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10 Feb 1997

Volume 70, Issue 6, pp. 677-787

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Localized picosecond resolution with a near-field microwave/scanning-force microscope

D. W. van der Weide

Appl. Phys. Lett. 70, 677 (1997); http://dx.doi.org/10.1063/1.118272 (3 pages) | Cited 20 times

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We modify a scanning-force microscope tip/cantilever with a coaxial metal shield for use as an ultra-small field probe, observing 30 ps waveforms on an integrated circuit at a spatial resolution set by the tip radius, the first direct measurements of electric field at these levels of temporal and spatial resolution. This new ability to acquire topography while maintaining constant tip–sample distance for calibrated measurement or excitation of near-zone picosecond time-resolved electric fields is useful not only for probing advanced circuits but also for localized broadband spectroscopy of condensed matter and biological samples. © 1997 American Institute of Physics.
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07.79.Lh Atomic force microscopes
84.40.Dc Microwave circuits
87.64.Dz Scanning tunneling and atomic force microscopy

Hole-filling of persistent spectral holes in the excitonic absorption band of CuBr quantum dots

J. Valenta, J. Moniatte, P. Gilliot, R. Levy, B. Hönerlage, and A. I. Ekimov

Appl. Phys. Lett. 70, 680 (1997); http://dx.doi.org/10.1063/1.118273 (3 pages) | Cited 5 times

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Persistent spectral-holes (p-SH) are burned in the Z1,2 excitonic band of CuBr nanocrystals by a pulsed laser excitation. The annealing of p-SH is studied by three types of hole-filling (HF) experiments: (i) the spontaneous HF, (ii) thermally-induced HF, and (iii) the laser-induced HF. Results are compared to the well developed theory of the persistent spectral hole-burning (p-SHB) in the system of molecules in amorphous matrices. Both p-SHB and HF phenomena can be explained within the framework of a photochemical reaction like the photoionization of nanocrystals. The potential application of p-SHB to the frequency-domain optical data storage is discussed. © 1997 American Institute of Physics.
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78.66.Jg Amorphous semiconductors; glasses
71.35.Cc Intrinsic properties of excitons; optical absorption spectra
81.07.-b Nanoscale materials and structures: fabrication and characterization
42.79.Vb Optical storage systems, optical disks

Continuous wave ultraviolet frequency upconversion due to triads of Nd3+ ions in fluoroindate glass

L. de S. Menezes, Cid B. de Araújo, G. S. Maciel, Y. Messaddeq, and M. A. Aegerter

Appl. Phys. Lett. 70, 683 (1997); http://dx.doi.org/10.1063/1.118274 (3 pages) | Cited 21 times

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We have observed ultraviolet upconversion fluorescence from the 4D3/2 and 2P3/2 levels of Nd3+ in fluoroindate glass under infrared pumping. It was found that the excitation of a large population in the 4F3/2 metastable level allows to achieve strong upconversion emissions at 354 and 382 nm. A simple rate equation model reproduces the temporal behavior of the upconverted emission and allows us to estimate the energy transfer rate among three Nd3+ ions participating in the process. © 1997 American Institute of Physics.
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42.65.Ky Frequency conversion; harmonic generation, including higher-order harmonic generation
42.70.Hj Laser materials
78.55.Hx Other solid inorganic materials

Photoluminescence of LiTaO3:Pr

W. Ryba-Romanowski, I. Sokólska, S. Gołab, and T. Łukasiewicz

Appl. Phys. Lett. 70, 686 (1997); http://dx.doi.org/10.1063/1.118899 (2 pages) | Cited 6 times

