragonal-phase field in epitaxial Pb(Zr,Ti)O3 thin films under a two-dimensional compressive stress

S. Hoon Oh and Hyun M. Jang

Appl. Phys. Lett. 72, 1457 (1998); http://dx.doi.org/10.1063/1.120609 (3 pages) | Cited 37 times

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A two-dimensional thermodynamic model was developed to account for the observed difficulty in the fabrication of epitaxial Pb(Zr,Ti)O3 (PZT) thin films in which tetragonal and rhombohedral phases coexist. The thermodynamic formalism based on the Landau–Devonshire’s phenomenological theory predicts the enhanced thermodynamic stability of the tetragonal-phase field under a two-dimensional compressive stress. We have experimentally proved this prediction by fabricating an epitaxially oriented tetragonal PZT thin film on MgO substrate with the target composition corresponding to the bulk morphotropic phase boundary (MPB). © 1998 American Institute of Physics.
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77.84.Ek Niobates and tantalates
77.84.Cg PZT ceramics and other titanates
77.55.-g Dielectric thin films
77.80.-e Ferroelectricity and antiferroelectricity
68.60.Dv Thermal stability; thermal effects
81.05.Je Ceramics and refractories (including borides, carbides, hydrides, nitrides, oxides, and silicides)
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Gettering of iron by oxygen precipitates

H. Hieslmair, A. A. Istratov, S. A. McHugo, C. Flink, T. Heiser, and E. R. Weber

Appl. Phys. Lett. 72, 1460 (1998); http://dx.doi.org/10.1063/1.120592 (3 pages) | Cited 19 times

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In order to better understand and model internal gettering of iron in silicon, a quantitative investigation of iron precipitation in silicon containing different oxygen precipitate densities was performed. The number of iron precipitation sites was obtained from the iron precipitation kinetics using Ham’s Law. At low temperatures, the iron precipitate density corresponded to the oxygen precipitate density. A strong temperature dependence of the iron precipitate density was observed for the samples with larger oxygen precipitate densities. These data were used to simulate iron precipitation during a slow cool. From those simulations, optimal cooling rates were obtained for different silicon materials assuming various iron precipitation site densities in the epitaxial layer. © 1998 American Institute of Physics.
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61.72.Yx Interaction between different crystal defects; gettering effect
81.05.Cy Elemental semiconductors
81.65.Tx Gettering
64.75.-g Phase equilibria

Role of arsenic clusters in carrier recombination in low-temperature grown AlGaAs/GaAs multiple quantum wells

W. Feng, Y. Wang, J. Wang, W. K. Ge, Q. Huang, and J. M. Zhou

Appl. Phys. Lett. 72, 1463 (1998); http://dx.doi.org/10.1063/1.120593 (3 pages) | Cited 7 times

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The low-temperature grown AlGaAs/GaAs multiple quantum well structures were characterized by photoluminescence (PL) spectroscopy. The samples were grown at 270–400 °C and annealed at 500–900 °C. After anneal, photoluminescence quenching was observed for the samples grown at temperatures below 350 °C, and found to show a strong dependence on the growth and anneal temperatures. The luminescence intensity for the PL-quenched sample exhibits a power law dependence on the excitation level with an exponent close to 2, indicating a bimolecular recombination process in parallel with strong nonradiative recombination. The photoluminescence quenching upon anneal is attributed to the formation of arsenic clusters that serve as new nonradiative recombination channels. © 1998 American Institute of Physics.
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78.66.Fd III-V semiconductors
78.55.Cr III-V semiconductors
73.21.-b Electron states and collective excitations in multilayers, quantum wells, mesoscopic, and nanoscale systems
61.72.Cc Kinetics of defect formation and annealing

Strain relaxation of InGaAs/GaAs superlattices by wet oxidation of underlying AlAs layer

Jin Ho Seo and Kwang Seok Seo

Appl. Phys. Lett. 72, 1466 (1998); http://dx.doi.org/10.1063/1.120594 (3 pages) | Cited 10 times

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The effects of AlAs wet oxidation on overlayers were investigated using InGaAs/GaAs strained-layer superlattice structures grown on an AlAs layer. The superlattice partially relaxes towards its equilibrium spacing as the result of the oxidation of the underlying AlAs layer. Double-crystal x-ray diffraction measurements were used to determine the degree of strain relaxation. Larger relaxation is observed for the sample with a higher indium composition and a thicker AlAs layer. © 1998 American Institute of Physics.
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68.35.Gy Mechanical properties; surface strains
81.05.Ea III-V semiconductors
68.65.-k Low-dimensional, mesoscopic, nanoscale and other related systems: structure and nonelectronic properties
81.65.Mq Oxidation
68.35.Ct Interface structure and roughness

Room-temperature oxidation of a GaAs(001) surface induced by the interaction of hyperthermal atomic oxygen and studied by x-ray photoelectron spectroscopy and ion scattering spectroscopy

John T. Wolan, Charles K. Mount, and Gar B. Hoflund

Appl. Phys. Lett. 72, 1469 (1998); http://dx.doi.org/10.1063/1.120595 (3 pages) | Cited 11 times