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Single crystals of LiTaO3 doped with praseodymium were grown by the Czochralski method from congruent melt and their optical properties were examined. It has been found that the Pr3+ ions in LiTaO3 occupy several nonequivalent sites differing in the crystal field strength. In addition, the structural disorder associated with Li deficiency gives rise to strong inhomogeneous broadening of both the optical absorption and emission lines. In contrast to isostructural LiNbO3:Pr, the relaxation of the excited 3P0 level of praseodymium is governed by radiative transitions, which terminate on excited multiplets and make the LiTaO3:Pr3+ crystals promising for four-level lasing in the visible range. © 1997 American Institute of Physics.
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78.55.Hx Other solid inorganic materials
42.70.Mp Nonlinear optical crystals

Beam divergence and waist measurements of laser diodes by near-field scanning optical microscopy

W. D. Herzog, M. S. Ünlü, B. B. Goldberg, G. H. Rhodes, and C. Harder

Appl. Phys. Lett. 70, 688 (1997); http://dx.doi.org/10.1063/1.118258 (3 pages) | Cited 22 times

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We demonstrate the use of near-field scanning optical microscopy (NSOM) for the measurement of the beam properties of single quantum well, graded index separate confinement heterojunction ridge laser diodes. Using NSOM, we measure the field intensity in the transverse plane at near field and as a function of distance from the facet. The divergence of the laser beam and the beam waists in vertical and lateral dimensions are directly measured and the astigmatism of the mode is determined. In the near field, we observe a nearly ideal Gaussian shape in the vertical dimension which is consistent with the beam divergence as measured in the far field. In the lateral dimension, the beam shape deviates from the ideal Gaussian since the mesa structure of the laser diode provides an effective step-index waveguide. The non-Gaussian structure of the mode is also observed in the beam divergence properties. © 1997 American Institute of Physics.
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42.55.Px Semiconductor lasers; laser diodes
42.60.Jf Beam characteristics: profile, intensity, and power; spatial pattern formation
07.79.Fc Near-field scanning optical microscopes

Monolithic p-i-n GaAlAs multiple quantum well photorefractive device

Parviz Tayebati, Christos Hantzis, and R. N. Sacks

Appl. Phys. Lett. 70, 691 (1997); http://dx.doi.org/10.1063/1.118241 (3 pages) | Cited 6 times

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In this letter, we report a monolithic p-i-n multiple quantum-well (MQW) GaAlAs photorefractive device operating in reflection mode. The device structure consists of a photorefractive structure grown with low temperature grown GaAlAs charge blocking layers on top of a 20 period n-type GaAlAs/AlAs quarter wave stack mirror. The device operates by double passing mutually coherent beams through the photorefractive structure exhibiting nearly 0.23% input diffraction efficiency. Because of fast sweep time in ultranarrow-barrier MQWs used here, the writing energy density of approximately 20 nJ/cm2 is a nearly seven (7) improvement over previously reported devices using 100 Å GaAlAs barriers. © 1997 American Institute of Physics.
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42.79.Hp Optical processors, correlators, and modulators
85.60.Bt Optoelectronic device characterization, design, and modeling
42.65.Jx Beam trapping, self-focusing and defocusing; self-phase modulation

High-power (>0.9 W cw) diffraction-limited semiconductor laser based on a fiber Bragg grating external cavity

Donald M. Cornwell and Heather J. Thomas

Appl. Phys. Lett. 70, 694 (1997); http://dx.doi.org/10.1063/1.119263 (2 pages) | Cited 5 times

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We have developed a high-power (>0.9 W cw) diffraction-limited semiconductor laser based on a tapered semiconductor optical amplifier using a fiber Bragg grating in an external cavity configuration. Frequency-selective feedback from the fiber grating is injected into the amplifier via direct butt coupling through a single mode fiber, resulting in a spectrally stable and narrow (<0.3 nm) high-power laser for solid-state laser pumping, laser remote sensing, and optical communications. © 1997 American Institute of Physics.
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42.55.Px Semiconductor lasers; laser diodes
42.79.Dj Gratings
42.60.Pk Continuous operation

Analysis of laser absorption on a rough metal surface

L. K. Ang, Y. Y. Lau, R. M. Gilgenbach, and H. L. Spindler

Appl. Phys. Lett. 70, 696 (1997); http://dx.doi.org/10.1063/1.118242 (3 pages) | Cited 13 times

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We have developed a simple model to estimate the cumulative absorption coefficient of an ultraviolet laser pulse impinging on a pure metal, including the effects of surface roughness whose scale is much larger than the laser wavelength λ. The multiple reflections from the rough surface may increase the absorption coefficient over a pristine, flat surface by an order of magnitude. Thus, as much as 16% (at room temperature) of the power of a 248 nm KrF excimer laser pulse may be absorbed by an aluminum target. A comparison with experimental data is given. © 1997 American Institute of Physics.
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79.20.Ds Laser-beam impact phenomena
61.80.Ba Ultraviolet, visible, and infrared radiation effects (including laser radiation)
81.05.Bx Metals, semimetals, and alloys

A novel yellow-emitting material, 5,5′′-bis{4-[bis(4-methylphenyl)amino] phenyl}-2,2′:5′,2′′-terthiophene, for organic electroluminescent devices

Tetsuya Noda, Hiromitsu Ogawa, Naoki Noma, and Yasuhiko Shirota

Appl. Phys. Lett. 70, 699 (1997); http://dx.doi.org/10.1063/1.118243 (3 pages) | Cited 24 times

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A novel amorphous molecular material, 5,5′′-bis{4-[bis(4-methylphenyl)amino]phenyl}2,2′:5′,2′′-terthiophene (BMA-3T), has been found to function as a yellow-emitting material in organic electroluminescent (EL) devices. Both the single layer EL device using BMA-3T alone and the double layer EL device consisting of an emitting layer of BMA-3T and an electron-transport layer of tris(8-quinolinolato)aluminum sandwiched between indium-tin-oxide (ITO) and an alloy of magnesium and silver (∼10:1) electrodes emitted a bright yellow light resulting from BMA-3T. The double layer EL device showed much better performances than the single layer EL device, exhibiting a maximum luminance of ∼13 000 cd m−2 at a driving voltage of 18 V, and a luminous efficiency of 1.1 lm W−1 at a luminance of 300 cd m−2. © 1997 American Institute of Physics.  
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85.60.Jb Light-emitting devices
85.65.+h Molecular electronic devices
78.60.Fi Electroluminescence
42.70.Jk Polymers and organics

Second harmonic generation in a photonic crystal

Jordi Martorell, R. Vilaseca, and R. Corbalán

Appl. Phys. Lett. 70, 702 (1997); http://dx.doi.org/10.1063/1.118244 (3 pages) | Cited 78 times

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Phase matched second harmonic generation is observed experimentally in a centrosymmetric crystalline lattice of dielectric spheres of optical dimensions. The inversion symmetry is broken locally at the surface of each sphere in such a way that the scattered second harmonic light interferes constructively leading to a nonvanishing macroscopic field. Phase matching of the fundamental and second harmonic waves in such periodic lattice is observed to be naturally provided by the bending of the photon dispersion curve at the edge of the Bragg reflection band of a given set of lattice planes. © 1997 American Institute of Physics.
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42.65.Ky Frequency conversion; harmonic generation, including higher-order harmonic generation
42.70.Qs Photonic bandgap materials
78.66.Vs Fine-particle systems

Controlling and tuning strong optical field gradients at a local probe microscope tip apex

Olivier J. F. Martin and Christian Girard

Appl. Phys. Lett. 70, 705 (1997); http://dx.doi.org/10.1063/1.118245 (3 pages) | Cited 87 times

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We show that strong optical field gradients can be created at the tip apex of a local probe microscope illuminated by an external light source. We demonstrate that these confined fields can be easily, precisely and continuously tuned by changing the polarization and the incidence of the external field. We also investigate the topology of the field intensity in the tip–surface junction. © 1997 American Institute of Physics.
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07.79.Fc Near-field scanning optical microscopes
42.25.-p Wave optics
42.30.-d Imaging and optical processing