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In this study a hyperthermal oxygen atom source has been used to form an oxide layer on an Ar+-sputtered GaAs(001) surface at room temperature, and this layer has been examined using x-ray photoelectron spectroscopy (XPS) and ion scattering spectroscopy (ISS). XPS data indicate that the Ga in the near-surface region is oxidized predominantly to Ga2O3 with a significant contribution from GaAsO4 while the As is oxidized predominantly to an AsOx species with significant contributions from As2O3 and GaAsO4 and/or As2O5. The oxide layer thickness is estimated to be about 25 Å, and the XPS Ga:As atom ratio increases from 1.1 to 1.6 during the oxidation. The ISS data indicate that the resulting oxide layer formed is more electrically insulating than a native oxide layer on this surface. © 1998 American Institute of Physics.
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81.05.Ea III-V semiconductors
81.65.Mq Oxidation
79.20.Rf Atomic, molecular, and ion beam impact and interactions with surfaces
82.80.Pv Electron spectroscopy (X-ray photoelectron (XPS), Auger electron spectroscopy (AES), etc.)
79.60.Bm Clean metal, semiconductor, and insulator surfaces

Characterization of GaAs surfaces treated with phosphine gas photodecomposed by an ArF excimer laser

Takashi Sugino, Hideaki Ninomiya, Junji Shirafuji, and Koichiro Matsuda

Appl. Phys. Lett. 72, 1472 (1998); http://dx.doi.org/10.1063/1.120596 (3 pages) | Cited 5 times

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Phosphidization of GaAs surfaces is attempted with phosphine gas photodecomposed by an ArF excimer laser. Electron traps at and near the phosphidized GaAs surfaces are characterized by isothermal capacitance transient spectroscopy measurements. Phosphidization leads to a reduction in the trap (Ec−0.81 eV) known as an EL2 center and generation of two traps (Ec−0.24 eV and Ec−0.49 eV), which are designated as NL1 and NL2, respectively. A significant metal work-function dependence of the barrier height is demonstrated for Schottky junctions formed on the GaAs surfaces phosphidized under optimum condition, suggesting that phosphidization is effective in reducing surface states of GaAs. © 1998 American Institute of Physics.
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81.05.Ea III-V semiconductors
81.65.Rv Passivation
82.50.Bc Processes caused by infrared radiation
82.50.Hp Processes caused by visible and UV light
61.80.Ba Ultraviolet, visible, and infrared radiation effects (including laser radiation)
73.20.At Surface states, band structure, electron density of states
73.30.+y Surface double layers, Schottky barriers, and work functions
82.30.Lp Decomposition reactions (pyrolysis, dissociation, and fragmentation)

Prebreakdown and breakdown effects in AlGaN/GaN heterostructure field effect transistors

G. Gradinaru, M. Asif Khan, N. C. Kao, T. S. Sudarshan, Q. Chen, and J. Yang

Appl. Phys. Lett. 72, 1475 (1998); http://dx.doi.org/10.1063/1.120597 (3 pages) | Cited 4 times

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Prebreakdown and breakdown effects under high electric fields in AlGaN/GaN heterojunction field effect transistors were studied. In the subthreshold regime, at large drain-to-source voltages (>80 V), along with the gate leakage current, a significant source current was measured. For a wide range of gate-to-source bias voltages in OFF and ON regimes, the breakdown voltage was limited by a rapid buildup of the source current, rather than a process dominated by gate leakage. © 1998 American Institute of Physics.
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85.30.Tv Field effect devices
72.20.Ht High-field and nonlinear effects
77.22.Jp Dielectric breakdown and space-charge effects

Submicron resolution measurement of stress in silicon by near-field Raman spectroscopy

S. Webster, D. N. Batchelder, and D. A. Smith

Appl. Phys. Lett. 72, 1478 (1998); http://dx.doi.org/10.1063/1.120598 (3 pages) | Cited 54 times

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A scanning near-field optical microscope (SNOM) has been constructed that is capable of recording Raman spectra with a spatial resolution of ∼ 150 nm. The SNOM has been used to produce a combined topological and Raman map of a plastically deformed area of a silicon wafer. The variation of the frequency of the 520 cm−1 Raman band with position has been used to estimate the residual stresses associated with the deformation. The measurements demonstrate the feasibility of nondestructive, submicron stress measurement in semiconductors by near-field Raman spectroscopy. © 1998 American Institute of Physics.
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46.80.+j Measurement methods and techniques in continuum mechanics of solids
78.30.Am Elemental semiconductors and insulators
78.20.hb Piezo-optical, elasto-optical, acousto-optical, and photoelastic effects
68.35.Gy Mechanical properties; surface strains
68.35.B- Structure of clean surfaces (and surface reconstruction)
62.20.F- Deformation and plasticity
81.40.Lm Deformation, plasticity, and creep
07.79.Fc Near-field scanning optical microscopes

Valence intersubband lasers with inverted light-hole effective mass

G. Sun, Y. Lu, and J. B. Khurgin

Appl. Phys. Lett. 72, 1481 (1998); http://dx.doi.org/10.1063/1.120610 (3 pages) | Cited 17 times

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We propose a novel intersubband laser based on transition between the ground-state heavy-hole subband (HH1) and light-hole subband (LH1) in a k-space region where the light-hole effective mass is inverted. The laser structure can be electrically pumped with a simple quantum cascade scheme. Our calculation shows that with only a small fraction of the carrier population in the upper subband (LH1), it is possible to achieve population inversion between the two subbands locally in K space where the light-hole effective mass is inverted. Optical gain in excess of 150/cm can be achieved with a pumping current density on the order to 100 A/cm2 at the temperature of liquid nitrogen. © 1998 American Institute of Physics.
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42.60.By Design of specific laser systems
42.55.Px Semiconductor lasers; laser diodes
71.18.+y Fermi surface: calculations and measurements; effective mass, g factor
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