Nonlinear optical properties of silicon nanoclusters

S. Vijayalakshmi, M. A. George, and H. Grebel

Appl. Phys. Lett. 70, 708 (1997); http://dx.doi.org/10.1063/1.118246 (3 pages) | Cited 34 times

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The nonlinear and linear optical responses of Si nanoclusters at λ = 355 nm were measured. The nanoclusters were laser ablated on quartz substrates. χ(3) values as high as 2.28×10−5 esu (as measured by the Z-scan technique) and lifetime as long as 143 ns were measured for clusters of an average size of 11 nm. The optical properties were strongly correlated with the clusters’ sizes. © 1997 American Institute of Physics.
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42.70.Nq Other nonlinear optical materials; photorefractive and semiconductor materials
42.65.An Optical susceptibility, hyperpolarizability
61.46.-w Structure of nanoscale materials
78.66.Sq Composite materials

Oxidation kinetics of TiN layers: Exposed and beneath Pt thin films

Paul C. McIntyre, Scott R. Summerfelt, and Carl J. Maggiore

Appl. Phys. Lett. 70, 711 (1997); http://dx.doi.org/10.1063/1.118247 (3 pages) | Cited 18 times

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Oxidation kinetics are reported for thin films of TiN, both directly exposed to a dry oxygen ambient and beneath polycrystalline Pt films of ∼100 nm thickness. Oxygen resonance backscattering spectrometry was used to detect thin oxide layers at the Pt/TiN interface produced by oxidation annealing at 550–650 °C. A linear oxidation rate law was observed for the buried TiN film, indicating the oxidation rate is independent of average titanium oxide thickness. The linear rate constant had an activation enthalpy of 2.4±0.1 eV. © 1997 American Institute of Physics.
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66.30.Ny Chemical interdiffusion; diffusion barriers
68.60.Dv Thermal stability; thermal effects
81.65.Mq Oxidation
82.65.+r Surface and interface chemistry; heterogeneous catalysis at surfaces

Time-frequency characterization of magnetostatic envelope soliton waves

D. Dragoman and M. Dragoman

Appl. Phys. Lett. 70, 714 (1997); http://dx.doi.org/10.1063/1.118248 (3 pages)

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The time-frequency characterization is used to test if measured waveforms are magnetostatic solitons. Measured bright and dark magnetostatic solitons are analyzed in the time-frequency domain using the Wigner transform. © 1997 American Institute of Physics.
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41.20.Jb Electromagnetic wave propagation; radiowave propagation
75.70.Ak Magnetic properties of monolayers and thin films

Electron beam induced crystallization in Fe-doped SnO2 nanoparticles

Bin Lu, Changsui Wang, and Yuheng Zhang

Appl. Phys. Lett. 70, 717 (1997); http://dx.doi.org/10.1063/1.118263 (3 pages) | Cited 24 times

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Nanoscale particles of Fe-doped SnO2 were intensively radiated in a high-energy electron beam observed in situ in a transmission electron microscope. Generation of small crystalline grains from agglomerated nanoparticles was observed. Electron diffraction patterns confirmed that the grains belonged to the orthorhombic phase of SnO2, which forms only under pressures higher than 140 kbar according to previous research. A possible process for the phase transition is discussed. The result suggests a novel method of producing orthorhombic SnO2 at low pressure. © 1997 American Institute of Physics.
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61.46.-w Structure of nanoscale materials
68.37.Hk Scanning electron microscopy (SEM) (including EBIC)
68.37.Lp Transmission electron microscopy (TEM)
64.70.K- Solid-solid transitions

Dual frequency cholesteric light shutters

Ming Xu and Deng-Ke Yang

Appl. Phys. Lett. 70, 720 (1997); http://dx.doi.org/10.1063/1.118261 (3 pages) | Cited 15 times

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We developed a dual frequency cholesteric light shutter which utilizes a cholesteric liquid crystal; the dielectric anisotropy of the material changes from positive to negative when the frequency of applied voltage is increased. The shutters are switched to the transparent homeotropic texture by low frequency voltages, and switched to the reflecting planar texture by high frequency voltages. We designed a waveform which reduced the transition time from the homeotropic texture to the planar texture to less than 100 ms. © 1997 American Institute of Physics.
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42.79.Hp Optical processors, correlators, and modulators
61.30.-v Liquid crystals
78.20.Jq Electro-optical effects

Raman study of the relationship between nanoparticles and photoluminescence in spark-processed silicon

S. Rupp, J. Quilty, H. J. Trodahl, M. H. Ludwig, and R. E. Hummel

Appl. Phys. Lett. 70, 723 (1997); http://dx.doi.org/10.1063/1.118249 (3 pages) | Cited 11 times

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Spark-processed silicon (sp-Si) that strongly photoluminesces (PL) in the blue and green regions of the visible spectrum has been analyzed by Raman scattering, in order to probe a possible relationship between the presence and size of Si nanoparticles and PL emission wavelengths. Spatially resolved Raman spectra were measured across spark-processed regions, scanning areas which vary in PL intensity but not wavelength. The observed small shifts and broadenings of the Raman signals indicate the presence of Si particles having diameters of about 15 nm in the central, photoluminescing section of the sp region. Slightly smaller Si crystallites with sizes of about 8–9 nm were found in the halo region which does not contribute to PL. Furthermore, the Raman peak shifts and broadenings are essentially identical for blue and green photoluminescing sp-Si. These results suggest that the PL of sp-Si is not caused by a quantum-size effect which is coupled to the presence of Si nanoparticles. © 1997 American Institute of Physics.
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78.55.Ap Elemental semiconductors
78.30.Am Elemental semiconductors and insulators
78.66.Jg Amorphous semiconductors; glasses

Specific volumes of the Zr41.2Ti13.8Cu12.5Ni10.0Be22.5 alloy in the liquid, glass, and crystalline states

K. Ohsaka, S. K. Chung, W. K. Rhim, A. Peker, D. Scruggs, and W. L. Johnson

Appl. Phys. Lett. 70, 726 (1997); http://dx.doi.org/10.1063/1.118250 (3 pages) | Cited 56 times

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The specific volumes of the Zr41.2Ti13.8Cu12.5Ni10.0Be22.5 alloy as a function of temperature, T, are determined by employing an image digitizing technique and numerical calculation methods applied to the electrostatically levitated spherical alloy. The linear fitting of the volumes of the alloy in the liquid, Vl, glass, Vg, and crystalline Vc, states in the temperature ranges shown in parentheses are Vl(T) = 0.1583+8.877×10−6T(cm3/g) (700–1300 K);Vg(T) = 0.1603+5.528×10−6T (400–550 K);Vc(T) = 0.1583+6.211×10−6T(400–850 K). The average volume thermal expansion coefficients within the temperature ranges are determined to be 5.32, 3.39, and 3.83×10−5 (1/K) for the liquid, glass, and crystalline states, respectively. © 1997 American Institute of Physics.
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65.20.-w Thermal properties of liquids
65.40.gd Entropy
64.70.P- Glass transitions of specific systems
64.70.Q- Theory and modeling of the glass transition
65.40.De Thermal expansion; thermomechanical effects

On the single domain nature of stoichiometric LiNbO3 grown from melts containing K2O

V. Bermúdez, P. S. Dutta, M. D. Serrano, and E. Diéguez

Appl. Phys. Lett. 70, 729 (1997); http://dx.doi.org/10.1063/1.119265 (3 pages) | Cited 10 times

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Stoichiometric crystals of LiNbO3 were grown by the Czochralski technique from a congruent melt with 6 wt% of K2O flux dopant. The crystals were always single domain irrespective of the seed history. Analysis of the domain structure at the seed-crystal boundary reveals a domain inversion in certain cases. During crystal growth, self-poling of initially unpoled congruent LiNbO3 seeds was observed. It is thought that the monodomain nature of the crystals is attributed to the reduction of native defects due to their stoichiometric Li-Nb composition. © 1997 American Institute of Physics.
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77.80.Dj Domain structure; hysteresis
61.66.Bi Elemental solids
61.66.Dk Alloys
42.70.Mp Nonlinear optical crystals
81.10.Fq Growth from melts; zone melting and refining

Overpressurized bubbles versus voids formed in helium implanted and annealed silicon

P. F. P. Fichtner, J. R. Kaschny, R. A. Yankov, A. Mücklich, U. Kreißig, and W. Skorupa

Appl. Phys. Lett. 70, 732 (1997); http://dx.doi.org/10.1063/1.118251 (3 pages) | Cited 34 times

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The formation of helium induced cavities in silicon is studied as a function of implant energy (10 and 40 keV) and dose (1×1015, 1×1016, and 5×1016 cm−2). Specimens are analyzed after annealing (800 °C, 10 min) by transmission electron microscopy (TEM) and elastic recoil detection (ERD). Cavity nucleation and growth phenomena are discussed in terms of three different regimes depending on the implanted He content. For the low (1×1015 cm−2) and high (5×1016 cm−2) doses our results are consistent with the information in the literature. However, at the medium dose (1×1016 cm−2), contrary to the gas release calculations which predict the formation of empty cavities, ERD analysis shows that a measurable fraction of the implanted He is still present in the annealed samples. In this case TEM analyses reveal that the cavities are surrounded by a strong strain field contrast and dislocation loops are generated. The results obtained are discussed on the basis of an alternative nucleation and growth behavior that allows the formation of bubbles in an overpressurized state irrespective of the competition with the gas release process. © 1997 American Institute of Physics.
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61.72.Qq Microscopic defects (voids, inclusions, etc.)
61.72.Cc Kinetics of defect formation and annealing
61.72.uf Ge and Si

Electrical properties of high resistivity 6H–SiC under high temperature/high field stress

G. Gradinaru, T. S. Sudarshan, S. A. Gradinaru, W. Mitchell, and H. M. Hobgood

Appl. Phys. Lett. 70, 735 (1997); http://dx.doi.org/10.1063/1.118264 (3 pages) | Cited 2 times

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The influence of ambient temperature and applied electric field on the electrical properties of high resistivity (1–30 kΩ cm), semi-insulating (>100 kΩ cm), and insulating (1011–1012 Ω cm) single-crystal 6H–SiC is reported. Current–voltage (I–V) characteristics of lateral metal-semiconductor-metal test structures were measured in vacuum in a temperature range of 295–730 K and under moderate pulsed electric fields (0.5–80 kV/cm). It is shown that the resistivity of the undoped 6H–SiC varies strongly with the ambient temperature after a temperature/field function dominated by a factor containing the activation (ionization) energy of residual boron of 0.35 eV. The dominant activation energy of semi-insulating Vanadium-compensated material (6H–SiC:V) varies with the ambient temperature, increasing from ∼0 eV at 295–320 K to ∼0.8 eV at T⩾600 K. This result can explain the relatively low decrease of the resistivity of insulating 6H–SiC at very high ambient temperatures and its viability as a substrate for next-generation high temperature microwave integrated circuits based on large band gap semiconductors. © 1997 American Institute of Physics.
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72.20.Fr Low-field transport and mobility; piezoresistance
72.80.Sk Insulators
72.80.Jc Other crystalline inorganic semiconductors
73.40.Sx Metal-semiconductor-metal structures

Acceptor assessment and the role of carbon in semi-insulating GaAs

W. J. Moore and R. L. Henry

Appl. Phys. Lett. 70, 738 (1997); http://dx.doi.org/10.1063/1.118265 (3 pages)

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A method for identifying and quantifying acceptor contamination in semi-insulating (SI) GaAs is described. The method has been applied to commercial SI GaAs and to NRL zone-refined ingots. Results indicate that carbon is not the only acceptor present in significant concentrations in typical SI GaAs. Zinc is present in essentially all samples and is the dominant shallow acceptor in a significant fraction of the commercial material studied. The method consists of moving the Fermi level to the ground state of the shallowest acceptor present, usually carbon, by diffusing copper into the material. An infrared transmission measurement identifies the neutral acceptors from their electronic 1s-2p intrasite excitation. The strength of the absorption is proportional to the neutral acceptor concentration. Sensitivities are greatest for shallow acceptors where neutral acceptor concentrations as low as 5×1012 cm−3 can be identified and quantified. © 1997 American Institute of Physics.
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71.55.Eq III-V semiconductors
66.30.J- Diffusion of impurities
78.30.Fs III-V and II-VI semiconductors
81.05.Ea III-V semiconductors

Very small oxide-confined vertical-cavity surface-emitting lasers with a bulk active region

H. Deng, Q. Deng, and D. G. Deppe

Appl. Phys. Lett. 70, 741 (1997); http://dx.doi.org/10.1063/1.118266 (3 pages) | Cited 6 times

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Data are presented characterizing very small oxide aperture vertical-cavity surface-emitting lasers with a 0.5-μm-thick bulk GaAs active region. The transverse far field is independent of the aperture size for diameters ⩽3 μm, although threshold reduction occurs with reducing aperture size down to ∼0.5 μm diam. Threshold reduction is attributed to improved overlap between the optical mode and gain profile. The large signal temporal response is characterized using optical gain switching. © 1997 American Institute of Physics.
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42.60.Da Resonators, cavities, amplifiers, arrays, and rings
42.55.Sa Microcavity and microdisk lasers
78.66.Fd III-V semiconductors

Grain interaction effect in electronic properties of silicon nanosize films

A. B. Filonov, A. N. Kholod, V. A. Novikov, V. E. Borisenko, L. Vervoort, F. Bassani, A. Saul, and F. Arnaud d’Avitaya

Appl. Phys. Lett. 70, 744 (1997); http://dx.doi.org/10.1063/1.118267 (3 pages) | Cited 13 times

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Electronic properties of both nanometer thickness (111) monocrystalline and nanocrystalline free standing silicon films were calculated within a self-consistent linear combination of atomic orbitals method. Grained nature of the nanocrystalline films is found to induce both a direct band gap and its reduction (down to about 2 eV) with respect to an isolated grain of same size. © 1997 American Institute of Physics.
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71.20.Mq Elemental semiconductors
71.15.Ap Basis sets (LCAO, plane-wave, APW, etc.) and related methodology (scattering methods, ASA, linearized methods, etc.)
73.22.-f Electronic structure of nanoscale materials and related systems
73.21.-b Electron states and collective excitations in multilayers, quantum wells, mesoscopic, and nanoscale systems

Passivation of GaAs/AlGaAs heterojunction bipolar transistors by S2Cl2 solution

Xian-an Cao, Xiao-yuan Hou, Xi-ying Chen, Zhe-shen Li, Run-zhou Su, Xun-min Ding, and Xun Wang

Appl. Phys. Lett. 70, 747 (1997); http://dx.doi.org/10.1063/1.118268 (3 pages) | Cited 12 times

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The diluted S2Cl2 solution has been employed to treat the GaAs/AlGaAs heterojunction bipolar transistors. It is shown that the dc characteristics of the transistor could be improved significantly and the passivation effect is not subject to degradation by heating to 150 °C in atmospheric air and immersing in water. A real-time monitoring technique is proposed which provides good control of the passivation stopping point. © 1997 American Institute of Physics.
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85.30.Pq Bipolar transistors
81.65.Rv Passivation
73.40.Kp III-V semiconductor-to-semiconductor contacts, p-n junctions, and heterojunctions
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